US3578404A

US3578404A - Automatic reaction rate apparatus

Info

Publication number: US3578404A
Application number: US687707A
Authority: US
Inventors: Wilhelm E Walles; William F Tousignant
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1967-12-04
Filing date: 1967-12-04
Publication date: 1971-05-11
Anticipated expiration: 1988-05-11
Also published as: FR1603481A; SE357063B; BE724830A; DE1811500A1; CH512738A; GB1251678A; NL6817360A

Abstract

METHOD AND APPARATUS FOR ASCERTAINING THE RATE OF REACTION THAT EVOLVES OR CONSUMES A GAS; COMPRISING A CLOSED, CIRCUITOUS DUCT A FIRST UPSTREAM END OF WHICH ORIGINATES AT A DOWNSTREAM PORTION OF A REACTION VESSEL, PROCEEDS THROUGH VALVE MEANS, PUMP MEANS, AND PRESSURE SENSING MEANS, MEANS FOR SENSING AT LEAST ONE KIND OF INFLUENCE UPON THE RATE OF A REACTION IN SAID REACTION VESSEL, AND OPTIONALLY OTHER MEANS, RETURNING TO TERMINATE AT A SECOND, DOWNSTREAM END AT AN UPSTREAM PORTION OF SAID REACTION VESSEL WHICH, IN TURN, COMMUNICATES WITH SAID FIRST END. BY CONTROL UNDER PROVIDED TIMING MEANS, CONFINED GAS PRESSURE IS SENSED IN INCREMENTS, ALONG WITH INCREMENTS OF REACTION-RATE INFLUENCES SUCH AS HEAT; DURING OPERATION THE INTERIOR OF THE DUCT AND VESSEL ARE RETURNED TO REFERENCE PRESSURE AFTER EACH SENSING INCREMENT AND ARE SUBJECT TO SUBSTANTIALLY CONTINUOUS MOVEMENT OF GAS.

Description

May 11, 1971 w. E. wALLEs ET AL AUTOMATIC REACTION RATE APPARATUS' 4 Sheets-Sheet 1 Filed Dec'. 4 .v 1967 1M Q M u\m 1 8 5 0 z we 9/.1I w V lll m1 ufl M 11 lrllll maJ F/n INVENTORS. 19t 5 #1 /m4?? wq//es l 0m OLIS! nan f W AGENT May ll, 1971 w, E, WALLES ETAL 3,578,404

AUTOMATIC REACTION RATE APPARATUS 4 Sheets--Sheet 2 Filed Dec. 4. 1967 1r s efm.) d M 2% W j@ se eys ma. wedmm .m 5 f; x i i w @man /cx wur mexbm efr fs P /3 Jee md@ /na @Jm ,mmillj Cn Prn om ww, f! |l||f|||tl||l| 6/||||| Q11: la F//Gh7 E fw n) r@ /0 am elo /U 6 ke :mdr n .mm Mr @fr f l om he @u r c 1. arf i n r, i 152. f D ,.pe /Gf /0 C fr@ 6 f d wQ/ m we ne lr f A@ /vmbm w r e .Ore C Hemd@ n Q00 Prh .mno/r mebe r .0H lr lrro, he/rem/ /ahs/reu /n 5m @bw c/rOn/r/ /0a/menr5 cfr .re r/ Si gi @M i e@ r 0 0l mh wmmmlwpp ma@ H 5. l I l I I l l l l l I|I| .I I. Tf.n In U /s llllllllllllll IIL M my ye 7' fm e Sca le and 0x15 Ff/lg. 2

4 Sheets-,Sheet 5 May 1l 1971 w. E. wALLEs ETAL v AUTOMATIC REACTION RATE APPARATUS Filed Dec. 4|. 1967 Dafa f/ems fo be emp /oged w. E. wALLEs ET AL AUTOMATIC REACTION' RATE APPARATUS May 11, 11971 Filed Dec. 4. 1967 Gas Source im QMS www ma@ r 1.31m mfr M .,.OVH

w By Wai Patented May 11, 1971 U.S. Cl. 23-230 Z5 Claims ABSTRACT OF THE DISCLOSURE Method and apparatus for ascertaining the rate of reaction that evolves or consumes a gas; comprising a closed, circuitous duct a iirst upstream end of which originates at a downstream portion of a reaction vessel, proceeds through valve means, pump means, and pressure sensing means, means for sensing at least one kind of inuence upon the rate of a reaction in said reaction vessel, and optionally other means, returning to terminate at a second, downstream end at an upstream portion of said reaction vessel which, in turn, communicates with said first end. By control under provided timing means, conlined gas pressure is sensed in increments, along with increments of reaction-rate influences such as heat; during operation the interior of the duct and vessel are returned to reference pressure after each sensing increment and are subject to substantially continuous movement of gas.

BACKGROUND OF THE INVENTION Field of the invention lIn 1662, Sir Robert Boyle (1627-1691) made the careful study of pressure-temperature-volume relationships in gases that laid the basis for modern gas studies, and made possible the refinements contributed in 1873 by Van der Waals.

In 1808, Gay-Lussac enunciated the principle that gases combine in fixed volume ratios to produce compounds of ixed compositions.

In 1811, Amadeo Avogadro (1776-1856) enunciated the hypothesis that equal volumes of gases under the same conditions of temperature and pressure contain the same numbers of molecules. This, together with the later work of Cannizzaro led to improved studies of molecular mass.

Due allowance being made for pressure and temperature, the close relationship between gas volume and reaction stoichiometry has been closely studied and widely used.

Prior art Automatic, uniform, averaged sampling of gases is described at 32 Journal of the Society of the Chemical Industry 1093 (1913) by Gray, and 48 same Journal 242 (1929).

To provide mechanical compensation for temperaturepressure fluctuations, Lunge (23 Berichte 440, 1890) devised and (25 Ber. 3157, 1892) modified his gas volumeter. Various other means of doing essentially the same thing have been devised. Pettersson described (25 Zeitschrift der analytischen Chemie 407) his compensator in 1886. Modifications and improvements of these devices are almost too numerous to list and are notorious.

A version of the rotameter rate-of-ilow meter is described (l Der chemische `Fabrik 32) by Hardebech in 1928.

lGas analyses of classic precision were carried out by Cavendish and by Bunsen with very simple equipment. The Winkler absorption burette of 1872 is useful now nearly a century later.

Louis Hengist Orsat, engineer, 19 lRue de la Victoire, Paris, applied for his British Patent (application 1853) on May 22, 1873, covering the Orsat burette which, in innumerable forms, is widely used yet in wet chemical analysis of Igases, see Chemical News Apr. 17, 1874, page 177.

Vinegar and pear or potash had been used since -at least 1700 to provide very rough mutual analyses of their respective goodness: the weight of refined ash or volume of vinegar to bring an end to effervescence was noted.

In 1883, Kjeldahl published his method of nitrogen analysis which assumed conversion of all nitrogen to ammonium sulfate, its release by sodium hydroxide, and quantitative uptake by sulfuric acid.

Joseph Barcroft, in 1902 applied the manometric measurement of gas pressure to enzyme studies.

Otto Warburg (142 Biochemische Zeitschrift 317 and especially 324 and following) in 1923 described the manometric apparatus which is in current use and is known by his name. It is believed by the present inventors to be the nearest approach of the prior art to the present invention.

Meantime, automated means that are usually electrical means for utilization of some simple property of a dluid have become known. Thermal conductivity of gases; electrical, e.g., ionic, conductivity of uids, weight of volume of a iluid, and the like, are utilized. Occasionally such automated sensing of a simple property is used reflexly to control a chemical function. Representative of such developments are U.S. Pats. 2,835,715, 3,018,654 and 3,018,655.

DESCRIPTION OF THE PRESENTI' INVENTION The present invention is concerned with a method of quantitative chemical detection and analysis and with 'automatic mechanical instrumentation in the eld of chemical reactions, and is particularly directed to a novel machine and method for determining and employing certain quantitative rate data of a chemical reaction.

One of the more important characteristics of a chemical reaction, hitherto very diicult to determine, is the rate of reaction, which may be considered as the molar rate of reaction per mole of limiting reactant per unit time. Because of the ease and speed with which the present machine ascertains the data necessary to evaluate the rate of even lvery slow chemical reactions, it is informally and for convenience called an Automatic Reaction Rate Apparatus, which is here abbreviated to ARRA; although because its operation can also readily be only semi-automatic, and further because it has been used repeatedly in the determination of many matters other than rate of reaction, the name is in no way limiting.

'Ihe method of the present invention will be more easily understood after a primitive embodiment of the machine has been described.

THE PROT OTYPE MACHINE The general concept of the present machine is set forth in very simple form in the embodiment of the diagrammatic drawing in FIG. 1 to which reference is had, following. This embodiment has generally been incapable of the speed and accuracy deemed to be necessary, but by its simplicity it illustrates the principle involved, without the complications of certain critical and distinguishing improvements that are set forth hereinafter.

Reaction of which a characteristic is to be studied, essentially and critically a reaction which directly or indirectly evolves or consumes gas, is reaction of a sample here shown as sample 20. The reaction of this sample takes place within part of a closed interior circuit cavity of the machine, and the part indicated in FIG. 1 as sample receiving means 10, here an enlarged portion of the machine, communicates with further interior portions of the machine circuit cavity by means of tubing.

Valve means 60, here shown to comprise two 2-way valves, is adapted to close the said interior cavity gas tight, or, when desired, valve means 60 operates to pass gas via gas inlet 5 through the interior of the said machine including through sample 20 and outlet 65.

The present machine provides also stirring means 45. These serve to maintain a minimum dimension-temperature gradient within sample 20. Calibration means 120 is also provided and consists essentially of means whereby to effect a change of controlled magnitude in the interior volume of the machine; here, and in the embodiment that is the best presently known to the inventors, this is constructed of an index-bearing plunger cooperating with a calibrated barrel, that have close fitting, mating adjacent surfaces, so that the plunger fits within the barrel, in a fluidtight but slidable manner.

The embodiment schematically represented in FIG. l implies the premise that the predominant controllable influence upon the reaction to be studied is the temperature of the reaction mixture. Hence this embodiment comprises reaction temperature sensing means 30. Any operable means may be employed. A preferred form is a standard laboratory thermocouple. Heating means 155 is provided and is under control of at least reaction temperature sensing means 30 and also, optionally, timing means 70, whereby the temperature of sample 20 is maintained at a predetermined value for a predetermined period of time, and, if desired, automatically brought to a different value thereafter, by operation conjointly of heating means 155 and timing means 70.

The progress of the reaction of sample 20 within the machine with valve means 60 closed brings about a change in gas pressure. This is sensed in a quantified way by gas pressure sensing mean 90, here an electromechanical transducer in which a change in gas pressure causes a displacement of. a diaphragm upon which is imposed the gas pressure to be sensed, the displacement being coupled to, for example, a strain gauge or a piezoelectric element or one electrode of a variable capacitor, giving rise to a quantified change in an electric current output of which the quantitative value is a function of and indicates gas pressure. In order to be useful for further study, the outputs of the present embodiments of reaction temperature sensing means 30 and gas pressure sensing means 90 require further processing, such as translation into a symbolic form.

In the present embodiment, the quantified electrical output is conductively connected with intelligence processing means 140, presently a mechanical recording device in which, with respect to a calibration-bearing paper that 'is moved according to a predetermined time base, the

position of a marking pen is controlled by the quantitative value of the said electrical output. Thereby, the present machine produces directly a graph which can be studied and interpreted in numerous ways.

The time-controlled operation of various parts of the present machine, which is essential to the automatic and most useful employment of the machine, is under control 'of timing means 70, which has typically been a synchronous electric motor driving a shaft that bears cams, the shaft revolving at a predetermined speed, typically 0.1 to 1.0 revolution per minute, the cams being juxtaposed operably adjacent cam-controlled electric switches, the relative circumferential cam positions controlling the relative function timing, the said switches providing electrical control of said time controlled parts. The indicated shaft speed provides for one entire cyclic operation, and repli- `cations at the same rate. A ten minute cycle has been satisfactory.

While practicable embodiments of the present machine comprise numerous necessary refinements and modifications not indicated in diagrammatic drawing FIG. l, the elemental operation of the machine and the method of the present invention are readily understood by reference to the cooperative interaction of the means there indicated. It is to be assumed that any and all portions, and particularly any interior circuit cavity of the said machine, may readily be mechanically detached from and reattached to other adjacent, contacting, or abutting portions of the said machine by the provision, wherever desired, of gastight joints, not usually shown herein, within, or between and connecting, the various elements of which the said apparatus is composed.

Sample 20 is introduced, and in a laboratory this is usually but not critically done by a human operator, and positioned within sample receiving means 10. The assembly of the machine brings gas introducing means 25 into a position whereby gas from an exterior gas source 50 via gas inlet 5 is readily introduced into and throughout sample 20.

All parts of the said machine being assembled together gas tight after introduction of sample 20, gas through inlet 5 and valve means 60 is caused to pass through gas pressure sensing means and further to the upstream indicated gas introducing means 25 (here a glass tube) and thence through sample 20: from sample receiving means 10, gas then flows downstream to valve means 60 and outlet 65. This condition is caused to be maintained by the operation of valve means 60, for such time as may be necessary to flush from the sample and from the interior of the machine any gas other than that introduced from gas source, and, thereupon, to achieve an equilibrium gassaturated condition throughout the interior of the said machine including sample 20.

It is assumed that, as the machine is operated, sample 20 is maintained under conditions, for example, heat, under which a reaction of sample 20 takes place or is expected to take place with the direct or indirect evolution or consumption of gas. The actual choice of temperatures will depend upon the nature of the sample and other factors, and will be known to or easily determined by skilled chemists, biologists and the like.

Gas flow via gas inlet 5 through the machine and to outlet 65 is continued until the machine achieves a satisfactory initial gas flush and saturation at a norm or reference pressure, which can be atmospheric pressure. By the inlet admission of gas under exalted pressure, and its release to waste under a pressure retaining valve (not shown), superatmospheric pressures are readily employed. Also, subatmospheric pressures can be used. Valve means 60 is then operated to close the interior of the said machine so as to confine gaseous contents, and permit their circuitous flow within it. Gas inlet 5 may be simply closed by a valve or, preferably, gas from gas inlet 5 is diverted by appropriate operation of valve means 60 to outlet `65, the rate of flow remaining unaltered. This preferable diversion wastes only small amounts of gas, but obviates recurring adjustment of rate of gas flow and increases accuracy: but is not critical. In the resulting situation, with the interior cavity of the machine saturated with gas at reference pressure and closed to gas ingress or egress, the state of the reaction to be studied is permitted to achieve substantial equilibrium and a certain four item quantitative determination sequence is made.

This determination sequence is fully described hereinafter. A single such four item sequence yields much valuable information and is deemed to lie Within the method of the present invention: but information of much more versatile and valuable nature can be derived from a related plurality of such determinations when taken at the same temperature (or other reaction influence) or at stepwise or continuous changing values of temperatures or the like.

-Upon completion of a first four item sequence, valve means 60 is operated t0 flush the interior 0f the system with gas from external gas source via gas inlet 5, and to bring interior pressure to the orignal predetermined norm value, here atmospheric pressure. lf reaction influencing conditions are to be changed they are best changed at this point in the cyclic operation of the machine. For example, temperature of sample 20 can be elevated by a predetermined temperature increment, and this can be controlled automatically or manually. A new sample can be taken in automatically, or introduced manually. When the reaction has become stabilized in the new situation, and again gas flushed and equilibrated, the machine interior is again closed by valve means 60, and a new four item determination sequence is taken. Automatic sampling means being lwell known, they are not illustrated nor claimed here.

It is preferred in routine reaction rate studies that, as to duration of its items or parts each such determination sequence be essentially a replicate of each other. This is readily achieved by replicate operation of the indicated timing means 70 described.

The operation of the machine, then, consists essentially of the conduct of a series of such unit sequences and using of the results: but in order to achieve useful accuracy a much refined form of the machine must be used.

The process of a single relatively simple determination sequence of the method of the present invention is now described in detail. Firstly, when the reaction has been brought to a uniform and regular rate and condition with respect to reaction-influencing conditions, the interior cavity of the machine is closed. Temperature or other infiuence of reaction is first sensed for an interval of time, here three minutes, as a first item of a sequence. Gas pressure within the closed interior of the machine is then sensed and, conveniently, transmitted to means by which it is translated into symbolic form or otherwise used; and preferably this pressure is automatically recorded during a brief standard interval. A representative such interval is one minute. This sense and, usually, record, becomes the second item of a unit sequence. The reaction under study is permitted to go forward while, thirdly and immediately, at least one reaction-influencing condition ambient to and influencing the reaction (for instance, temperature) is sensed for a brief, standard third interval, for example, three minutes; the resulting sense being, conveniently, transmitted to means wherein it is recorded or otherwise translated into symbolic form and used for the entire said third interval. This, then, becomes the third item. Fourthly, and also immediately thereafter, gas pressure is again sensed, transmitted, and translated, for example automatically recorded, during a final interval of the same duration as the prior gas sensing interval, and this is the fourth item. After such final gas pressure sensing interval the four items of information comprising the indicated sequence are complete. While a four-item sequence is considered to be typical, sequences of fewer or `more than four items are also sometimes tatken and to the extent that they embody simple application and extension of the axact procedures of the present invention, by routine adaptation of the present machine or of its operation, they are deemed to be within the present invention.

r17H-E INFORMATION AND ITS TERMS In the present specification and claims, the recorded or otherwise translated `quantified value (which is to be understood as the Whole range of all the instantaneous values, continuous or discontinuous, finite in number, or infinite, or any brief part thereof), ascertained over a definite interval of time that has a practically common terminus with at least one other time interval during which another quantified value is ascertained, is called an item. Thus a recorded temperature item indicates the range of all the instantaneous temperature values recorded over a definite unit time interval.

More than one item, when interrelated and taken together, constitutes a sequence. A typical sequence is composed of four items of which the first and third are of a reaction influencing condition, and the second and fourth are of gas pressure. More sequences than one, when interrelated and taken together, in respect to the same sample, constitute a series. Typical series have comprised from two to a hundred or more sequences.

The method of the present invention, and in particular the organization of a four item information sequence which is employed in one of the best embodiments of the present machine to practice the method of the present invention will be better understood by reference to FIG. 2. FIG. 2 illustrates a conventionalized graphic record of one such sequence composed of four items of sense. The horizontal distances are functions of elapsed time: vertical distances are functions of a `quantified parameter: here, either gas pressure or reaction temperature, depending upon what the machine is connected to record: distinguishing between the two is not diflicult.

More particularly, in FIG. 2, curved lines B-C and F-G designate record lines such as are traced by an automatic recording device connected at command of timing means 70 with pressure sensing means 90 that is in operable communication with the interior cavity of the present machine in operation and with a reaction of sample 20 in progress. When juxtaposed with D-E, each of B-C and F-G is an item, as are DE and the projection of A*B. Point A indicates pressure reference norm, not recorded, and, in a preferred method of operation will be of a value from which each successive sequence pressure of a series begins. The broken line A-B indicates the assumed pressure values during time for the time projection of A to the time projection of B. Output intelligence from gas pressure sensing means was not then being read. During this time, reaction temperature is being recorded. As the reaction to be studied goes forward with evolution of gas, the interior of the said machine being closed, pressure of gas within the said machine increases as a function of the progress of the reaction studied, as is here indicated by the upward slope of lines B-C and F-G and by inference, CG. This increase continues throughout the time that is represented on the horizontal scale from the projection of point A to the projection of point G. Temperature readings are taken also during beginning and ending liush intervals, here a minute each, but usually these flush interval readings are disregarded.

on a vertical scale, is typically positioned as here shown,

away from the pressure record scale, to avoid confusion. Line D-.E in FIG. 2, as it is straight, indicates the maintenance of a steady temperature throughout a time interval, here three minutes, as the reaction goes forward. Vertical position of this trace in respect to temperature scale, indicates the `quantitative value of the reaction teniperature during the time that there takes place that part of the studied reaction which gives rise to gas pressure change B-C and F-G. Other reaction influence than temperature may be recorded simultaneously or alternatively or by a sequence of more than three items.

At time indicated by point E upon a horizontal time axis the connection of the recording unit is again at once switched by timing means 70 to operative contact with pressure sensing means 90 and, during the next interval, here a minute, a second pressure sense item, indicated by line F-G is recorded.

Extrapolation is the projection of G on time axis, of the quantitative value (on a vertical scale) of Line D-E is reasonable when Line D-E (as here) indicates a relatively steady condition, presently constant temperature, or temperature change at a regular rate, or similar extrapolable value of some other parameter.

Assuming reasonably good control means, it may be assumed that temperature extrapolation from the time of Point A, projected, to the time of Point G, projected, will be reasonably accurate. When such extrapolation is in serious doubt, only the pressure records of Points C and F and the included temperature trace D-E need to be relied upon. These require no extrapolation. In this way, the iirst item of the sequence is not used. Best results are usually obtained when relying upon pressure readings of points C and G, and extrapolating temperature from D-E to the projection of G. While the curve shoulders at B and F are sometimes indistinct, the pen travel away from points C and G has consistently given Well-defined points C and G.

Those skilled in the arts of physical chemistry will immediately recognize that the pressure increment considered in respect to the rtime increment Within which it occurred gives preliminary information as to the rate at which the reaction was then going forward. A single such four item sequence permits determination of the rate of reaction under the then employed conditions. It is often desired to learn not merely the rate of a studied reac- .tion at a single value of reaction-influencing condition but rather the general relationship of rate of reaction to such values over a substantial reaction-influence range. In the instance of many reactions such general relationship can be learned by the conduct of two or more unit determinations for each such reaction to obtain a series of two or more ldata sequences, and thereafter tting to the resulting points a curve having a formula. Any degree of accuracy desired can be achieved by the conduct of enough determinations that the points thus ascertained admit of simple, geometric curve fitting.

In FIG. 2 the pressure increment represented by the projection onto vertical scale of Points C and G (or other points if desired) may be regarded as defining a pressure increment unit AY, whereas the projection of the same points onto horizontal scale may be regarded as dening a related time increment AX.

FIG. 3 indicates a series of idealized item sequence traces of the sort produced in the operation of the present machine. The sense sequences are indicated by Roman numerals. Sequence I, comprising pressure determinations H and I with adjacent temperature determinations is in the nature of a blank. This blank is routinely carried out prior to operation of the machine in order to ascertain that it is operating properly. Any significant change between first and second pressure items indicated here as items H and I, especially under superor sub-atmospheric pressure, would suggest that the closed, interior of the machine is not gas-tight, but is leaking. Other anomalies indicate improper other operation of the machine. Upon the completion of a blank deemed to be successful, here shown as sequence I, the machine is operated through another sequence without sample, and, during the included, or second temperature sensing interval, here 3 minutes, the interior volume of the machine is changed by a known amount by the operation of calibration means 120 as described. Characteristically, the volume is 4diminished by a known amount giving rise to an increase in interior pressure of the machine as would operation with a reacting sample that evolved as gas. However, When a reaction consuming gas is to be studied, then machine interior volume may, if desired, be decreased by a known amount. This known volume change of the machine indicates a difference between the rst and second pressure senses and by correlation of `the graphic or other record of the machine operation with the known change in volume, it is possible easily to convert the graphic record into desired units of gas evolved or consumed. These units may be cubic centimeters, the unit most commonly employed to the present time in operation of the machine as being the most convenient; but the unit difference indicated in the interior pressure may also be expressed as height of a fluid column, such as mercury column; or in terms of bars or millibars, or, by simple chemical calculation may be expressed as a molar fraction of gas evolved or consumed or of sample affected by the reaction under study. Thus, a volume change of 2.24 milliliters represents 0.0001 mole, except for correction to standard conditions. This is illustrated in sequence II, by the difference between items J and K, representing a known decrease in total interior volume. When a continuing or repetitive study is to be made on a reaction of a single sort pressure change can be expressed in direct chemical terms appropriate to the known reaction.

This calibration prior to conduct of a determination has conventionally been the sole calibration for pressure sense within the machine. However, such operation is not essential or critical, and pressure calibrated in suitable other ways or other known manners of recording and processing pressure intelligence are readily employed.

Further, in FIG. 3, the sequence determinations III, IV and V are set forth to illustrate idealized but otherwise typical appearance of traces derived from operation of the machine. It will be noted that, in these successive determinations, at points L, Q and V, corresponding to the beginning time of a given sequence determination cycle at which the interior of .the machine is caused to be closed gas-tight and pressure change begins to take place as a result of the reaction under study, the machine interior pressure is reference pressure, the same in each instance. By the time indicated in points M, R, and W, significant pressure increase has taken place. These points must not be mistaken for reference pressure which, when the studied reaction evolves gas, is lower. The increasing slopes indicated by Lines L-P, Q-U, and V-Z, indicate an increasing rate of reaction. It will 4be apparent that the rate of reaction is indicated graphically in this way by the steepness of the slope.

In routine laboratory use, the machine is equipped with a barometer (not shown), which may be an anaeroid barometer, an anaeroid barograph, or when very accurate Work is being done, a compensated mercury barometer, with which periodic measurement of atmospheric pressure can be made. This measurement of atmospheric pressure can then be used to correct graphic readings for differences in actual reference pressures from which each sequence begins. Changes of atmospheric pressure are seldom so rapid under laboratory conditions as to necessitate readings of the barometer more often than once an hour.

The points indicated in FIG. 3 by letters N and P, S and U, and X and Z, are the preferred points between which to ascertain the pressure increments. However, when desired, other such points may be used. It will be noted that the slope of the curve is, on Cartesian coordinates, a positive slope when gas is evolved. Assuming instrumentation essentially the same as is here implied, a negative slope is evolved when the gas is consumed. The availability of such data for mathematical treatment is at once evident. By appropriate instrumentation gas consumption can be recorded as a positive slope.

A sequence need not be restricted to four items. FIG. 4 illustrates an idealized eight-item sequence. Timing means 70 is suitably adapted, as by changing cam shapes of cams required in the production of the sequence of FIG. 2, and addition of another cam and associated camoperated switches wihereby a third kind of information, here magnetic flux, is sensed, and the resulting electric current values are processed, here translated into tracings on a graph.

Referring more particularly to FIG. 4, it will be noted that an axis of scales of values of, reaction influencing conditions, here, respectively, temperature, pressure, and magnetic ux, is provided as a vertical line shown at the left. This may be calibrated or, more commonly, calibrations are printed over the entire surface of the moving paper tape upon which, in one desirable embodiment, such sequence is traced by one form of intelligence processing means 140. Also, it will be noted that time is indicated on a horizontal scale here shown at the bottom.

LOn this idealized sequence graph, the information items representing values of the three parameters are shown spaced well apart. In practice this is not difficult to achieve, by selection of sensing elements, or biasing their operation or, depending on the instrument, programming the instrument that translates electric output into graphic information. By way of example, some kinds of instrument do not trace a pen line, but rather present a series of small marks that superlicially appear to be dots which, upon close inspection, are found to be imprints of small numerals. Each numeral represents data of one kind, or from one source; by tracing a line through the recurring appearances of a selected numeral the line pertinent to only that data can be graphed.

As to the detailed interpretation of the information in the sequence of FIG. 4, with respect to the process from which it was derived, in operation of the machine of the present invention, at the projection of point A onto the time scale, the timing means 70 has connected intelligence processing means '140 to process, presently to make graphic record, of temperature of reaction during a iirst interval of time, here a minute. Because this data was derived during a rst minute after initiation of a sequence while the sample is being flushed with gas, the possibility exists that the temperature and gas-pressure, reflecting the rate ot reaction, may thereafter be anomalous until some kind of equilibration has occurred.

At time A', gas flush has been discontinued for a second interval of time, presently a minute, and temperature of reaction is usually stable, meantime, gas pressure has become reliable.

At the time corresponding to the projection of A onto the time axis, timing means 70 operates to disconnect temperature sense from, and to connect magnetic flux sensing means 175, which can be of any desired sort, to intelligence processing means 1'40: in the instrument presently in use the pen travels to a new point, here Al and, for the next minute, traces a graphic indication of the measured magnetic ux. The one minute interval here shown is chosen arbitrarily; longer or shorter times can be chosen; and from recording of magnetic ux the instrument can, if desired, be connected to proceed immediately to recording of gas pressure. However, as indicated in FIG. 4, at the end B" of a minute of recording magnetic ux the instrument again, at B', records reaction temperature for a minute. Thus three minutes have elapsed during which any unsteady aspects of the reaction can have passed -and a steady reaction rate can have de` veloped. Again, this three minute initial interval is chosen arbitrarily. When more rapid determinations are desired, it can be shortened considerably. Further, moderate irregularities in reaction rate, typically, do not cause the derived data to be useless.

FIG. 4 indicates that, upon completion, of a minute temperature sense item, a minute magnetic ilux sense item, and, at the projection of B, a second minute temperature sense item, timing means 70 connects appropriate portions of the machine to record, as at line B-C, for a minute, the pressure of the circuitous interior of the machine. The exaltation of point C over point B` on line B-C, on the pressure axis, reflects pressure rise as a function of the reaction during time between the projections of points B and C of sample 20. It is noted that equally valid data are derived by a fall in pressure reflecting consumption of a gas rather than its evolution. The scalar value of the projection of IB-C on the pressure scale is the aspect of line of item B-C which yields reaction information at this juncture. However, in rate studies for 10 which the machine and process are intended, better data are otherwise derived.

At time represented by the projection of point C on the time axis, timing means 70 operates to disconnect pressure sense recording and to connect again temperature sense recording; the pen travels rapidly to point D and, for a minute, D to DA, records a reaction temperature item. As temperature record just prior to pressure sense at point B and just after pressure sense at point C are the same, it becomes reasonable to interpolate that the temperature remained essentially constant during time interval B-C.

During time represented by DDA, an item of temperature is recorded. Thereafter, during time DB-DC, an item of magnetic ux is recorded. Again temperature is recorded from time DD to time E.

Throughout all the time so far discussed, and all the time represented between the projections of A and G of FIG. 4, the machine has been closed to egress or ingress of gas, and pressure change quantitatively reflects the reaction of sample 20. At the time represented by the projection of either E or F (which are essentially the same time) timing means 70 connects the necessary parts of the machine to record an internal pressure item for a minute represented by the projections of F and G.

At time G, item F-G has been recorded, and the sequence of eight items of three parameters has been completed. A one minute Hush, with non-critical temperature recording during it, follows time G and the reaction cycle with its information sequence is complete.

In this whole sequence, for purposes of relating pressure change to other measured factors, it is most preferred to derive pressure readings from points C and G; at these points the sharp reversal of movement of the tracing pen gives rise to an unambiguous point. In other kinds of intelligence processing means, other indicia may be of greater value.

At the conclusion of the sequence, timing means may be so designed and connected that the next sequence duplicates the one just completed except as, through sarnple exhaustion, autocatalysis, and the like, different gas pressures are recorded. However, if desired, the timing means may also operate so that, upon the completion of a sequence, a used sample is discharge and another taken in for study; or changes of predetermined value and direction are brought about in, for example, temperature, magnetic ux, or the like, to give rise to new conditions under which the reaction is to go forward. It is noted that the change called for by operation of the machine should be of a value which the machine can accommodate; thus any increase in temperature of reaction asked of the machine should not be greater than can be brought about by operation of the heating means of the machine during the time interval available. In one working embodiment, it has not been diflicult to bring about a C. reaction temperature rise, in the temperature range of 0-500" C., during a three minute initial temperature item period. The capability of any individual machine will depend upon design factors that are readily aecommodated to individual situations.

It is possible also to operate the machine under rapidly changing ambient conditions. In this situation, not the capacity of the machine to change such conditions as heat, but the responsiveness of the various sensing means and their ability accurately to sense and transmit quantified information determine the response rate of the machine.

FIG. 4 shows, at the right-hand end of the graph, a rising solid temperature line and a rising broken magnetic flux line, by which is indicated that, conveniently, upon the conclusion of a sequence, these values can be changed. It is noted that the data best relied upon are the data taken near to the end of a sequence; hence irregularities occasioned by a change of ambient condition early in the sequence have opportunity to equilibrate, before there would arise any adverse effect upon the validity of the data. Anomalous early data items can be disused.

It will be evident that the number of parameters of which the quantified values can be measured simultaneously is essentially unlimited.

The taking of measurements in this intermittent process from 'which is derived a series of multi-item sense sequences oiiers numerous unique advantages and is essential and critical to a preferred form of the novel method and to the operation of' the best embodiment of the machine of the present invention of which the inventors now know.

REFINEMENTS OF THE MACHINE Reference is made to FIG. 5.

Chemists will at once recognize that, in the best present embodiment, the gas pressure sensed in the second gas pressure sensing interval will differ from that sensed in the first such interval by only the pressure increment or decrement occurring duing the time between. In general, this increment or decrement tends to represent an amount of gas that is small relative to the volume of the internal capacity of the machine. In this situation, when measuring evolved gas, in a reaction that evolves a gas, appreciable proportions of such relatively small amount of evolved gas would, in conventional gas measuring equipment and apparatus, including the primitive proto type machine hereinbefore described, be lost by sorption and the like, with resulting serious inaccuracy. In fact, early attempts in completion of the present invention failed of necessary accuracy because of such sorption. The practicable embodiments of the present machine completely overcome this source of error by providing that the interior cavity of the present machine is, during all critical times, including particularly all times of lboth measurement and evolution of gas to be measured, maintained in the condition of being uniformly saturated with gently moving gas. Ordinarily, the moving saturant gas is, most preferably, identical with the evolved gas. The saturant gas should be caused to reach all parts of the interior, gas-containing cavity of the machine uniformly, at all times including the time such cavity is closed. This condition is conveniently met if the machine interior be provided with a gas-circulating pump and the machine be so constructed that such interior cavity is of circuitous nature or form. This cavity may consist in fact, and in various satisfactory embodiments has consisted, for the most part, of laboratory tubing of metal or glass, connected so as to define a returning, circuitous interior space of the total volume of which the said tubing constitutes a substantial or a major part. Because this embodiment of the circuitous structure has given results far more accurate than those obtained in any other yet studied by the inventor, and because accuracy is essential, it is regarded as essential and critical to the present invention.

In the preferred operation comprising recurring sequences each having a first item representing temperature, a second item representing gas pressure, a third item representing temperature, and a fourth item representing a second gas pressure, all the said intervals essentially adjacent, various procedures must begin and end under relatively accurate time control. While the timing of these operations can be carried out under personal human control, such control necessitates constant attention to the operation of the machine, is expensive and monotonous, and tends to introduce avoidable elements of possible error. In the best and preferred embodiments of the present machine, the control of most or all of recurring operations of the machine, after it has first been placed in operation, are under automatic control of timing means. Such automatic control is established and maintained more easily when all related and subordinate operations are carried out electrically or electronically than in any other manner now known. Hence in all the presently operable embodiments of the present machine, the machine is supplied with areacting sample 20 of which the reaction to be studied evolves or consumes a gas and the machine is then placed into operation: but subsequent operations during and within at least each single operating cycle (that is, while a single sequence is being recorded) are electrically or electronically controlled and all sensed intelligence is transmitted and processed electrically or electronically to the conclusion of such operation as is automatically controlled, at which time it may temporarily be disused, or taken out of operation indefinitely. After a temporary disuse for a predetermined interval of time, it can again be put into use automatically if desired.

Such electrical operation is so versatile and accurate that it is regarded as critical to the best forms of the machine. However, mechanical linkage controls and springwound or airor water-driven mechanical power sources and the like can be used.

As is true with most instrumentation, the intelligence derived from the operation of various sensing elements of the present machine can be transmitted by any of a number of known means to other elements of the machine for translation or other processing. In a model designed for routine laboratory use, connections are made by insulated electric wires. However, when the machine is to be operated upon a sample in an inaccessible or dangerous location, or a plurality of machines are to be operated more or less simultaneously, from different places, the quantified electric form of the intelligence sensed can be converted in Various known Ways into electrical energy varying as a function of the sensed value, and this, in turn, can be sent by electric wires, transmitted as modulations on a modulated or interrupted unmodulated radio frequency of any desired wave length. It can be used to modulate a light beam including the beam from a laser and, by any of these means, be transmitted to any convenient place for further processing, storage, translation, interpretation, or use.

Such information can be processed into any of a great variety of forms. One such is a form to be read directly, as a quantified electric current to be read on a meter which may be essentially a galvanometer, connected in circuits suitable for the reading, by a human operator, of various chemical data directly. If desired, the readable translation may be made by way of a cathode ray oscilloscope, the tracings' of which can be photographed or televised. As an additional or alternative form, the intelligence from the sensing elements can be, and in a preferred embodiment is, translated into desired symbols, usually graphic symbols, and recorded. Whenever the sensed intelligence is converted into the form of electrical energy of which some quantified characteristic represents the quantity measured by a sensing element, it becomes possible to transmit, store, process, and exhibit or distribute, and employ this quantitative intelligence further, in ways of the utmost variety and versatility.

For some work, especially in inaccessible or dangerous locations, where samples may be taken in, a reaction rate can be determined, a sample discharged and another sample taken in for a repetitive sequence, by the use of known automatic sampling means, and especially where sensed intelligence is telemetrically sent, perhaps froma plurality of instruments.

The machine may be used in inaccessible or dangerous locations, with automatic provision for taking in, studying, and discharging a sample by the use of known sarnple changing means. In this situation, a number of instruments may be employed more or less throughout the same period of time as in atmospheric, oceanographic, and similar studies of regional extent. In such situation, it may be desired, and it is within the purview of this invention, that the telemetric or similar equipment be suitably provided with limiting circuits so that only signals above a certain threshold value are transmitted. Thus nonsense data can be screened out. This can be done in conjunction with various memory circuits such that lateemerging sense data can be transmitted conjointly with desired previously untransmitted environing data Withheld from transmission as nonsense. Also, data can be sensed and recorded on a time base, as on a magnetic tape, stored if desired, and thereafter transmitted at a speed other than, usually faster than, that at which it Was recorded. In this manner it is possible to operate the reaction sensing portions of the present machine over an extended period of time and thereafter to transmit the data accumulated in a much shorter period of time. Thus the time of expensive cable or telemetric circuits can be used more efiiciently.

In such use, one unit, typically comprising `gas source 50, gas inlet 5, sample receiving means 10, sample 20 (which may be a standardized sample, perhaps a biological sample, sent with the portions of the machine, or may be admitted automatically at a remote location), gas-introducing means 25, reaction temperature sensing means 30, rate of flow meters 55 and 56 which can be automatic rate-controlling rate-of-fiow meters, valve means 60, outlet 65, pump means 75, pressure sensing means 90 and associated refinements, timing means 70 or the instrumentation making up part of it, cooling means 11S, calibration means 120 or a closable port at which such means is detachably attached, intelligence processing means 140, or portions thereof, or telemetric or the like means for operably coupling other portions of the machine with intelligence processing means 140, heating means 155 and means 145 and 150 for its sense and control, if desired; and like parts as herein shown and described as pertaining to the processing and sensing of response in the sample 20, together with a suitable energy source can be in one location. Telemetric or similar means can be employed to couple these portions of the machine with such other portions as timing means 70, or portions thereof; intelligence processing means 140 or portions thereof, and other portions of the machine concerned primarily with manipulating, and controlling the manipulation of data. So long as the essential cooperation of the parts is maintained as herein described and claimed, the mere segregation of the parts into groups connected by wires or telemetric means is Within the scope of this invention.

Thus, the intelligence electrically sensed in the present machine can ultimately be read on electric meters, can be recorded on paper discs, belts, magnetic tapes, punched cards; scribed onto smoked discs or drums, or fed directly into a computer or computers programmed to receive, store, and retrieve, such intelligence and deal with it in various ways. It may also be used, unmodified or in cooperation with data norms of reference, directly or after recording and subsequent retrieval, to control, in Whole or in part, the further operation of the present machine or the operation of an industrial process.

Thus, the data derived from operation of the present machine, processed through intelligence processing means integral with or separate from other parts of the present machine, are readily presented in a form useful in the control of chemical and life processes on a laboratory or industrial scale. The present machine in this way finds application in automatic apparatus for the control of chemical processes and the like.

Because the sensing elements deriving intelligence from various aspects of the operation of the present machine are independent of one another, their output, in the form of quantified electrical output, can be fed into separate symbolic translation means such as graphic recording instruments. When this is done, it is necessary to use precision means to interrelate the data. For example, it is possible to provide some calibrated and identified time base common to all resulting correlated data records whereby the various data can be exactly related to one another as to time. This can be done, as by synchronizing time pulses and the like. Also, multiple intelligence processing means can be employed simultaneously: as a graphic recorder and, for instance a high-precision galvanometer or an overload alarm indicator.

In at least all employment of the present machine in which, critically, one or more sorts of data is to be treated graphically as a derivative of one or more other sorts of data, it is preferred that all correlated data, if it is to be graphically recorded, be recorded in short sequences of items, a plurality of such sequences occurring as series, eventually all on the same graphic record, whereby the common time reference to data on one or more data reference axes is unequivocally established.

This preferred form of graphic record offers the advantage that the time relationship of time-related data cannot be lost. Moreover, when a graphic record is made, the simplest of graphic analyses permits ready and satisfactorily accurate determination of the information usually sought in the operation of a machine of the present invention.

Moreover, the periodic interruption of the process of sensing of the pressure of the gas facilitates the recurring reference to a pressure norm, by which the best embodiment of the present process is made possible.

When operating the machine continuously (that is, without the periodic selections of various instruments as described), in a manner that is not preferred, and with separate continuous traces for the several kinds of data involved, a common time trace can be introduced by any of various means. In one such, the reaction-responsive gas pressure is regularly, intermittently returned to the previously assigned norm, and simultaneously with the resulting features characteristic of the record thereof, a time marker pulse is introduced into any other records simultaneously being made on other devices. Proper synchronization of the time traces thus provided makes possible derivation of correlated data from records not kept on the same chart or the like.

A timing mechanism susceptible of ready adjustment to time intervals accurate within a second, that causes the timely operation of various sensing and reaction-ambient condition control means is also readily used, and in a preferred embodiment of the present machine has been regularly used, to cause the correspondingly timely operation of controls of the means to establish, maintain, change, or measure, conditions that inuence, or results that occur in, the course of a reaction.

Accurate determinations of small changes in gas pressure from a reference pressure which may be any pressure within a considerable range are of critical importance in the operation of the present machine.

The present machine should preferably present intelligence that is linear on at least some coordinate system with respect to linear functions. To do this it should comprise only such operating members as can operate in necessary ways without causing significant uncompensated gas pressure changes in the interior cavity of the machine. One fertile source of trouble can be an inappropriate gas pressure sensing means, notably a means that, as it senses, changes significantly the pressure that it senses.

Hence, an electromechanical transducer is preferred to a mercury manometer as a pressure sensing means, because operation and corresponding displacement of mercury of the mercury manometer (or other iiuid manometer) represents an interior volume change that is very significant compared to the interior volume of the machine. While it is theoretically possible to correct, manually or automatically, for manometric volume changes, the introduction of error becomes very probable: this form of construction is outside any preferred embodiments of the present invention. In contrast, when a typical electromechanical transducer is employed, any cavity volume change resulting from its full scale operation is very small and any resulting nonlinearity of data has been ignored Without serious inaccuracy.

The circulation of gas throughout the interior of the present machine has been noted. This is typically achieved by pumping the gas during at least part of each sequence.

In this regard it is pointed out that a pump is of use precisely because it causes changes in pressure. To the extent that such changes, typically intermittent and recurring changes, caused by pump operation are sensed by gas pressure sensing means 90, they represent useless, typically troublesome, non-data senses.

Now that the problem is delined in context of the presentmachine, those skilled in instrumentation arts will at once recognize that any of a number of expedients may be used to overcome the problem of sensin-g of meaningless recurring pressure changes caused by pump operation. One such that has been used successfully is the inclusion of a cavity chamber in the nature of a muffler or resonator, tuned or untuned, at such point in the circuitous machine interior cavity that the elasticity of gas within it mechanically damps and neutralizes reciprocal or oscillatory pressure changes caused by pump operation. More simply, and preferred, an electromechanical pressure sensing transducer is used, which either by reason of its inherent properties, or by reason of the properties of an associated electrical circuit, does not respond to pressure changes that occur at or about the frequency rate at which the pump-caused changes occur; in cornbination with a pump of which the operation is at a rate such as to cause any pressure fluctuations at frequencies quite different from those of the sensed operation. In general, the use of a pump causing relatively high frequency pressure pulsations of low amplitude, in combination with a pressure-sensing transducer that will not respond at a frequency as high as the pump pulsation frequency, has been the most satisfactory embodiment presently known to the inventor. Pressure pulsations of high amplitude, whether sensed or not, are to be avoided because of possible disturbance of instrument adjustments or damage to equipment.

Both as to accuracy of results and as to convenience in sample manipulation, it is hi-ghly desirable, and, for accurate work it is usually critical, that the rate of gas circulation caused by the operation of pump means 75 should be essentially the same as the rate of gas movement caused by introduction of gas from gas source at gas inlet 5. When the rates are essentially identical, little or no fluctuation in interior pressure is occasioned upon the operation of valve means 60, in selecting the internal pump or the external gas source, as cause of gas movement. When the two rates differ by more than an insignificant amount, changing the gas flow from one to the other may be accompanied by spattering of sample from the sudden pulse of gas through Igas introducing means 25. Moreover, it appears that the equilibrium gas distribution Within the machine that is critical to accuracy is a function of, among other inuences, the rate of gas flow; having both causes of liow equal avoids disturbance of this equilibrium.

The rate of flow caused by operation of pump means 7-5 is readily adjusted by controlling the dimensions of the pump itself, introduction of a pump output valve or like means, or controlling the rate or amplitude of pump operation, and the like. In a preferred embodiment that has worked well, the pump is a diaphragm displacement pump, of which the movement of the diaphragm is caused by the camming action of an operably connected adjustable eccentric on a motor-driven shaft. The size, shape, and rotational speed of this eccentric have been adjusted to give a diaphragm displacement of which the average pumpout was at a rate equal to the rate of gas input from external `gas source, each being measured at a time and in a portion of the circuitous internal cavity to give a reading representing a uniform, steady value.

Readings of each source of gas liow can be taken by the use of a separate conventional rate-of-flow meter to read each rate. Standard rotameters (FIG. 5) 55 and 56 comprising small weighted spheres floating in a tapering upright calibrated gas duct are satisfactory. For -convenience, the meters are best mounted side by side so that, without necessity for taking a numerically quantified reading, one can simply observe that the floating balls of which the position designates the meter reading are oating in essentially side-by-side relationship. Other rate of flow metering means can be used. To avoid introduction of undesired foreign matter such as matter from the sample 20 or portions of solvent or the byproducts of reaction, and the like, a most preferred location for internal rate of liow meter 56 in machines hitherto produced is at a portion of the circuitous interior cavity between gas pressure sensing means and the tubing line to gas introducing means 25. This is illustrated in FIG. 5. From this point in normal use, the immediate ow of gas is either through the bypass if a bypass and manifold are used, or through the sample. The meter 56 is thus at a point at which rate of flow is either through the bypass or through the sample. The meter 56 is thus at a point at which rate of ow is most significant but the meter is most remote from the most common sources of congestants.

The effect of changing temperature imposed upon the reacting sample would, in gas-pressure sensing reacting study devices known to the prior art, be expected to give rise to gas pressure changes approximately predictable by the gas laws, that would at least have to be compensated in calculating the significance of the data derived in operation of this machine. Similarly anomalous readings would be expected from temperature differences at different parts of the machine. This and related effects are indeed apparent when the present machine is adjusted to operate to sense pressure (and therefore pressure change) of evolved or consumed gas continuously over an extended period of time and through a range of changing reaction temperatures, without cyclic recurring reference to a norm. However, such continuous operation is not a preferred manner of operation. Any inaccuracy due to, or need for special compensation or correction for, pressure change due to temperature change including notably reaction temperature change, is eliminated when the sensing means of the present machine are operated in the preferred, norm-referrent, intermittent manner, hereinbefore described.

In practice, information developed with no compensation whatsoever for temperature variations and fluctuations has been consistently free from error of discernible proportions, even in work of relatively very high precision.

A substance evolves gas when it boils. The present machine is sensitive to the evolution of gas. A substance in effect consumes gas when it condenses from vapor to liquid. The present machine is sensitive to the consumption of gas.

When cooling means is of suflicient capacity, boiling can be essentially ignored. The necessity for great capacity in cooling means 115 can be reduced if care is taken in known ways to prevent the sudden ebullation known as bumping that results from local overheating of a heat-exchange surface. This bumping manifests itself in readings of the machine as noise when not cancelled by capacity of cooling means 115, or otherwise.

Work up to the boiling temperature has presented no special problem. Work above the boiling temperature has presented no problem. The only difliculty that merits special attention is encountered when a given series represents a pattern of temperature changes that starts away from and passes upwards or downwards through a boiling temperature. It has often been possible to obviate the problem of boiling or condensation by altering ambient pressure, to lower or raise a boiling point of a substance studied, uniformly throughout a series of traces. Now that the problem has been stated and means for dealing with it have been pointed out, instrumentation technicians will have no diiculty dealing with it.

When it is desired to study the response of a reaction to changing conditions of which the pressure reference norm is a non-atmospheric pressure or to pressure that is atmospheric but not terrestrial, machine operation and in particular the operation of pressure sensing means at non-atmospheric pressure is made much easier and more accurate by mechanical compensation of the pressure sensing means for the non-atmospheric base or reference pressure than in any other way known to the inventors.

When employing the preferred embodiment of pressure sensing means, namely an electromechanical transducer, it will be noted that such device comprises walls defining an enclosure, an entry port thereto and having a stretched diaphragm sensing member which, together with all associated parts and mechanical mounting, is gas-tight and deiines part of the enclosure and communicates with the circuitous interior of the preferred form of the machine. Such transducer, without more, typically has atmospheric pressure which need not be a terrestrial surface atmospheric pressure upon one surface of its diaphragm that is exterior to the circuitous machine interior, and machine interior pressure upon the other. When each determination begins by reference to atmospheric pressure, such arrangement is fully satisfactory, because sample size and other readily controlled factors can be so adjusted that no interior pressure departs from atmospheric by a value greater than the operable transducer pressure range. However, further detail of construction of certain commercially available transducers `greatly facilitates operation at non-atmospheric pressure: namely, the provision of gas-tight enclosure means adjacent to and cooperating with the back or exterior side of the said diaphragm, and having at least one entry or exit port. When a gas pressure to be measured represents a small change from a reference norm pressure that differs substantially from atmospheric pressure, the said reference norm pressure can, in this particularly preferred embodiment, be imposed upon the said lback side of the diaphragm with the result that, in operation, the diaphragm is stressed by, and responds to such changes as are departures from such reference norm pressure, such changes being imposed upon the diaphragm surface that is interior to the machine cavity. It is contemplated that the employed reference norm pressure will usually be unvarying except for periodic renewal by reference to some convenient norm pressure source. Norm pressure can be a vacuum, essentially zero pressure. It should be noted, however, that the reference norm pressure may vary, if desired, in a measured, or a chosen and controlled time and phase relationship to variations, or some of them, in the sensed pressure of the gas inside the machine. In this Way a timed pulse may be introduced, or undesired pressure variations cancelled.

Because the present machine is more useful when it is more, rather than less accurate, it is preferred for highly accurate laboratory work to incorporate into the machine simple, direct, accurate means, themselves susceptible of standardization, for the essentially exact calibration of at least some of the various instruments and recording devices of the present machine, in addition to the pressure calibration means 120 hitherto described. How this is to be done and with what means is not critical. Any such means may be used in conjunction with the routine instrumentation to provide a calibration chart or graph that makes possible conversion of instrument readings into correlated data items.

Satisfactory means for checking the recording instrumentation of the present invention include thermometers by means of which to check thermocouples, temperature compensated uid manometers to check electromechanical transducers; photosensitive materials such as photographic iilm, without or conjointly with controlled density filters, to check radiation measurement equipment, and so forth. Other means will, in view of the present specification and claims, be evident to those skilled in the art of instrumentation.

SAMPLE RECEIVING MEANS For convenience in changing samples to be studied in the present machine, various sample-receiving means 10` have been prepared of which one form for laboratory use, with associated structures is shown in detail in |FIG. 6. Such structures have comprised gas by-pass valve means 100, gas introducing means 25, sample receiving means 10, openable joint 15 for attachment and detachment of sample-receiving means when introducing, removing, or modifying sample 20; manifold 110, and the half joints for the connection of these parts with, respectively, tubing, connecting with other parts of the machine.

Under some conditions of use, pressure internal to the present machine has tended to urge apart the members of openable joint 15. Headed studs 16 were fused to the parts of the joint as illustrated in FIG. 6. Wires were laced around cooperating pairs of these studs to hold openable joint 15 securely closed. Other means could be used.

Another closely related form of laboratory sample receiving means is illustrated in FIG. 7. Here, manfold 110 and bypass valve means 100 have been eliminated along with the bypass 105. In this embodiment, the function of regulating gas ow through sample 20y via gas introducing means 25 is reflected upon the machine as a whole including particularly the rate of gas How caused by operation of pump means and the interior diameter of tubing which the machine comprises, particularly the tubing connecting from rate-of-iiow meter 56, and the connection with cooling means 115. FIG. 7 illustrates also that in this embodiment, operable joint 15 is closed by a stopper 111, for sample access. Here, glass projections 16 on the stopper and on the main body of sample receiving means 10` provide for holding the stopper in place and joint 15 securely closed. This closure has been conveniently effected by stretching stressed springs from one projection on the body to a cooperating projection on the stopper 111, on each side of sample receiving means 10i.

In various embodiments of sample receiving means 10, rWell 28 was provided entering sample receiving means 10 at a point which, in use, would normally be covered byand immersed in sample 20, wherein to position reaction temperature sensing means 30. Openable joint 15 was standardized so as to permit interchangeable use of parts there connected. Sample receiving means 10 was, itself, embodied variously in vessels ranging in size from small vessels, resembling test tubes, which would conveniently accommodate a few milliliters, to fiasks with a capacity of one or more liters. Also, adapter means can be provided whereby much larger liasks, up to a capacity of 2O or more liters, can be attached. Connection can also be made to reaction vessels of industrial size but for various reasons the direct connection of the machine with such vessels does not usually permit analysis of laboratory accuracy. Various adaptations of the tubing connection are necessary when employing relatively large sample receiving means in order that samples may be positioned upon adequate mechanical support in a position not obstructing access to a vertical panel upon which other components of the machine are typically mounted.

Also, by the use of adapters, sample receiving means 10, and associated structures have been located away from the instrumentation of the machine as variously, under exhaust hoods, in explosion-proof bomb chambers, and the like; 'with tubing connections and adapters providing essentially the structure here illustrated.

Of all these means, the embodiment wherein sample receiving means 10 has a total internal capacity of approximately 250 milliliters has been found, to the present time, to be most commonly useful in the conduct of accurate determinations on a laboratory scale, except in the conduct of biochemical determinations employing living organisms in which instance sample receiving means having a total capacity of about 2 liters have been found to be most useful.

The present machine permits studies of those reaction rates that pertain uniquely to the vital processes of living organisms. Thus an animal can be maintained within the reaction vessel here identified as sample receiving means 10, and the sum of the rates of reactions in its body, as represented by consumption or production of a gas, can be measured. The vessel can be adapted to structures attachable to the respiratory or other tract of a human being to obtain metabolic rate data that is sampled in time, as hereinbefore noted, and admits of sensitivity of determination, especially in view of changing influencing conditions, yielding information unavailable with traditional metabolic rate apparatuses. Also a plant, a population of plants, a terrarium or aquarium, or a microenvironment for a balanced biota can be positioned within a modied form of sample receiving means 10 and the `whole rate of reaction represented by an evolved or consumed gas can be ascertained. In this and other uses, only uncontrolled external reaction ambient conditions, such as room temperature, may be preferred, and the employed gas may be atmospheric. Imbalances in the biota are thus readily ascertained. Also, in fermentations and like biochemical processes incident to which gas is evolved or consumed, not only rates of fermentation, considered as reaction, can be ascertained, but also effect upon such rate of reaction of such varying factors as temperature, nutrient content, light, and the like.

Also, by suitable adaptation of sample receiving means, the present machine can be employed to sample an adjacent air, water, reactor contents, or the like, confine the sample, carry out the processes hereinbefore `described for reaction rate determination, once, or as many times and for as long a period as desired, then discharge the sample, taking in another if desired, and repeating.

It is contemplated that this kind of embodiment, suitably adapted will lind use in assay of waters of natural bodies of water for consumption of oxygen as a measure of decontamination of sewage. It will also be used to assay waters in natural bodies of water for living organisms and their relative abundance by gases, typically but not always, carbon dioxide or oxygen, evolved or consumed. In exploration of celestial bodies other than earth it will be used as a life detector, usually with quantified senses of data telemetered to earth stations for interpretation. On the high seas it will indicate the relative abundance of life forms, presumably small to minute life forms, admitted as a sample through a screen. Suitably enclosed, it can be operated beneath the surface of a natural body of water, as attached to the exterior of a submarine, or with means for taking on samples exterior to a submarine or the hull of a surface vessel; or it can be floated beneath ice such as arctic ice or sunk to a lake, river, or sea bottom at a desired location. Its location can be xed by anchoring or sinking; or it can be permitted to float free and the device electronically tracked by tracking devices that are not part of this invention.

Also it can be mounted on hill or mountain stations to measure and telemeter airborne biota; it can be carried on aircraft.

Given the invention as herein claimed, the taking and voiding of recurring samples automatically is believed to be within the skill of the routineer in instrumentation.

In various embodiments of the instant invention, means have been provided for disusing gas circulating pump means 75 during such time as pressure senses being taken by gas pressure sensing means 90 were being recorded, translated, or otherwise employed; however, continuous operation of gas circulating pump means 75 has reduced the total error of representative determination to about one tenth the error in similar determination when pump means 75 is operated intermittently to avoid operation during gas pressure sensing intervals. Hence, in the present embodiment of the machine, in the preferred method, gas circulating pump means 75 operates continuously, and to the extent that it generates pulsations of gas pressures within the circuitous interior cavity of the present machine, no record is made of them. In one highly satisfactory embodiment of the present machine, gas circulating pump means 75, incident to its function of pumping gas, introduces pulsations of the gas pressure in the said cavity at a rate on the order of approximately to 1000 such pulsations per minute; whereas the threshold upper frequency of pressure pulsations to which gas pressure sensing means 90 responds perceptibly is on the order of 10 to 50 pulsations per minute. In this situation, the frequency relationship of pulsations generated by gas circulating pump means 75 and the frequency discriminatory response of gas pressure sensing means 90 has the effect of integrating as a slowly changing value, responsive to the course of reaction, all the various instantaneous pressures which may be assumed to have existed briefly within the said cavity.

Other useful modifications of the present machine are as follows:

In some locations it will be advantageous to supply power for the operation of the present machine through a regulatory device such as a power supply circuit in which a constant voltage drop tube controls supply voltage when the source voltage is subject to inadmissable variations. Such regulation may be more important in the power supply to circuits comprising biassed sensing means than on, for example, motor circuits, heater circuits, and the like. While the advantage of accuracy gained through the use of such regulatory devices may be desirable, the devices are not essential to the present invention.

Relative to the influences inducing reaction, and the reactivity of sample 20, it has usually been most convenient to employ a sample of such size that only a small fraction of total available reaction occurs during, and is sensed as, one sequence. In most determinations, the apparatus readily and accurately senses and reports reactions of the general order of magnitude of from l to 10 107 gram-moles per mole per second. When the reaction proceeds so fast that the capability of the machine is challenged during a 10 minute cycle, a 5 minute or one minute cycle can be employed. Shorter cycles can be used, also. The rst limiting factor upon maximum reaction rate which the machine can measure is usually diaphragm stress in the electromechanical transducer used to sense pressure internal to the machine. When the reaction goes forward at a rate that is essentially explosive, conventional rate data are seldom sought; but the present machine is not a preferred means of obtaining the data.

When employing a sample that is of the order of a magnitude of 0.1 to 1 gram-mole, very large relative to the per-sequence exhaustion through the measured reaction, sample exhaustion can be ignored through a rate study carried out for as long as 24 hours, representing, nominally, about sequences in a series. Such runs may represent from about 1 to 10X 104 seconds, and it will be seen that sample exhaustion, if linear or nearly so, may be on the order of from 1 to 10X 10-3 gram-moles. As a factor affecting reaction rate data, an uncomplicated sample depletion of this order can be ignored. When total reaction time is even shorter, sample depletion is less a problem.

It has usually been assumed that more accurate data could be obtained from a slowly reacting sample slowly depleted but otherwise undisturbed than from freshly supplied undepleted samples newly introduced into the apparatus and necessarily, each time, brought to reaction conditions.

While means for stirring have often been provided within sample 20, when an oil bath or other iiuid temperature stabilizing means is provided, it can also be stirred. When stirring is accomplished by rotating magnetic field driving a stirring rotor within the fluid to be stirred, one magnetic drive can sometimes operate two separate driven members. Magnetic stirring is preferred as obviating gas-tight glands around drive shafts entering the mechanism from Without.

Cooling means 115 is introduced so as to follow, downstream in the direction of gas flow, sample receiving means 10. This is done in order to condense and in one common embodiment to return to sample receiving means any liquid of which vapors can be readily condensed, and thus remove it from the circulating gas stream. In this Way, it is possible to localize such condensation and reduce accumulation of condensed liquids at undesired locations within the machine. However, less desirably traps and the like can be located elsewhere if desired making due allowance that no irrelevant pressure fluctuations of sensible frequency be thereby generated. Traps are not preferred because they tend to increase sorption inaccuracies.

`Calibration means 120 may be located at any point communicating with the machines interior cavity which is convenient for operators access. The indicated location corresponds to the approximate schematic relative position at which it was connected in one satisfactory embodiment of the machine.

When needed in the use of the present machine there are provided, in cooperation conjointly with back pressure chamber of pressure sensing means 90 and `with the circuitous interior cavity of the machine means for imposing, confining, stabilizing and at a desired time releasing nonatmospheric pressures, typically pressure norms. Such means can comprise imposed reference pressure pump means, valve means, which can be a plurality of separate, cooperating valves, and imposed pressure stabilizing means which in one form can be a pressur chamber, associated with immersed reference pressure pump means or structurally separate. Most conveniently, gas supply at gas inlet 5, and gas release at outlet 65 lwill be provided with means (not shown) to establish and maintain internal pressure. Up to at least about 50 atmospheres, no serious difficulties need be expected, if machine parts are designed for the pressures. Thus while pressure relief means 93 and 94 are seldom needed for atmospheric pressure operation they are desirable for operation at elevated pressures.

By operation of means for imposing pressures, it is possible to study the reaction of sample under nonatmospheric pressures as the sole imposed non-environmental condition, or as one of several such conditions.

When operating pressure is consistently nonatmospheric, calibration means 120 is desirably provided with adjustable locking means so that its employment as well as its rest position are not disturbed by imposition upon the interior of the machine of nonatmospheric pressure. This can be done in various ways; in one way, the plunger of calibration means 120 is secured to an end of a threaded screw which cooperates with a threaded, tapped plate immovably attached to the frame of the machine. Other ways are available. In the present invention, these embodiments are deemed to be substanti-al equivalents of one another.

When operating at consistently nonatmospheric pressures in an atmospheric environment, it is usually desired to avoid the recurring cyclic return to atmospheric pressure hereinbefore described but to return rather to a standardized nonatmospheric norm, or reference pressure. Doing so avoids undue prolongation of the cycle time necessary to restore the nonatmospheric pressure before beginning a next determination, and achieves the reference pressure more accurately. This can be accomplished in various ways.

22 MACHINE OPERATION In the study of a reaction, it is usually desired to ascertain the behavior of the reaction in response to the change of some factor such as the imposition of some quantity or quantities of energy in any or several of a plurality of forms. Because the present machine makes possible determinations of the progress of a chemical reaction with high accunacy during study times that are very short as compared with methods hitherto known, it is possible according to the present invention to ascertain with accuracy the effect, if any, upon the course of a reaction, exerted by an inuence so weak that its effect has hitherto eluded comparison. Reference is now made to FIG. 5.

Various means may be employed for imposing reactioninfluencing conditions of Various kinds typically energy, upon sample 20, as well as for quantitaive sensing of these conditions and their control at desired levels. In any instance, dual sensing means can be provided, one to sense the condition as applied, as basis for its control, the other to sense the condition as affecting the reaction, the resulting intelligence to be used in appraising the relationship between condition and result. Thus ambient temperature sensing means is, in some embodiments, separate in structure and function from reaction temperature sensing means 30, although in operation they provide closely similar readings. When cost, weight, space, or like factors are critical, it is usually possible to use a single sensing element for both control and collection of reaction intelligence. When extreme accuracy is desired, separate sensing means will often be used.

-More particularly, there are provided, as needed, adjacent sample 20, within or adjacent sample receiving means 10, means for maintaining, altering, and measuring temperature, magnetic field, electrostatic field, and radiation as to type, intensity, frequency of change, and the like, ambient to or incident upon sample 20. Pressure in the form of gas pressure can also be controlled at desired levels, as noted above. Any and all of the means for modifying reaction-influencing conditions is, if desired, controlled by, and in cooperation with other functions of, the present machine.

Thus, magnetic means 185 imposes a superterrestrial magnetic field upon sample 20 and the intensity of this field is measured yby magnetic field sensing means 175, through probe which is suitably juxtaposed to sample 20 and cooperatively connected to control magnetic means 185. Suitable pole pieces, typically of a paramagnetic material, can be used to focus a magnetic eld upon sample 20 when employing magnetic energy levels not above the saturation level of such pole-piece material. At the higher levels, the magnetic means shaped so as inherently to effect any desired focus, is directly employed, without core or pole pieces. It is noted that whereas temperature is, in general, scalar, a magnetic field is necessarily vectorial. Thus, it is not universally symmetrical. Probe 180 of magnetic field sensing means 175 1s to be understood as being suitably positioned in respect to the orientation of the magnetic field it is to sense, as dictated by the design and requirements of -magnetic means 185, magnetic field sensing means 175, probe 180, and sample 201.

Magnetic means 185 is assumed to be, if necessary, suitably energized. A permanent magnet can be used when the desired results can be attained in that way. Magnetic eld can be controlled not only as to strength and polarity, but also as to incidence and duration, as well as wave shape of the curve describing the incidence, persistence, and decay of such field. Magnetic pulses can be used. These means are not at the heart of the invention.

Temperature of sample 20 may be controlled directly, as by the use of resistance heating in conductive contact with sample 20 itself or with sample receiving means 10, or by radiant heating as from heat lamps, and the like. Such radiant heating has been preferred -because of the ease with which it can be controlled automatically: but heat from other sources together with appropriate means of control has been and may be used; such as heat from hot-air jackets, vapor jackets such as steam jackets, electric mantles and the like; open flames, such as Bunsen, and other gas burners; supersonic vibrations and shock waves.

A particularly advantageous manner of heating sample 20 has been the use of a moving current of heated gas, most commonly air. In particular, when employing relatively strong magnetic elds as at least a major part of the imposed energy upon sample 20, conventional electrical temperature sensing means and heating coils which, if employed, are within the indicated magnetic field, tend to operate erratically and their successful employment calls for adjustment and other accommodation that may be expensive and time consuming. The problem is greatly simplified or largely obviated 4by heating the sample 20 within sample receiving means by a moving current of air heated at a relatively remote point. and conductively brought to and around sample receiving means by any convenient impeller means not shown. In this situation, if temperature record and control is deemed to be important, only reaction temperature sensing means 30 need be adapted to operate accurately Within the magnetic field, and intelligence from it can be used to control, for example, the operation of a heat source or an impeller transporting heated gas to sample 20 or both source and impeller. The manner in which the air is heated is in no way critical to the present invention.

In an embodiment that is preferred whenever it is convenient to use it, heating means 155 is used to heat a reaction temperature stabilizing means 35. Such stabilizing means 35 is usefully embodied in an oil bath or the like, of which the thermal inertia adds to the thermal inertia of sample receiving means 10 and sample 20; and the stabilizing means also provides a useful locus within which the response is used to control heating means 155 via temperature and temperature change control means 145.

In some determinations `successfully carried out in the present machine, it has been desired to maintain temperature of sample 20 at a temperature as nearly constant as possible, despite the imposition of external influences tending insistently to cause temperature changes but under conditions under which the use of temperature stabilizing means 35 is impractical. In this situation, in one embodiment, a multi-stage, multicontrol heating system was employed, when, in employing approximately 0.1 mole samples, one 250 watt reflector heat lamp was in continuous operation to provide a background heat, a second such lamp was under control of a sensitive thermostat further to elevate the temperature while causing only minor fluctuations in sample temperature: and meanwhile, a short length of resistance heating wire not shown in the present drawing was secured to the outer surface of the wall of sample receiving means 10 and controlled by a very sensitive thermostat not specifically shown in the drawing, to provide for relatively precise control of temperature. The heat sources and sample receiving means 10 have also sometimes been enrobed in reflective metallic foil to confine heat. Numerous similar expedient arrangements of the various present means will be apparent to those skilled in the art, in light of the present teaching.

Similarly, the reaction of sample 20 may be carried out and studied under the influence of radiation. The term radiation herein is relatively broad and covers, generally speaking, all forms of radiation of which the effect upon a chemical reaction is to be studied.

While the precise identity (or wavelength) and relative intensity of radiation from radiation means 200 may be critical in a given reaction, such identity is not critical to the present machine.

Similarly, critical geometric or mechanical arrangements may be required for some certain employments of radiation, but they lie outside the present invention, and those skilled in instrumentation will understand the requirements involved. It is essential and critical that radiation from radiation means 200 with or without reflector means, condenser and collimation means such as lenses, apertures, and the like (not shown) reach and impinge upon sample 20 within sample receiving means 10. Thus, any Vessel wall, or membrane, or other substance as disposed between the actual point at which the radiation is generated or from which it is propagated and sample 20 must be at least somewhat transparent to the said radiation.

In one useful embodiment, sample receiving means 10 is provided of sufficient size and with sufficient means of access to the interior space which it defines, that means for the propagation of radiation (that is, at least critical structures of radiation means 200) are position-ed within sample receiving means 10 and relatively surrounded by sample 20. This is in accordance with routine industrial practice wherein for example, ultraviolet light sources may be disposed within reaction vessels.

However radiation means 200 is disposed and whatever the nature of the employed radiation, when a quantified assay of the radiation incident upon sample 20 is desired, radiation sensing means 205 suitably instrumented as by intelligence processing means 140, is so disposed as to intercept radiation in a relatively xed relation to the interception thereof by sample 20. When radiation means 200 is of a constant nature, as a sample of a radioactive element, shutters and the like can be used to control the amount of radiation that Will impinge upon sample 20.

When the present machine is to be operated automatically, some mechanical embodiment of timing means 70 is necessary to cause the various coacting parts of the machine to perform their related functions automatically in such time relationship as has hereinbefore been set forth. However, even in automatic operation the interposition of human control of time relationships is sometimes desired; timing means 70 may be embodied in manual controls that initiate or terminate the function of the controlled means. In a most convenient embodiment, automatic mechanical timing means are provided; but are equipped with means for manual operation (not shown) also, so disposed that manual operation prevails over automatic whenever the manual controls are employed.

In View of the foregoing description, it will be apparent to those skilled in the art that the lexact nature and identity of individual components of the instant invention and various refinements thereof are not critical. Thus any of a very great variety of meters, recording devices, sensing members, and so forth can be used provided that any component meets such criteria of accuracy and durability as are obviously required, or are herein stated to be essential and critical; and that the machine as a whole combines the indicated functions in the cooperating manner herein set forth. One fully operative embodiment of the present machine, is described below. However, this is one example only and it is to be understood that the present invention is limited only according to the appended claims.

EXAMPLE 1 An automatic reaction rate apparatus of the present invention was made, employing necessary parts front and rear-mounted on a hardboard panel one-half inch thick that was supported vertically by means of stout angle brackets triangular braced from a horizontal rectangular base platform on casters. Gas source 50 was provided as means of connection through a pressure reducing valve to commercially available cylinders of compressed gas of identity selected individually for an intended reaction, the gas being conducted by tubing from pressure reducing valve to the present apparatus. The pressure gauge, pressure reducing valve system, not shown in the present drawings, and assoc'iated tubing, were of stainless steel and materials similarly resistant to corrosion. Alternative gas sources can be connected to gas inlet 5, by connection at various joints, provided but not illustrated.

Rate-of-flow meters 55 and 56 were each a Fischer and Porter rate-of-ow meter commonly called a Rotameter, bearing no model number but about inches high, of which a central tube defining a downward tapering internal axial bore, was apparently a little less than 1A inch outside diameter with an average internal bore of about 1/16 inch. The meter operates by the oat position of a weighted ball on the gas stream in the tapered bore relative to cooperating calibrations juxtaposed the ball position. Outlet 65 was a rubber tube conducting effluent gas to a laboratory hood that exhausted lwith dilution to outdoor air. Val-ve means 60 was a gang of three standard valves, two three-way, and one two-way, their position of operation being under control of separate solenoids operated in gang from a single timing means. Valves of several different standard manufactured brands have been used. Any may be used, reliability and cost being the principal criteria in selection. Pump means 7S was a Dynapurnp diaphragm type pump sold by Fisher Scientie Company, Model 2-ST, modified for the present machine by the replacement of its drive cam with a smaller drive cam to reduce the stroke length and thus the perstroke displacement; and provided with a drive mechanism for operating the pump at a higher speed than that for which it was originally designed.

Gas pressure sensing means 90, comprising an internal pressure sensing chamber and a back pressure, that is, external reference pressure, chamber together with necessary entry ports, exit ports, diaphragm, electric diaphragm displacement responsive means and the like, was a Dynesco PT 14-4 Electro-Pressure Transducer. Manifold by-pass valve means 100 was a simple ground glass valve of standard laboratory design. Tubing not otherwise described in the instant embodiment of the present invention was standard 3% inch glass laboratory tubing or was Superior Tube Company Weldrawn 316 1A inch by .028 ASTM A-269-5 8 stainless steel tubing. Joints, not herein shown, were provided frequently at locations chosen for convenience whereby the said tubing could be uncoupled. The stainless steel tubing terminated in male fittings which cooperated with mating female fittings in glass tubing, so that where desired, for example where the tubing of gas introducing means 25 actually entered the sample 20, the tubing could be and usually was glass. The mating surfaces of the said ymating fittings were essentially hemispherical in form and, when sealed with stopcock grease, were held together by friction or by double Y-clamps. When the apparatus is disassembled to clean it or to change samples, such joint is separated and, in the instance of gas introducing means 25, usually the glass tubing, only, needed washing or replacement.

'Sample receiving means 10 was a glass device made by hand for the present machine as shown in FIG. 6 and is hereinbefore described. Other vessels can be used.

Magnetic stirrer and cooperating impeller 45 were ernbodied in a Harshaw Magnastir H-60060. Cooling means 115 was a simple glass laboratory condenser (Allihn type) comprising an outer shell through which circulated water at the temperature of cold tap water (unless in individual procedures other temperatures or coolants were chosen: various cooling expedients have been used) and within this outer shell, an inner column, comprising a plurality of bulbs in series. No manufacturers mark appears on the said condenser which is approximately 101/2 inches high from the extremity of one joint of attachment in an upwards position and disposed to be the top joint, to the opposite extremity of the opposed joint and positioned to be a bottom joint. Each end of the said condenser inner column is equipped with a male hemispheric joint whereby to be attached to mating female hemispheric joints as used in the adjacent apparatus. Cooling fluid, usually water, is conducted in and out by means of rubber tubing routinely attached. Calibration means 120 was adapted from a Becton-Dickinson IO-milliliter medical glass-glass syringe, bearing no model number. Its adaptation to the instant device consisted simply in its conductive connection, by fusion of the glass formerly comprised in its male member, into an opening into the interior cavity of the instant machine. Connection made through a short length of heavy-walled rubber tube has also been satisfactory. The adaptation of the syringe also comprised the provision of screw-clamp locking means whereby the position of the plunger, once established, can be fixed rigidly.

In the machine of the instant example, heat ambient the reaction sample is usually a controlled influence upon the reaction.

Heating means 155 comprised, in the instant embodiment of the present invention, two General Electric Refiector Infrared Hea 250 watt funnel shaped electric lamps in appropriate refractory sockets, and energized through wire with heat-resistant insulation and adjustable on swivel joints as to position.

Ambient temperature sensing means 150 was, in the present embodiment, a 25 ohm platinum/nickel-constantan thermo-couple enclosed in a liquid-proof container. Temperature and temperature change control means 145 was, in the present embodiment, a Leeds and Northrup Electromax model 6201-1 temperature control, cooperating with and having internal constants adapted to 25 ohm temperature sensing means 150.

Intelligence processing means 140 in the present embodiment, was a Honeywell Brown ElectroniK model number l43X10-(PSH)-II-III-2 originally having a temperature range of 0-300 C.I and adapted for chart number 543, when used with a type I thermocouple. However, the device was modified especially for the purposes of this machine so that, responsive to being switched by timing means 70 to alternative intelligence sources, the device traces either temperature or pressure (or, in some embodiments, other influences) at positions that are usually distinguishably different on the same number 543 chart. By the choice of suitable constants in the sensing members and circuits supplying the device it is convenient to have the values of the temperature trace and of the pressure trace well enough separated on the chart that it is seldom necessary to write onto the chart as the trace is recorded, to keep record of `which trace records which information. Also, in the present machine an increase in pressure is indicated by decreasing numerical values on the chart Whereas an increase in temperature is indicated by increasing numerical values.

Timing means 70 was, in the present Emachine, a Haydon (Torrington, Conn.) model AID 225 Z-FRIC clock tlmer operating at 0.1 r.p.m. and with six timer cams on its drive shaft. The cams of timing means 70 are so positioned relatively circumferential to the shaft and to juxtaposed cam-operated switches that the several operations under control of this means occur in that time relationshrp to one another, herein before described, which renders the device operative. The timer shaft carried a marked dial.

When using relatively smaller embodiments of sample receiving means 10, the vessel confining temperature stabilizing means 35, presently a bath of mineral oil, rests by gravity upon the upper surface platform of magnetic stirring means 45. Within the said temperature stabilizing means, sample receiving means 10 is held properly positioned within the jaws of a standard laboratory clamp. The condenser here comprising cooling means is also held in position by a standard laboratory clamp. The tubing comprising a major part of the interior structure of the present device is supported upon posts standing on the particle board base or is free standing supported by its positions of attachment to the devices making up the present machine. When employing relatively large sample receiving means 10, such as means with a capacity of 500 milliliters or more, no temperature stabilizing means is commonly needed.

As a non-critical part of the present embodiment of the instant machine, not shown, but present in the device itself, there is an electronic regulator of supply voltage upon the electrical supply to all instrumentation devices. This regulator is of a standard type utilizing the constant voltage drop across a gas-discharge electronic tube as its operating and reference standard. The said regulatin-g device has a current capacity sufficient to energize all current-consuming instrument portions of the present machine. Lamps of heating means S are operated upon unregulated power line current. Temperature and temperature change control means 145 is operated from the regulated power supply. The motor driving pump means 75 is operated from unregulated power line current under control of timing means 70. Timing means 70 operates on regulated current.

While the present example specifies particular brands and model numbers of devices as employed in one actual working embodiment of the present machine, and while the employment of these brands and models was found altogether operable, other brands and models have been tested. Mention herein is not to be regarded as an endorsement or as a statement that those mentioned are the only models and makes which can be employed successfully, or that of current commercial models they are the best for the purpose. In some parts, it is believed that parts specially hand made would improve the machine.

Wherein it is stated that a device was in some way modified for the special purposes of the instant device, the modification in every case was no greater than necessary to effect the indicated modification of manner of function of the said device. In view of the statement of changed functions, the said modilications are deemed to lie routinely within the skill of those versed in the instrumentation art.

Variously about the present machine there are disposed labellel pilot signal lights, not shown in the drawings, either exposed or behind colored jewels responsively connected to certain electric circuits of the machine, by the condition of illumination of which the phase of operation of the machine can be ascertained at a glance. Such pilot lights are not critical, and if employed, may be arranged in any desired relationship to the operating cycle of the present machine to make readily available whatever indication of the machines condition of operation is deemed to be desirable. Also, presently a buzzer has been connected to sound at the termination of each 10-minutes revolution of timing means 70. It is used to alert an operator to the fact that the machine has completed one cycle. Other sounding devices such as alarm bells and the like may be connected to sound, upon the completion, by the machine, of any desired function such as a complete cycle. No alarm is needed. Further, if desired, counters to maintain numerical record of operations, and like recording devices may be built as part of or connected with the device or any of its repetitive functions, as desired.

Valve means 60 shown in FIG. l and 5 as two 3-way and one Z-way valves may be a single 4-way valve, or other group of valves so connected as to perform the function of the several valves here shown, and operated by one or a plurality of linkages such as electromotive transducers such as solenoids.

While the present machine is so devised as to have succeeding cycles initiated with reference to a time scale established by timing means 70, and recording to be made of the resulting pressures and the temperatures employed, it is entirely feasible to have the initiation of successive cycles to be under control of pressure sensing means 90 alone or in `cooperation with a pressure-change or rate-of-pressure change sensing device (not shown), or

under control of reaction temperature sensing means 30 in cooperation with a temperature change sensing device: so that, if desired, a new cycle is initiated upon the occurrence of a certain predetermined change in gas pressure or temperature change, or both, internal to the sample 20. Also, safety devices may be employed, for example reducing or interrupting applied heat or the like when such devices sense any condition which might result in danger or in serious inaccuracies. The system of the instant device wherein the initiation of successive cycles of the operation of the device is under control of a timer is deemed to be, for most purposes, a superior and preferred system, and for greatest accuracy it is usually critical.

EXAMPLE II The present example comprises two comparable parts, Part A and Part B, that are directed to two related representative operations that were carried out by the machine of Example l.

PART A Determination of the rate of thermal decomposition of Zeoxazolidinone in the absence of water It was known that the compound 2oxazolidinone, when exposed to temperatures above some unknown lower limit temperature, decomposes to liberate carbon dioxide gas, the remaining portions of the molecule apparently then combining together to produce tarry substances which cannot usually be distilled. It was desired to ascertain the temperature at which such thermal decomposition would first be perceptible and the approximate rate of such decomposition at temperatures somewhat above the initial temperature of decomposition. It was recognized that if the decomposition rate approaches zero asymptotically with temperature, the apparent limit decomposition temperature might well be fixed by sensitvity of the apparatus.

The reaction is represented, adequately for purposes of the present example, by the skeleton equation:

fCHg-CHz-NHin represents tarry substances.

It is immaterial to this invention whether the tarry substances have the suggested structure, In the instant study only the rate of evolution of carbon dioxide relative to temperature, other conditions being environmental norms, is of interest, there being no present purpose to determine other values such as a quantitative value for the factor n, or the identity and fate of hypothetical intermediates, if any.

In studying the present decomposition, if results of utmost accuracy be desired, it would seem that the entire interior contents of the machine and sample should be saturated with gas of the same identity as the evolved gas, namely carbon dioxide. This is, in general, true. However, as will appear in Part B of the present example, it is desired also to study the present reaction in the presence of a basic alkali metal compound. This compound or its decomposition products would be expected to react with consumption of carbon dioxide gas, if employed, giving rise to a source of inaccuracy of greater magnitude than any inaccuracy arising from the employment, as saturant gas, of a substance other than carbon dioxide. In this situation some error is unavoidable but it can be minimized by dilution and distribution of the evolved carbon dioxide with a moving mass of any inert gas. Therefore, to dilute evolved carbon dioxide and, by dilution and distribution uniformly throughout the machine to protect it from reaction, and in order that reactions here reported as parts A and B may be conducted under conditions as nearly identical as possible, an inert gas, presently nitrogen, is the saturant gas of choice in the present example. Any of the noble gases or a saturated hydrocarbon gas or the like could have been used.

In carrying out the determination of the present eX- ample 18 grains (0.2 mole) ofsolid 2-oxazolidinone, melting at 89 C., was placed as sample 20 in sample receiving means 10. Heating means 155 (heat lamps) were energized for a period of time to heat reaction temperature stabilizing means 35 oil bath to a temperature moderately above the melting temperature of the oxazolidinone, whereupon, in due time, the oxazolidinone liquefied. Thereupon, sample receiving means was withdrawn from the oil bath, reaction temperature sensing means 30, a thermocouple, was inserted into well 28 in the wall of sample receiving means 10 provided to receive said thermocouple, and atixed into place; gas introducing means 25 was introduced into and with its lower opening near the bottom depth of melted sample 20; sample receiving means 10 was then titted into place and attached operably into the machine by means of openable joint Valve means 60 was then so positioned as to bring gas from gas source 50 through rate-of-flow meter 55 into and through the interior of the machine and sample and out at outlet 65, such tlow being maintained until the whole interior of the said machine together with the sample were saturated with nitrogen gas. This required a few minutes.

Meantime, the temperature ambient sample 20 of temperature stabilizing bath 35 had been increased, through the operation of heating means 155, to approximately 110 C. In this condition, by-pass valve 100 was adjusted so that the flow of gas through gas introducing means continued at a slow rate and without undue disturbance of the sample, as it bubbled through. Also the response of pressure sensing means 90 was ascertained by operation of calibration means 120. The resulting trace upon the chart made by intelligence processing means 140 was noted. The entire device was then assembled and all parts connected for subsequent automatic operation as described hereinbefore. Such operation was then begun.

In such automatic operation, all timed operations were under control of timing means 70. Valve means 60 was so positioned as to flush the interior of the machine with nitrogen for a rst temperature sensing minute. Valve means 60 was then operated by timing means 70 to close the interior contents of the entire machine against ingress or egress of contents including gaseous contents. Temperature ambient sample 20 was maintained constant at 110 C. for a 3-minute stabilization period, as pump means 75 circulated the nitrogen gas at essentially the same rate as the tlush, together with evolved carbon dioxide if any, within the closed system of the ARRA. During this stabilization period, processing means 140 continued to record temperature of the sample. At the conclusion of the 3-minute stabilization period intelligence processing means 140 was connected by timing means 70 to pressure sensing means 90, and a one minute graphic record was made of the pressure of the interior of the device.

During the time that the interior contents of the machine system was closed by the operation of valve means 60, gas from gas source 50 passed through rate-of-ow meter 55 and was conducted to waste. If the employed gas were very expensive or if other persuasive reasons had existed, this gas flow could be stopped when not in use in ushing and filling the machine; however, it has been deemed less costly and more readily conducive to accurate results to waste the relatively small amount of gas which is vented away during the reaction cycles than to operate to save it with the concomitant necessity for checking and perhaps recalibrating the rate-of-ow of gas each time.

At the conclusion of the pressure sensing minute, intelligence processing means 140 was again connected by timing means 70 to reaction temperature sensing means 30 and temperature of reacting sample 20 was sensed and charted as it was further automatically maintained constant at the level for a period of three minutes. In this way, a graphic intelligence record was made, indicating the said reaction temperature over the said interval of time.

At the conclusion of the said three-minute reaction interval during which temperature record was taken, intelligence processing means was disconnected from reaction temperature sensing means 30 and immediately again connected for one minute to pressure sensing means 90, all connection changes being controlled by timing means 70, while temperature and temperature change control means cooperating with heating means 155 and ambient temperature sensing means continued to maintain the temperature in reaction temperature stabilizing means 35 constant at the said 110 level. During the succeeding minute, a graphic record was made on the chart of intelligence processing means 140 indicating the pressure of the interior of the machine. It will at once be evident that the record thus obtained corresponds to and exemplifies the four tem sense sequence hereinbefore described. At the end of the second pressure sense time, intelligence processing means 140 was caused to record sample temperature, while valve means 60 was operated to supply a flush of inowing gas from gas source 50 via gas inlet 5 through the entire machine, and thereafter to outlet 65; temperature and temperature change control means 145 of which the temperature increment controls were, in this instance, under control of a human operator, caused the operation of heating means lamps whereby to raise the temperature ambient sample 20 from 110 degrees C. to the next temperature higher at which a determination was desired. The temperature interval is, of course, susceptible of adjustment in increments of any desired magnitude. In the instant operation, the determination of any inflection position of the decomposition curve within about ten degrees being deemed adequate, ten degree temperature increments were used. Thus, during the next succeeding two minutes, there was brought about a gas flush and a ten degree increase in the temperature of the reaction temperature stabilizing means bath 35 and therewith of sample 20. When the said new temperature was sensed by ambient temperature sensing means 150 cooperating with temperature and ternperature change control means 145, the lamps of heating means 155 were further operated only intermittently to maintain the said temperature.

Thus, at the conclusion of a two minute interval succeeding the last pressure sensing minute, there had occurred a two minute flush of the entire interior contents of the system with nitrogen and a temperature increase of ten degrees C., to a new sample ambient reaction temperature of 120 C. Thereupon, further under control of timing means 70, valve means 60 operated to discharge gas from gas source 50 via outlet 65, while closing the interior of the machine as a closed, circuitous system; and the maintenance of sample 20 at the new temperature went forward for a total period of ten minutes further of graphic record comprising a first unit of four minutes, one of flush and three closed, with temperature recording, whereby to stabilize the interior of the ARRA system under the new conditions.

At the conclusion of the three minute stabilization time, intelligence processing means 140 was again caused by timing means 70 to record, for the duration of one minute, a trace related to the coordinates of the employed chart, representing interior pressure of the machine as sensed by pressure sensing means 90. At the conclusion of the one minute trace of pressure as sensed by pressure sensing means 90, intelligence processing means 140 was caused to cease recording a pressure trace, and connected instead to reaction temperature sensing means 30 and caused to make a 3-minute record of temperature as sensed thereby.

At the conclusion of the 3-rninute temperature sense and reaction time, intelligence processing means 140 was caused by timing means 70 to discontinue recording temperature trace from reaction temperature sensing means 30 and caused instead to record for one minute a trace representing pressure as sensed bypressure sensing means 90, the recording of such pressure trace, and all the aforesaid changes in operating conditions interior to the said machine being under control of timing means 70. Valve means 60 was then operated to cause gas from gas source 50 to flow through and flush the ARRA interior and thence to waste via outlet 65; temperature and temperature change control means 145 cooperating with ambient temperature sensing means 150 initiated another ten degrees C. rise in temperature, stabilizing at 130 C.

In this manner, the device continued cyclic operation as described, consisting of a recurring sequence of ten degree temperature rises accompanied in each instance by a one minute flush of the gaseous interior contents of the system, with a three minute stabilizing cycle, a one minute pressure sense, a three minute temperature Sense, a further one minute pressure sense. The resulting data as recorded on the chart tended to be self-validating in that, since no appreciable decomposition of the oxazolidinone sample 20 took place below 190 C., the record points indicating pressure as recorded up to the initial decomposition ternperature lay in virtually a Straight line, ascending very slowly, corresponding to the background surface or wall reaction rate of the oxazolidinone decomposition.

The ten minute cycle at 198 C. (manually controlled and intended to be 200 C.) indicated a distinct rise in decomposition rate. A ten minute cycle at 210 C. indicated decomposition at a rate about times that at 198 C.

Each of the said cycles of the ARRA required minutes for completion. The decomposition of 2-oxazolidinone was scanned in 10 cycles over the temperature range from 110 to 210 C. Temperature settings were manually controlled. T-he entire determination took about 1an hour and 40 minutes. It was ascertained that, in practical terms, thermal decomposition of the 2-oxazolidinone at a significant rate under the said conditions begins at a temperature above 190 and below 200, nearer 200 C. Rates of decomposition at these temperatures were also ascertained.

PART B Study of the rate of decomposition of 2-oxazolidinone in the presence of a small amount of the 3-so'dium derivative of 2-oxazolidinone In this second part of the present example, the procedures followed were essentially identical with those in the foregoing part A except that the sample 10 consisted essentially of 18 grams (0.20 mole) of 2-oxazolidinone from the same preparation batch as the foregoing, and in addition 0.5 gram (0.004 mole) of the 3-sodium salt of 2-oxazolidinone. The sample had a diffuse melting temperature of approximately 100 C.

Further, the temperature interval, approximately evenly 10 in the foregoing part was varied under control of a human operator between determinations in the instant part.

At its melting temperature of 100, the sample underwent wirtually no decomposition. However, by the time it had been heated to 109, appreciable decomposition during 10 minutes was noted. At 125 C. the decomposition was at a rate about three times that at 109 C. Further increases in the rate of decomposition were noted, successively, at the employed temperatures of 129 C., 138 C., 144 C., and 155 C. The decomposition rate at 155 C. was :about ten times as great as at 109 C. and was calculated at about 2.73 10*5 moles per mole per second, under the stated conditions. The apparatus readily measured a decomposition at a rate of 2.26 106 moles per mole per second.

32 EXAMPLE nr A reaction rate determinator machine of the present invention is assembled on the same mechanical supports and with many of the same parts as the machine of 'EX- amples I and II; the machine of the present example differs from the former machine as follows:

Reaction temperature stabilizing means 35, exemplified in Example 1 as an oil bath, is eliminated and ambient temperature sensing means 150 is eliminated: reaction temperature sensing means 30 is connected both to intelligence processing means 140 and to temperature and temperature change control means 145. Sample receiving means 10 is, in the present example, a vessel essentially as described hereinbefore, but constructed of fused quartz, because of its tranSparency to certain actinic radiations. It is carefully made to preserve optical transparency. Sample receiving means 10, together with reaction temperature sensing means 30, the electrical leads to the said temperature sensing means, and the connection with gas introducing means 25, manifold and associated structures of the present machine are enclosed by wrapping in lead alloy foil which is caused to conform closely with the exterior form of those portions of the machine thus wrapped. The lead alloy foil (not shown) is cut through in a pattern corresponding to three sides of a rectangle, and the rectangular flap thus formed is folded along a line corresponding to the fourth side of the said rectangle to define an aperture through said foil whereby radiation incident upon the exterior of sample receiving means 10 is admitted to the interior thereof to fall upon sample 20. The position of the said aperture is so chosen with respect to radiation means 200 that such radiation will not be intercepted in any appreciable ldegree by reaction temperature sensing means 30 but may fall directly upon sample 20.

A source 200 of such radiation as is to be studied to ascertain whether it will induce, or modify, the rate, or course of, chemical reaction is provided adjacent the said aperture land so disposed so as to introduce said radiation to sample 20; in the present example, the said radiation source is a mercury vapor lamp of which the emitted radiation is relatively rich in ultra-violet of a wavelength between about two thousand :and thirty-nine hundred angstrom units. A housing disposed about the lamp permits radiation to escape through a shutter structure so disposed that the quantity of radiation incident upon sample 20 can readily be controlled.

-Adjacent said aperture in the lead foil cover over sample receiving means 10 and associated structures, there is diS- posed radiation sensing means 205, presently a photoelectric cell provided with a mask (not shown) and carefully positioned so that the said cell intercepts radiation of the same quality as, and in a fixed quantitative ratio to, the radiation intercepted by sample 20. The output of the said cell, suitably amplified, is conveyed to intelligence processing means and there translated and graphically recorded on suitable charts.

The sensing and recording of conditions ambient the reaction of sample 20 are modified to provide for the periodic recording, in fixed time relationship, of intelligence representing the intensity of imposed actinic radiation. In particular, the electrical switch connections, presently under cam control in timing means 70 are changed, employing switches and cams hitherto idle, so as to interrupt the 3-minute temperature items hereinbefore described and to provide for an information sequence as illustrated in FIG. 4, differing in that, presently, actinic radiation, not magnetic linx, is recorded.

It should be understood that the foregoing examples represent only certain possible embodiments. Alternative intelligence processing means 140 has been a standard laboratory l0-point recorder, such as a Brown ElectroniK, Minneapolis Honeywell Model 153X64 PF-X4l, so connected that the graphic line traced by each of a selected