RESEARCHES UPON RESPIRATION, MADE IN THE PHYSIOLOGICAL LABORATORY OF JEFFERSON MEDICAL COLLEGE. -BY- HENRY C. CHAPMAN, M, D. AND ALBERT P. BRUBAKER, M, D. No. 1. ON THE CONSUMPTION OF OXYGEN AND THE PRODUCTION OF CARBON DIOXIDE IN ANIMALS. From the Proceedings of the Academy of Natural Sciences, Philadelphia, fanuary, 1891. 1891.] NATURAL SCIENCES OF PHILADELPHIA 13 RESEARCHES UPON RESPIRATION, HENRY C. CHAPMAN, M. D. AND ALBERT P. BRUBAKER, M. D. No. 1. On the Consumption of Oxygen and the Production of Carbon Dioxide in Animals. Of all subjects of biological enquiry there is none, perhaps, that has attracted more attention or exceeds in importance that of the accurate determination of the consumption of oxygen and production of carbon dioxide and water in man and animals. Not only is the proper ventilation of our dwellings, lecture rooms, theatres, halls of justice, based upon such knowledge but all estimates as to the amount of radiant energy set free through the combustion of food, as determined by calorimetrical experiments, are dependent upon the same. Passing over the early observations of Boyle, Hales, Cigna, Black and Priestley which showed that the air becomes so materi- ally modified by animals breathing it as to soon render it irrespira- ble unless renewed, it may be said that Lavoisier, by his classical re- searches, first established (1785) the modern theory of respiration and calorification, namely, that the carbon dioxide and water pro- duced during respiration and the heat thereby set free are due to the oxidation of the carbon and hydrogen of the food. While subse- quent investigations, such as those of Allen and Pepys, Milne Ed- wards, Despretz, Dulong, Valentin and Brunner, Boussingault and Barral, confirmed in the main the profound views announced by Lavoisier, nevertheless the differences in the results obtained were such as to induce Regnault and Reiset1 to undertake an extended series of researches upon the respiration of different animals, more particularly with the view of determining the amount of oxygen con- sumed and carbon dioxide produced. The results of this elaborate investigation, it may be added, have never, in the main, been questioned. Inasmuch, however, as the water exhaled by an animal is not determined by the Regnault-Reiset apparatus, and in so far as known to the authors they are the only experimenters who have ever had the opportunity of comparing the amount of oxygen con- 1 Recherches Chimiques sur la Respiration des animaux des diverscs classes. Par MM. V. Regnault et J. Reiset, Annales de Chimie et de Physique, 3me Ser., tome XXVI, 1849. 14 PROCEEDINGS OE THE ACADEMY OF [1891. sumed as so determined directly, with the amour t absorbed as deter- mined indirectly from the carbon dioxide and water produced, as obtained by means of a Voit respiration apparatus, it does not appear superfluous to submit the results of experimenting with the two kinds of respiration apparatus.1 Description of Apparatus. The Regnault-Reiset respiration apparatus in the fulfilment of the physical and chemical requirements incidental to the construc- tion of such apparatus, remains to this day unsurpassed. It consists essentially of the following three parts : A central glass bell-jar or chamber for the reception of the ani- mal, communicates on the one side with two glass pipettes contain- ing an alkaline solution for the absorption of the carbon dioxide produced by the animal, and on the other side with a glass pipette filled with oxygen to replace that absorbed by the animal in the bell-jar. The central glass bell-jar or chamber A, Pl. I, tubulated above and having a capacity of about 47.6 litres,2 is cemented through its lower open portion into the inner of two grooves with which the iron-plate upon which it rests is provided. The metal plate itself presents a central opening sufficiently large for the introduction of the animal into the chamber and is hermetically closed (the animal having been introduced) by means of a circular-metal lid, the latter being tightly screwed up to the under surface of the plate by means of bolts. The inner circular portion of the metal plate and upper surface of the metal lid closing the inferior opening of the central bell-jar are painted with red lead so as to avoid any ab- sorption of oxygen through oxidation of the metal. In order that the animal should not stand directly on the circular metal disk clos- ing the inferior opening of the central bell-jar (which would cool it too much) a movable bottom consisting of a circular wooden disk pierced with holes upon which the animal is placed is passed up 1 The results obtained by Voit's respiration apparrtus will be presented in a subsequent communication. 2 The absolute capacity of the jar or that of the tubes connecting it with the pipettes need not be determined since the investigation, is based upon a comparison of the composition of a given amount of the air within the jar at the beginning and at the end of the experiment and any extra amount of air within the jar as well as that in the connecting tubes can be neglected, as they are on both sides of the equation. 1891.] NATURAL SCIENCES OF PHILADELPHIA. 15 through the inferior opening of the bell-jar. This can be easily done as the wooden disk is somewhat smaller than the inferior opening of the jar. The circular wooden disk with the animal placed upon it, after being introduced through the inferior opening of the chamber is, slightly rotated and then lowered and comes to rest upon three pivots projecting inwardly over which the disk glides, it being sufficiently notched upon its sides for that purpose. If it be desired to preserve the urine and feces this can be accomplished by placing a circular metal pan within the space between the under surface of the wooden disk and upper surface of the iron lid clos- ing the inferior opening of the jar into which space the excreta would otherwise fall. The central glass bell-jar or chamber, A Pl. I, with a thermometer suspended within it and containing the ani- mal resting upon the wooden disk, the inferior opening of the jar being closed by the iron lid, is surrounded by water, the latter being held by four rectangular glass plates fitting into the outer of the two grooves with which the iron plate is provided. As it is essential that the temperature of the central bell-jar contain- ing the animal should be maintained as constant as possible, that of the water surrounding it must be maintained equally so. Through the upper superior portion of the central bell-jar, A Pl. I, pass four tubes L M N O. Through the tube L the jar commun- icates directly with the flask P containing a solution of soda or pot- ash and indirectly with the pipette F containing the oxygen to be respired. By means of the tube M and the small mercurial manome- ter connected with it the pressure of the gas within the jar A can be determined from moment to moment. Through the two connecting tubes N O the jar A communicates with the two pipettes R S con- taining the alkaline solution for the absorption of the carbon diox- ide. The accessory tube T given off from the main tube O and leading to the large mercurial manometer enables us, as we shall see presently, to draw out of the jar A a sample of gas for analysis. The iron plate with the bell-jar A is firmly supported by a heavy frame-work resting upon the floor. The two glass pipettes, Pl. I, R S, serving for the absorption of the carbon dioxide, connected through their lower extremities by an india-rubber tube and having a capacity of about three litres, are filled with a solution of caustic soda or potash whose weight and composition have been previously determined. The two glass pipettes R S are firmly attached to two metal supports. The supports are suspended by chains from the 16 PROCEEDINGS OF THE ACADEMY OF [1891. beam V and with the movement of the latter alternately ascends and descends uniformly in a vertical manner the supports moving in a frame. The beam V is moved by the eccentric X which in turn is moved by the rotation of a number of interlocking toothed wheels W the movement of the latter being due to the fallof 150 kilogrammes, through 10 metres and regulated by a fan. The relations of the wheels, weight, etc. are such as to necessitate the winding up of the weight once only in fifteen hours. The vertical movement of the pipettes just described is such that as the pipette R, for example, ascends, the solution of soda within it passes into the pipette S which descends; the air in the latter freed of its carbon dioxide passing into the jar A while the air of A loaded with carbon dioxide passes into the pipette R. On the other hand, as the pipette S ascends and R descends, the solution of soda passing from S to R, the air of the pipette R, freed of its carbon-dioxide, passes back to the jar A and the air of the latter, loaded with carbon dioxide, passes into the pipette S. In order that the absorption of the carbon dioxide by the soda be as thorough has possible a number of glass tubes, open at both ends, are placed within the pipettes, the walls of these tubes remaining moistened with soda when the pipettes have emptied themselves of the alkaline solution. They present consequently a large absorbing surface. It will be observed that as the pipette S takes air from the upper portion of the jar A and the pipette R from the lower portion, the play of the pipettes not only ensures the absorption of the carbon-dioxide in proportion as it is produced by the animal but keeps up a continual agitation of the air within the jar A which tends to maintain its composition uniform. The frames in which the glass pipettes move, together with the wheels etc. moving them, are firmly supported by a heavy metal frame- work resting upon the floor. The pipette,1 F Pl. I, filled with oxy- gen by means of the tube d, replacing that of the jar A absorbed by the animal, has a capacity of 19,440 c.c. between the marks b and cand it communicates through its upper opening and with the flask P which in turn communicates with the jar A and, through its lower opening with a vessel e which receives the liquid that flows out of the pipette 1 In the original experiments as performed by Regnault and Reiset three oxygen pipettes similar to the one described above were successively used, the ex- periment lasting until the last pipette was exhausted. It was found, however, by the authors, though provided with the three pipettes, that it was easier on account of the connections to refill the same pipette when necessary than to substitute for it a second pipette previously filled. 1891.] NATURAL SCIENCES OF PHILADELPHIA. 17 F, when the latter is filled with oxygen, and with the tube/into which the liquid flows that drives the oxygen out of the pipette over into the jar A. The oxygen made use of by the authors was obtained by heating in an iron retort a mixture of chlorate of potassium and black oxide of manganese and passing the gas so developed through a solution of caustic potassa. The gas so purified and further tested by explosion with hydrogen, appeared to be pure. In order to intro- duce the oxygen into the pipette previously filled with a concen- trated solution of calcium chloride, little or no oxygen being ab- sorbed by that liquid, the stop cock on the upper tube d putting the oxygen reservoir in communication with the pipette and that on the inferior tube J conducting the fluid away, must be opened, and as the oxygen passes into the pipette the solution of the calcium chloride flows out into the vessel e. The pipette should be filled under a little higher pressure than that of the atmosphere and the gas allowed to acquire the same temperature as that of the latter. By allowing a little oxygen to escape and so making its elastic force equal to that of the atmosphere, the level of the solution of calcium chloride can be brought to that of the lower mark c. The height of the barometer and the temperature of the oxygen must now be noted, the latter being ascertained by means of a thermom- eter suspended within the pipette. After this somewhat detailed description of our respiration ap- paratus let us endeavor to describe the manner of conducting the experiments. Method of Experimentation. The oxygen pipette being filled under the atmospheric pressure H and a temperature t let V represent the capacity in litres of the pipette between the upper and lower marks and / the pressure of the aqueous vapor abandoned to the oxygen by the solution of cal- cium chloride, then the weight W of the oxygen delivered to the bell-jar supposing the pipette to be emptied to the lower mark,1 will be given by the equation 1 In order to be able, if necessary, to stop the experiment at any moment the pipette was graduated in litres and demilitres Owing, however, to the uncer- tainty as to the accuracy of the graduation incidental to the globular form and large size of the pipette it is undesirable to terminate the experiment before the pipette has emptied itself to the upper mark. 18 PROCEEDINGS OF THE ACADEMY OF [1891. 1 H- f W=T4298 V . X 1 + 0-00367 t 760 The pressure of the vapor from the calcium chloride solution to be deducted from the barometric pressure, was accepted by the au- thors as being from 0'47 to 0'55 of the pressure of aqueous vapor at corresponding temperatures according as the temperatures of the oxygen varied from 16° C to 21° C, the experiments being made in winter or summer. The pipettes for absorbing the carbon dioxide are now weighed and then filled with a solution of caustic potash or soda and then again weighed, the difference giving the weight of the solution, the amount of carbon dioxide present in the soda having been previously determined by analysis, the method of which will be described pres- ently. The animal is now introduced, with food and drink if necessary, into the bell-jar, the walls of which have been previously moistened. In order to maintain the temperature of the water sur- rounding the bell-jar as constantas possible, the experiment should begin with the temperature of the water a little higher than that of the surrounding atmosphere, the heat given off by the animal compen- sating for that given off by the water. The lid closing the inferior opening of the jar is now screwed up and the two-way stop cocks so turned that the interior of the bell-jar is put in communication with the interior of the oxygen pipette through the intermediation of the flask P but cut off from the atmosphere, and the carbon dioxide pip- ettes put in motion through the descent of the weight. Let us suppose that the respiration of the animal consists simply in the con- sumption of oxygen and production of carbon dioxide. It is evident that in proportion as the oxygen of the chamber is consumed by the animal and the carbon dioxide produced is absorbed by the soda of the pipettes, the elastic force of the gas within the chamber is di- minished and, if the chamber communicates with the oxygen pip- ette, the oxygen absorbed will be at once replaced by an equivalent amount of oxygen, provided that the solution of calcium chloride be added through the tube/to that in the oxygen pipette in quantity sufficient to maintain the elastic force of the gas equal to that of the 1 The number l'4298=weight of 1 litre of oxygen at standard pressure and temperature. 0 00367=coefficient of expansion for each deg. C. 76O.=standard barometric pressure in millimetres of mer- cury. 1891.] NATURAL SCIENCES OF PHILADELPHIA. 19 atmosphere. This successive addition of the solution of calcium chloride is accomplished by putting the tube of the oxygen pip- ette in communication with the reservoir G containing a con- centrated solution of calcium chloride, the level of which is main- tained very nearly constant by means of the three glass flasks 1, 2, 3 filled with the same solution and which empty themselves success- ively as the level of the fluid in the reservoir falls, the flasks differing slightly from each other in the length of their necks. In proportion as the oxygen in the pipette becomes rarefied the liquid column in the tube falls and the elastic force of the air in the tube diminishes, the consequence of which is that the solution of calcium chloride flows from the reservoir into the tube and thence into the pipette. Never- theless the elastic force in the chamber does not remain constant during the time that the pipette furnishes oxygen. It diminishes in proportion as the pipette becomes filled with the solution of calcium chloride, that is if such solution was at the same level in the tube and the pipette at the moment that the former was cemented to the tube leading from the reservoir, the pressure of the air within opposing the flow from the reservoir1. As a matter of fact, however, the vari- ations due to the cause just mentioned may be restricted to very narrow limits by simply raising the level of the solution in the tube a few inches higher than that of the solution in the pipette before joining the tube to that leading from the reservoir. By so do- ing an excess of pressure of the gas within the chamber of about 1 centimeter is maintained which is of advantage in compensating for the small amount of carbon dioxide 1 to 2 per cent always present in the chamber notwithstanding the constant play of the pipettes for the absorption of the latter. It should be mentioned, however, in this connection that absolute constancy of pressure can not be main- tained since variations in barometric pressure modify that of the gas within the chamber. Towards the end of the experiment, when there only remains about 300 cubic centimeters of oxygen in the pip- ette, the tubes are disconnected and the solution of calcium chloride poured into the tube until the solution in the pipette rises to the level of the upper mark when the stop cock on the tube is turned off. By this time there is an excess of pressure within the chamber of about 2 to 3 per cent and while the oxygen corresponding to this ex- 1 That such is the case is shown by disconnecting the tubes for a moment after the flow from the reservoir has ceased, for in connecting them again the flow at once begins. 20 PROCEEDINGS OF THE ACADEMY OF [1891. cess is consumed by the animal, plenty of time is afforded for making the temperature of the water and therefore of the chamber the same as at the beginning. By observing the fall of the mercury in the gauge the requisite number of millimetres of mercury is obtained which, if added to or subtracted from the observed barometric pres- sure, makes the final equal to the initial pressure.1 During this time also a sample of the gas of the chamber is drawn off for analysis. In order to draw off a sample of gas from the chamber for analy- sis the tube already referred to as being given off from the tube T is put in communication with the large mercurial manometer. In this case as the mercury flows out the gas flows into the manometer whence, as will be presently described, it is transferred for analysis to the Hempel burettes. It is indispensable that the sample of gas should be drawn from the chamber as the pipette R ascends, inas- much as at that moment the gas of the chamber loaded with carbon di- oxide passes into that pipette and consequently into the manometer. If the sample was drawn as the pipette descends, the gas so obtained being freed of its carbon dioxide would not represent the composition of the gas within the chamber. The sample of gas having been drawn from the chamber at the moment that the pressure of the gas was the same as at the beginning of experiment the movement of the pipettes for the absorption of the carbon dioxide is stopped. The animal is removed and weighed together with food and excreta and the pipettes at once also weighed. The increase in weight of the pipettes at the end of the experiment as compared with their weight at the beginning represents both the carbon dioxide absorbed and the hygrometric water fixed by the concentrated solution of soda. The weight of the carbon dioxide contained in the solution of soda is then determined by analysis and deducting therefrom the the weight of the carbon dioxide that the solution contained at the beginning of the experiment as previously determined, the difference will be the weight of the carbon dioxide absorbed during the experi- ment by the solution of soda. This weight added to that of the car- bon dioxide remaining in the chamber at the end of the experi- ment as determined by analysis of the sample drawn from the cham- 1 If for Convenience it he necessary to terminate an experiment at any mo- ment, and a difference still exists between the final and initial temperatures, and between the final and initial pressures, the error so arising, due to the initial vol- ume of the gas of the chamber being thereby increased or diminished, must be taken into consideration in the summing up of the general results. 1891.] NATURAL SCIENCES OF PHILADELPHIA. 21 ber will give the total weight of the carbon dioxide produced by the animal. It is evident if during the experiment, oxygen has only been consumed and carbon dioxide only produced, the latter being as rapidly absorbed as produced, that the composition of the gas of the chamber will be the same at the end as at the beginning of the ex- periment. That the gas of the chamber during the experiment does not differ to any great extent from that of the atmosphere is shown not only by the analysis of the air but from the fact that the ani- mals do not experience any discomfort even after a much longer so- journ in the chamber than that to which they were subjected in the experiments by the authors. It should be added in this connection that the air of the chamber is neither altered by the food nor ex- creta of the animal. Let us consider now the data at our disposal by means of which the composition of the air of the chamber at the beginning and end of the experiment can be determined. The vol- ume of air at the beginning of the experiment is equal to that which is contained in the chamber, in the pipettes for the absorbing of the carbon dioxide, and in the connecting tubes less the volume of air displaced by the animal and food which are introduced into the the chamber. The determination of both the latter volumes when the density of the food can not be determined, can only be made ap- proximately but in taking it as equal to the volume of air displaced by an equal weight of water the error committed can be but slight. This is equally true at the end of the experiment, for apart from the oxygen consumed and carbon dioxide produced and nitrogen present being in relatively large quantities it must be remembered that by far the greatest part of the food consumed is still present either within the animal or in its excreta. Indeed the only part of the food actually disappearing and which diminishes its volume is that entering into the formation of the carbon dioxide and which must in any case occupy less volume than the water having the same weight as the carbon dioxide produced. Let V represent the volume in li- tres of the air of the chamber on the supposition that the animal has just been enclosed within the latter, H the elastic force of that air, at its temperature, f the pressure of the aqueous vapor at that tem- perature to be deducted from H, it acting in opposition to it, then the weight of the oxygen and nitrogen that the chamber contains at the beginning of the experiment can be determined by substituting in the following equations 22 PROCEEDINGS OF THE ACADEMY OF [1891. 1 H-f Weight of oxygen-0'2095. lgr-, 4298. V. . l-f-0-00367.t 760 1 H-f Weight of nitrogen=0'7905. lgr-, 2562. V. . l+0-00367.t 760 the values of V, H, t and f obtained by observation ; 0'2095 and 0'7905 representing the amounts of oxygen and nitrogen per volume in 100 volumes of air and l,gr'4298 and l'gr-2562 the weight of a li- tre of oxygen and nitrogen respectively at standard pressure and tem- perature. At the end of the experiment H, t and f being made the same as at the beginning, the total volume of air then within the chamber will be unchanged its composition having been modified by the amount of carbon dioxide or other gases produced and remain- ing in the chamber. The weight of carbon dioxide oxygen and ni- trogen or other gases present in the chamber at the end of the ex- periment is then determined by multiplying the weight of the gases obtained from the sample of gas drawn from the chamber by the ra- tio of the volume of air of the chamber V to that of the sample v. Let us suppose that C, O and N represent the weight of the carbon dioxide oxygen and nitrogen in the sample of air drawn from the chamber and that^=M; then CM, OM and NM will be the weight of the carbon dioxide, oxygen and nitrogen in the chamber at the end of the experiment. The weight of the carbon dioxide present in the chamber must be added as already mentioned to that obtained from the pipettes to obtain the total amount of carbon dioxide produced while the weight of the oxygen remaining in the chamber must be de- ducted from the sum of the weight of oxygen present in the cham- ber at the beginning of the experiment and that delivered to the chamber during the experiment to obtain the total weight of oxygen consumed. Finally the increase or diminution in the weight of the nitrogen within the chamber at the beginning and end of the experi- ment amounting to perhaps the 0'02 of a gramm the authors regard as being due to errors in the eudiometrical readings rather than as nitrogen exhaled or inhaled by the animal, the amount of nitrogen in the chamber present being the same at the end as at the beginning of the experiments. Method of Determining the Weight of the Carbon Dioxide Absorbed by the Solution of Soda in the Pipettes. The method made use of by the authors in determining the weight of the carbon dioxide absorbed by the soda solution in the pipettes 1891.] NATURAL SCIENCES OF PHILADELPHIA. 23 was essentially that recommended by Regnault. It depends upon the decomposition of the sodium carbonate in the solution through the addition of sulphuric acid and the reabsorbing of the carbon di- oxide so set free by passing the latter through bulbs, etc. containing soda, the increase in the weight of the bulbs giving the weight of the carbon dioxide absorbed. The apparatus represented in F Plate II consists of a litre flask B into which is poured a sample of the soda solution from the pipettes to be analyzed. Through the cork closing the flask pass three tubes, the first tube communicates with the U shaped tube A containing soda and pumice stone for the ab- sorption of the carbon dioxide in the air that passes through the ap- paratus at the end of the experiment. The second tube serves for the introduction of the sulphuric acid which should be a little less dense than the alkaline solution and added gradually to the latter, the mixture being slowly heated by gas jets to boiling. The third tube communicates with the narrow flask C containing concentrated sul- phuric acid, the latter communicating in turn with the tube D containing pumice stone and sulphuric acid for drying the air and through which the carbon dioxide developed passes on its way to the Liebig bulbs E containing a concentrated solution of soda and the tube F containing pumice stone and small pieces of caustic soda. The remaining tubes G and H contain pumice stone and concentrated sulphuric acid. The increase in weight of the three tubes E F and G at the end of the experiment, the tubes having been previously weighed at the beginning, gives the weight of the carbon dioxide absorbed. To ensure accuracy in the weighing of the tubes E, F, G three similar tubes disposed in the same manner and displacing an equal volume of air should be used as counter weights. The tube H containing pumice stone and sulphuric acid serves to prevent the moist air depositing water in the tube G. Finally by means of the aspirating jar I a current of air is made to pass through the apparatus and of so carrying the last traces of carbon dioxide to the soda solution absorbing it. In order to maintain the tubes firmly bound together and to facilitate their connection and disconnection they are all clamped to a solid wooden frame- work by means of w'hich they can all be removed together and in position when desirable. The weight of the carbon dioxide pre- viously existing in the soda solution placed in the pipettes at the beginning of the experiment for absorption of the carbon dioxide 24 PROCEEDINGS OF THE ACADEMY OF [1891. produced by the animal is determined by means of the same appara- tus and must of course be deducted from the weight of the carbon dioxide absorbed, present in the soda solution at the end of the ex- periment. It has already been mentioned, that by means of the accessory tube T Pl. I given off by the tube leading from the chamber, to the carbon dioxide pipette R, that a sample of gas can be drawn into the large mercurial manometer. By so turning its three-way stop cock, as to let the mercury flow out, the sample so obtained is after- wards driven over to the absorbing or explosion apparatus for anal- ysis. This is accomplished by pouring mercury into the limb of the manometer opposite that containing the sample, the three-way stop cock being so turned as to put both limbs in communication and then of retransferring to the manometer for determination of volume of gases absorbed. The method made use of by the authors, however, in order to expedite the analysis is to draw the sample of gas from the chamber directly into a Hempel graduated burette B1 filled with mercury, the latter, Plate III, Fig. 1, flowing out of the burette as the mercurial reservoir A with which the burette com- municates is lowered by means of the wheel work C attached to the solid wooden frame fastened to the table. The sample of gas so ob- tained reduced to standard temperature and pressure is then driven out of the burette B by elevating the mercurial reservoir into a Hempel pipettte F containing a concentrated solution of soda and after remaining there long enough for the absorption of any carbon dioxide present is driven back into the graduated burette by lower- ing the mercurial reservoir, the diminution in volume, the latter re- duced to standard temperature and pressure, representing the carbon dioxide absorbed. The pipette for the absorption of the carbon diox- ide being removed, the burette is connected with one containing pyro- gallic acid into which the sample of gas just freed of its carbon diox- ide is driven by elevating the reservoir and in which it is allowed to remain until the oxygen present is absorbed. The sample of gas being then driven back into the graduated burette by lowering the reservoir the diminution in volume, reduced to standard temperature and pressure, represents the volume of oxygen absorbed. The volume of gas now remaining in the burette the authors regarded as consist- ing of nitrogen. At least the volume of residual gas'in the burette was 1 Neue Methoden fur Analyse der Gase, von Dr. W. Hempel, Braun- schweig, 1880. NATURAL SCIENCES OF PHILADELPHIA. 1891.] 25 usually such as it ought to be on the supposition that it was nitrogen, and as can be shown experimentally by transferring the gas to the Explosion Apparatus Plate III, Fig. 2. The connection with the burette containing the gas is made with that limb of the apparatus A which has been previously filled with a solution of soda the latter being forced up by the mouth applied at the end of the other limb F and the latter then clamped. A known volume of oxygen being then introduced, and a sufficient volume of detonating gas developed elec- trolytically by means of three Daniell cells connected with the plati- num plates, through the'binding screws H H the gaseous mixture is exploded by connecting a Ruhmkorff apparatus with the platinum terminals G G. The fact of there being no diminution in the volume of the residual air as ascertained by transferring the gas back to the graduated burette proves the absence of at least hydrogen, heavy car- buretted hydrogen, C2 H4 and light carburetted hydrogen or marsh gas, C H4 the gases which are the most likely to be present, the two former coming from the rectum of the animal the latter from its food. That there is no free hydrogen1 is further shown in the absence of absorption on passing the residual gas through palladium. The following tabulated actual experiment will serve to illustrate the gen- eral method and order of experimentation. Experiment No. 17. Oct. 29th, 8.45 P. M. 2 Pigeons. BEGINNING OF EXPERIMENT. Weight of animal . 0,kil-567 " " food O'kn 000 Barometer ......... 748mm' Temp, of Chamber 18 °C Pressure of Aq. Vap 15°'35 Vol. of Gas of Chamber lit. 748-15'35 lit. at standard temp. = 47'6-0'567. = 42'53 and pressure 760 (l-|-00367T8) 1 Were these gases present in the residual air then after explosion with oxygen water and carbon dioxide would be formed and retained in the pipette the volume of the gas being consequently diminished. It should be mentioned, how- ever, in this connection that it is extremely difficult whatever the kind of apparatus used, to determine such very small volumes of hydrogen or carburetted hydrogen or marsh gas as are likely to be present in the sample of gas drawn from the cham- ber for analysis and in neglecting to take these gases into account no very sensible error, at least in most instances, will be introduced into the result. 26 PROCEEDINGS OF THE ACADEMY OF [1891. GRAMMES. Weight of Oxygen in = 0'2095 1'4298 gr. 42 53 = 12739 Chamber. Weight of Nitrogen in = 07905 1'2562 gr. 42'53 = 42'220 Chamber Temp, of Oxygen in Pipette 19° Pressure of Aq. Vap. aband. by Calcium Chloride sol. . 7'mm'679 GRAMMES. Weight of 748-7-67 Oxygen in = 1'4298 gr. 19'440 = 25'297 Pipette. . 760 (1+00367'19) Weight of Pipettes and Soda sol. . . . . = 7683'000 " " . = 6238'000 " Soda sol. or difference = 1445'000 Sample of Soda sol. analyzed = 140' cc Weight of tubes at end = 258'35 " '* beginning ..... = 257'50 Carbon dioxide absorbed or difference . = 000'85 Carbon dioxide in Soda sol. used . . . = 877 End of Experiment. Duration of experiment ..... 21 hours. Weight of animal = 0'529 " excreta = 0'038 MM. Barometer 758 Pressure in gauge ...... 10 Elastic force of gas in chamber .... 748 Temperature of chamber ..... 18°C Vol. of gas of chamber lit. at standard = 42'53 temp, and press. Analysis of Sample Gas. Barometer ........ 762'mni'6 Temperature of laboratory ..... 18°5 1891/ NATURAL SCIENCES OF PHILADELPHIA 27 Pressure of aq. vapor ...... 15'mm'8 Vol. of sample of gas at observed temp, and press. = 71 cc Vol. of sample reduced to stand. temp, and press, before absorp- - 65'32 cc tion of carbon dioxide. Vol. of sample after absorption of carbon dioxide. = 64'40 cc Carbon dioxide absorbed. - 00'92 cc Vol. of sample after absorption of Oxygen. , = 51'71 cc Oxygen absorbed. = 12'69 cc Composition of Gas of Chamber. Volume of Gas of chamber. 42530 - - 651 Volume of Gas of sample. 65'32 LIT. GRAMMES. 0'92 651 = 0'6 1'966 = 1'179 = Carbon dioxide, v 12'69 651 = 8'2 1'429 = 11'789 = Oxygen. C . in, v ° i ch Arn dpt* 51'71 651 33'6 1'256 = 42'238 = Nitrogen. ) cnamuer. Composition per volume. Composition per cent. Carbon dioxide. 0'60 1'4 Oxygen. 8'25 19'5 Nitrogen. 33'62 79'1 42'47 100'0 GRAMMES. Weight of Oxygen delivered to chamber from Pipette = 25'297 " " in chamber at beginning of exp. = 12'739 " " available = 38'036 " in chamber at end of exp. = 11'789 " " consumed by animal = 26'247 " " " " " per hour = 1'249 " " " " " " " per kilo. = 2'202 " Pipettes and Soda'sol. = 7712'000 " = 6238'000 " Soda sol. or difference = 1474'000 28 PROCEEDINGS OF THE ACADEMY OF [1891. Weight of sample of Soda sol. analyzed 140 cc " Tubes at end = 257'72 " " at beginning = 254'20' Carbon dioxide absorbed or difference = 003'50 1474 gr. of Soda sol. at end contained Carbon dioxide - 37'060 1445 " " at beg. " " = 8'770 Carbon dioxide produced by animal = 28'280 " " absorbed by Soda sol. rem. in chamber = 1T79 Total CO2 produced by animal = 29'459 Weight of Oxygen in Carbon dioxide produced = 2T424 Weight of Oxygen in Carbon dioxide produced 21'424 = Resp. Quot. = = 0'816 Weight of Oxygen consumed • 26'247 Weight of Nitrogen in chamber at beginning - 42'22 " " " at end = 42'20 00'02 W. of CO2 produced by animal per hour = 1'402 W. of CO2 produced per hour per kil. of animal = 2'472 In order to test the accuracy of the method of experimentation just described by control experiments the authors burned within the chamber a given weight of stearic acid. 6'gr'7 of stearic acid (Ci8 H36 O2) when burned should theoretically produce 18'9 gr. CO2. When burned in the chamber of the respiratory apparatus, that amount of stearic acid actually produced 18'5 gr. of CO2. The loss 0'gr'4 CO2 or 2'1. pc. was not, therefore, greater than what might been have anticipated. The animals experimented with, rabbits, monkeys, pigeons, tur- tles, enjoying good health at the beginning of the experiment, did not appear to suffer in any way from their sojourn in the chamber of the respiratory apparatus. The food placed in the chamber when the animals had not been previously fed was in some instances not eaten, the animal apparently not being then hungry. The period of experimentation extended through the winter, spring and summer months of 1890. The hour of experiment selected, day or night, de- pended upon the convenience and the amount of time at the dis- posal of the experimenters. 1891.] NATURAL SCIENCES OF PHILADELPHIA. 29 Experiment No. 1. Jan. 15th. Rabbit. Weight of animal ....... 2 kil o Weight of food ....... 0,kil 0 Duration of experiment 7 hours, day. Difference between the initial and final temperature of the gas of the chamber .... +0o,5 C. Difference between the initial and final pressure of the gas of the chamber .... 1 -mm-5 Composition of gas of chamber at the Composition end of the experiment per cent Carbon dioxide 0'807 Carbon dioxide 2'00 Oxygen 7'331 Oxygen 18'00 Nitrogen 33'737 Nitrogen 80'00 41'875 100'00 GRAMMES. Weight of oxygen consumed .... 15'994 Weight of carbon dioxide produced . . . 19'762 AVeight of oxygen contained in the carbon dioxide 14'372 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed .... 0'898 Weight of oxygen consumed per hour . . 2'284 AVeight of oxygen consumed per hour per kilo- gramme of animal 0'913 AVeight of carbon dioxide produced per hour . 2'823 AVeight of carbon dioxide produced per hour per kilogramme of animal . . . . 1'129 Experiment No. 2. Jan. 20th. Rabbit. AVeight of animal . 2.kiI'4 AVeight of food, turnips ..... O.kil-4 Duration of experiment ... 12 hrs. 45 min. night. Difference between the initial and final tempera- ture of the gas of the chamber . . . -J-0°'5 Difference between the final and initial pressure of the gas of the chamber .... 30 PROCEEDINGS OF THE ACADEMY OF [1891. Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0'649 Carbon dioxide 1'6 Oxygen 7'755 Oxygen 19'0 Nitrogen 32'333 Nitrogen 79'4 40'737 100'0 GRAMMES. Weight of oxygen consumed ..... 31'53 Weight of carbon dioxide produced . . . 35'26 Weight of oxygen contained in the carbon dioxide 25'65 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed .... 0'81 Weight of oxygen consumed per hour . . . 2'48 Weight of oxygen consumed per hour per kilo- gramme of animal ..... 1'03 Weight of carbon dioxide produced per hour . 2'76 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 1'15 Experiment No. 3. Jan. 24th. Rabbit. Weight of animal ....... 2.kll'3 Weight of food 0.kil 0 Duration of experiment . 7'5 hrs., day. Difference between the initial and final temperature of the gas of the chamber .... 0°'5 C. Difference between the initial and final pressure of the gas of the chamber ..... -]-10mra' Composition of gas of chamber at the Composition end of the experiment per cent Carbon dioxide 0'448 Carbon dioxide 1'00 Oxygen 8'655 Oxygen 20'10 Nitrogen 34'036 Nitrogen 78'90 43'139 100-00 GRAMMES. Weight of oxygen consumed 9'219 Weight of carbon dioxide produced . . . 10'706 Weight of oxygen contained in the carbon dioxide 7'786 1891.] NATURAL SCIENCES OF PHILADELPHIA 31 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed .... 0'844 Weight of oxygen consumed per hour . . . 1'229 Weight of oxygen consumed per hour per kilo- gramme of animal ...... 0'534 Weight of carbon dioxide produced per hour . 1'427 Weight of carbon dioxide produced per hour per per kilogramme of animal .... 0'620 Experiment No. 4. Feb. 3rd. Rabbit. Weight of animal ....... 2'RiL6 Weight of food ....... 0'kil' Duration of experiment 7'5 hrs., day. Difference between the initial and final tempera- ture of the gas of the chamber . . . -|-2°C. Difference between the initial and final pressure of the gas of the chamber .... l'mm'8 Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0'98-3 Carbon dioxide 2'3 Oxygen 7'244 Oxygen 17'3 Nitrogen 33'787 Nitrogen 80'04 42'014 100'00 GRAMMES. Weight of oxygen consumed ..... 15'00 Weight of carbon dioxide produced . . . 19'80 Weight of oxygen contained in the carbon dioxide 14'40 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed ..... 0'96 Weight of oxygen consumed per hour . . . 2'00 Weight of oxygen consumed per hour per kilo- gramme of animal ...... 0'70 Weight of carbon dioxide produced per hour . 2'64 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 1'01 32 PROCEEDINGS OF THE ACADEMY OF [1891. Experiment No. 5. Feb. 5th. Rabbit. Weight of animal 2'k,L3 Weight of food, turnips O'kiL2 Duration of experiment 11 hours, day. Difference between the initial and final tempera- ture of the gas of the chamber . . . 4-1° C. Difference between the initial and final pressure of the gas of the chamber ..... _p4-n»»-4 Composition of gas of chamber at the Composition end of the experiment per cent Carbon dioxide 0'886 Carbon dioxide 2'1 Oxygen 7'763 Oxygen 18'7 Nitrogen 32'853 Nitrogen 79'2 41'502 100'0 GRAMMES. Weight of oxygen consumed 22'534 Weight of carbon dioxide produced . . . 28'132 Weight of oxygen contained in the carbon dioxide 20'459 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed .... 0'907 Weight of oxygen consumed per hour . . . 2'048 Weight of oxygen consumed per hour per kilo- gramme of animal 0'890 Weight of carbon dioxide produced per hour . 2'557 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 1'111 Experiment No. 6. Feb. 7 th. Rabbit. Weight of animal ....... 2'kiL5 Weight of food . O'kil'O Duration of experiment ..... 9 hrs. Difference between the initial and final tempera- ture of the chamber ..... 4-l°C* Difference between the initial and final pressure of the gas of the chamber .... 4-8""' 1891.] NATURAL SCIENCES OF PHILADELPHIA. Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0'919 Carbon dioxide 2'15 Oxygen 7'849 Oxygen 18'87 Nitrogen 33'963 Nitrogen 79'48 42'731 Lit. 100'00 GRAMMES. Weight of oxygen consumed ..... 18'526 Weight of carbon dioxide produced . . . 24'010 Weight of oxygen contained in the carbon dioxide 17'470 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed ..... 0'957 Weight of oxygen consumed per hour . . . 2'058 Weight of oxygen consumed per hour per kilo- gramme of animal ...... 0'823 Weight of carbon dioxide produced per hour . . 2'668 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 1'067 Experiment No. 7. Feb. 10th. Rabbit. Weight of animal ....... 2'kU'2 Weight of food, turnips ..... O'kiL2 Duration of experiment . . . . 11 hours, night. Difference between the initial and final tempera- ture of the gas of the chamber ... 0° C. Difference between the initial and final pressure of the gas of the chamber .... -|-5mm' Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0'823 Carbon dioxide 2'00 Oxygen 7'279 Oxygen 17'00 Nitrogen 34'956 Nitrogen 81'00 43'058 100'00 GRAMMES. Weight of oxygen consumed ..... 20'53 Weight of carbon dioxide produced . . . 24'60 33 34 PROCEEDINGS OF THE ACADEMY OF [1891. Weight of oxygen contained in the carbon dioxide 17'90 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed ..... 0'87 Weight of oxygen consumed per hour . . . 1'86 Weight of oxygen consumed per hour per kilo- gramme of animal ...... 0'84 Weight of carbon dioxide produced per hour . . 2'23 Weight of carbon dioxide produced per hour per » kilogramme of animal ..... 1'01 Experiment No. 8. Feb. 14th. Rabbit. Weight of animal . 2'k,L5 Weight of food, fed before experiment . Duration of experiment .... 1'15 hrs., night. Difference between the initial and final tempera- ture of the gas of the chamber ... 0° C. Difference between the initial and final pressure of the gas in the chamber + llmm' Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0'889 Carbon dioxide 2'00 Oxygen 7'946 Oxygen 19'00 Nitrogen 32'911 Nitrogen 79'00 41'646 100'00 GRAMMES. Weight of oxygen consumed ..... 21'58 Weight of carbon dioxide produced . . . 26'75 Weight of oxygen contained in the carbon dioxide 19'45 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed ..... 0'90 Weight of oxygen consumed per hour . . . 1'86 Weight of oxygen consumed per hour per kilo- gramme of animal ...... 0'74 Weight of carbon dioxide produced per hour . . 2'32 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 0'92 1891.] NATURAL SCIENCES OF PHILADELPHIA. 35 Experiment No. 9. Feb. nth. Rabbit. Weight of animal ......* 2*kil*l Weight of food, turnips q-mi-4 Duration of experiment ..... 12 hrs., night. Difference between the initial and final tempera- ture of the gas of the chamber . . . +4° C. Difference between the initial and final pressure of the gas of the chamber ..... 0*m 0 Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 1*230 Carbon dioxide 3*000 Dxygen 6*033 Oxygen 14*000 Nitrogen 34*165 Nitrogen 83*000 41*428 100*000 GRAMMES. Weight of oxygen consumed 24*396 Weight of carbon dioxide produced . . . 29*310 Weight of oxygen contained in the carbon dioxide 21*316 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed ..... 0*873 Weight of oxygen consumed per hour . . . 2*033 Weight of oxygen consumed per hour per kilo- gramme of animal ...... 0*968 Weight of carbon dioxide produced per hour . . 2*442 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 1*162 Experiment No. 10. March IRA. , Rabbit. Weight of animal 2*kil l Weight of food, turnips ...... Duration of experiment ..... 13 hrs., night. Difference between the initial and final tempera- ture of the gas of the chamber . . . 4-1° C. Difference between the initial and final pressure of the gas of the chamber ..... -f-l'mm*4 36 PROCEEDINGS OF THE ACADEMY OF [1891. Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0'693 Carbon dioxide 1'6 Oxygen 6'672 Oxygen 15'7 Nitrogen 35'076 Nitrogen 82'7 42'441 100'0 GRAMMES. Weight of oxygen consumed ..... 27'21 Weight of carbon dioxide produced . . . 34'12 Weight of oxygen contained in the carbon dioxide 24'81 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed ..... 0'91 Weight of oxygen consumed per hour . . . 2'09 Weight of oxygen consumed per hour per kilo- gramme of animal ...... 0'99 Weight of carbon dioxide produced per hour . . 2'62 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 1 '24 Experiment No. 11. March 20th. Rabbit. Weight of animal 2'kil'4 Weight of food, turnips ...... O^M Duration of experiment ..... 13 hrs., night. Difference between the initial and final tempera- ture of the gas of the chamber . . . -f-0°'5 C. Difference between the initial and final pressure of the gas of the chamber ..... 0'mm 0 Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0'558 Carbon dioxide 1'40 Oxygen 6'810 Oxygen 17'00 Nitrogen 32'592 Nitrogen 81'60 39'960 100'00 GRAMMES. Weight of oxygen consumed ..... 27'939 Weight of carbon dioxide produced . . . 37'208 1891.] NATURAL SCIENCES OF PHILADELPHIA. 37 Weight of oxygen contained in the carbon dioxide 27'242 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed ..... 0'971 Weight of oxygen consumed per hour . . . 2'141 Weight of oxygen consumed per hour per kilo- gramme of animal 0'892 Weight of carbon dioxide produced per hour . . 2'862 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 1'192 Experiment No. 12. April 28th. Rabbit. Weight of animal ....... 2'ki' 00 Weight of food, turnips ...... O'kil12 Duration of experiment . . . . .9 hrs. 45 min., day. Difference between the initial and final tempera- ture of gas in the chamber . . . . +5° C. Difference between the initial and final pressure of the gas of the chamber ..... -f- 3'mm'5 Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 1'194 Carbon dioxide 2'85 Oxygen 7'688 Oxygen 18'39 Nitrogen 32'927 Nitrogen 78'76 41'809 100'00 GRAMMES. Weight of oxygen consumed ..... 17'535 Weight of carbon dioxide produced . . . 21'878 Weight of oxygen contained in the carbon dioxide 15'911 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed ..... 0'907 Weight of oxygen consumed per hour . . . 1'807 Weight of oxygen consumed per hour per kilo- gramme of animal ...... 0'903 Weight of carbon dioxide produced per hour . . 2'254 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 1'127 38 PROCEEDINGS OF THE ACADEMY OF '189U Experiment No. 13. May 2nd. Rabbit. Weight of animal ....... rkiL8 Weight of food, turnips ...... I'^IS Duration of experiment .... 11 hrs. 45 min., night. Difference between the initial and final tempera- ture of the gas of the chamber ... 0° C Difference between the initial and final pressure of the gas of the chamber ..... -jQmm. Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0'567 Carbon dioxide 1'40 Oxygen 7'479 Oxygen 18'58 Nitrogen 32'228 Nitrogen 80'02 40'274 100'00 GRAMMES. Weight of oxygen consumed ..... 27'228 Weight of carbon dioxide produced . . . 39'332 Weight of oxygen contained in the carbon dioxide 28'605 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed ..... 1'050 Weight of oxygen consumed per hour . . . 2'326 Weight of oxygen consumed per hour per kilo- gramme of animal ...... 1'292 Weight of carbon dioxide produced per hour . 3'361 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 1'867 Experiment No. 14. April 1st. Monkey, Cebus capucinus. Weight of animal . 2'kil 00 Weight of food, orange O'kil17O Duration of experiment . . . . . .5 hrs., day. Difference between the initial and final tempera- ture of the gas of the chamber . . . +0°'5 C. Difference between the initial and final pressure of the gas of the chamber + 2mm 1891.] NATURAL SCIENCES OF PHILADELPHIA. 39 Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0'855 Carbon dioxide 2'10 Oxygen 8'422 Oxygen 19'80 Nitrogen 33'117 Nitrogen 78'10 42'394 100'00 GRAMMES. Weight of oxygen consumed ..... 13'47 Weight of carbon dioxide produced . . . 16'389 Weight of oxygen contained in the carbon dioxide 11'919 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed 0'884 Weight of oxygen consumed per hour . . . 2'694 Weight of oxygen consumed per hour per kilo- gramme of animal ...... 1'347 Weight of carbon dioxide produced per hour . . 3'277 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 1'638 Experiment No. 15. April 3rd. Monkey, Cebus capucinus. Weight of animal ....... l'kll'5O Weight of food, sweet potatoes .... O'klL158 Duration of experiment .... 6 hrs. 20 min., day. Difference between the initial and final tempera- ture of the gas of the chamber . . . +3° C. Difference between the initial and final pressure of the gas of the chamber + lmm- Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0'418 Carbon dioxide 0'98 Oxygen 8'759 Oxygen 20'61 Nitrogen 33'324 Nitrogen 78'41 42'501 100'00 GRAMMES. Weight of oxygen consumed ..... 14'31 Weight of carbon dioxide produced . . . 18'73 40 PROCEEDINGS OF THE ACADEMY OF [1891. Weight of oxygen contained in the carbon dioxide 13'62 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed ..... 0'95 Weight of oxygen consumed per hour . . . 2'27 Weight of oxygen consumed per hour per kilo- gramme of animal 1'51 Weight of carbon dioxide produced per hour . . 2'97 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 1'98 Experiment No. 16. May 26 th. 2 Pigeons. Weight of animals ....... O'kil'57O Weight of food, corn 0,kU180 Duration of experiment . . . . 13 hrs. 15 min., day. Difference between the initial and final tempera- ture of the gas of the chamber . . . 4-0°'5 C. Difference between the initial and final pressure of the gas of the chamber ..... -|-19'mm 00 Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0'630 Carbon dioxide 1'42 Oxygen 9'447 Oxygen 21'37 Nitrogen 34'131 Nitrogen 77'21 44'208 100'00 GRAMMES. Weight of oxygen consumed ..... 26'6804 Weight of carbon dioxide produced . . . 32'1564 Weight of oxygen contained in the carbon dioxide 23'1592 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed ..... 0'8680 Weight of oxygen consumed per hour . . . 2'0218 Weight of oxygen consumed per hour per kilo- gramme of animal 3'5470 Weight of carbon dioxide produced per hour . . 2'3471 Weight of carbon dioxide produced per hour per kilogramme of animal 4'1178 1891.] NATURAL SCIENCES OF PHILADELPHIA. 41 Experiment No. 17. Oct. 29th. 2 Pigeons. Weight of animal 0'kil'567 Weight of food ....... O'kiLO Duration of experiment ._..... 21 hrs. Difference between the initial and final tempera- ture of the gas of the chamber . . . 0°'0 Difference between the initial and final pressure of the gas of the chamber 0-mm 0 Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0'60 Carbon dioxide 1*4 Oxygen 8'25 Oxygen 19'5 Nitrogen 33'62 Nitrogen 79'1 42'47 100'0 GRAMMES. Weight of oxygen consumed ..... 26'247 Weight of carbon dioxide produced . . . 29'459 Weight of oxygen contained in the carbon dioxide 21'424 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed 0'816 Weight of oxygen consumed per hour . . . 1'249 Weight of oxygen consumed per hour per kilo- gramme of animal ...... 2'202 Weight of carbon dioxide produced per hour . . 1'402 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 2'472 Experiment No. 18. April 7 th. Turtle, Pseudemys Mobilensis. Weight of animal pHi? Weight of food, sweet potato ..... 0'ki' l Duration of experiment 96 hours. Difference between the initial and final tempera- ture of the gas of the chamber ... 0'° C. Difference between the initial and final pressure of the gas of the chamber ..... +19'mm,00 42 PROCEEDINGS OF THE ACADEMY OF [1891. Composition of gas of chamber at the Composition end of the experiment: per cent: Carbon dioxide 0*366 Carbon dioxide 0*85 Oxygen 9*623 Oxygen 22*41 Nitrogen 32*954 Nitrogen 76*74 42*943 100*00 GRAMMES. Weight of oxygen consumed ..... 8*612 Weight of carbon dioxide produced . . . 11*341 Weight of oxygen contained in the carbon dioxide 8*248 Ratio between the weight of the oxygen contained in the carbon dioxide produced, and the weight of the oxygen consumed ..... 0*957 Weight of oxygen consumed per hour . . . 0*088 Weight of oxygen consumed per hour per kilo- gramme of animal ...... 0*051 Weight of carbon dioxide produced per hour . 0*118 Weight of carbon dioxide produced per hour per kilogramme of animal ..... 0*063 Resume of 13 Experiments as regards the Consumption of Oxygen and Production of Carbon Dioxide by Rabbits. O, consumed per hour. O, consumed per hour per kil. of animal. CO2, produced per hour. CO2, produced per hour per kil. of animal. Resp. Quot Exp. GRAMMES. GRAMMES. GRAMMES. GRAMMES. No. 1. 2-28 0-91 2-82 1-12 0-89 " 2. 2-48 1-03 2-76 1-15 0-81 " 3. 1-22 0-53 1-42 0-62 0-84 " 4. 2-00 0-70 2-64 1-01 0-96 " 5. 2-04 0-89 2-55 1-11 0-90 " 6. 2-05 0-82 2-66 1-06 0-95 " 7. 1-86 0-84 2-33 1-01 0-87 " 8. 1-86 0-74 2-32 0-92 0-90 " 9. 2-03 0-96 2-44 1-16 0-87 " 10. 2-09 0-99 2-62 1-24 0-91 " 11. 2T4 0-89 2-86 1-19 0-97 " 12. 1-80 0-90 2-25 1-12 0-90 " 13. 2-32 1-29 3-36 1-86 1-05 Total, 26-17 11-49 33-03 14-57 11-82 1891.] NATURAL SCIENCES OF PHILADELPHIA. 43 26-17 11-49 33-03 Average = = 2-gr-01 = 0-gn88 = 2-gr53 13 13 13 14-57 11-82 = l-gr-12 = 0-90 13 13 It will be observed from the above resume that the rabbit con- sumes upon the average 2-gr-01 of oxygen per hour and 0-gr 8 of oxygen per hour per kilogramme of body weight and produces 2,gr-5 of carbon dioxide per hour and l-gr-l of carbon dioxide per hour per kilogramme of body weight, the respiration quotient or the ratio between the weight of the oxygen contained in the carbon dioxide pro- duced and the weight of the oxygen consumed amounting on the aver- age to 0'9. In this connection it may be mentioned that the rabbit con- sumes on the average the same amount of oxygen and produces the same amount of carbon dioxide whether the gas breathed, be the atmosphere as under ordinary circumstances, or pure oxygen as in the case of the animal being placed within the chamber of the respiratory apparatus. As the respiratory process in man does not differ from that of the rabbit, at least in its chemical aspects, there is no reason to suppose that any more oxygen would be consumed by man if breathed alone than when breathed as mixed with nitro- gen as obtains in the breathing of ordinary air. Notwithstanding that the experiments with the rabbits were performed at different seasons of the year, at different hours of the day or night, that food was or was not eaten, that in some instances the animals were more lively and active than in others, in a word, that the conditions in general varied considerably, nevertheless, it will be seen that the respiratory quotient varied but little in the different experiments. It may be mentioned that the respiratory quotient as given by Reg- nault & Reiset, Rauber, Colosanti, Richet, Regnard and others dif- fers but little from that obtained by the authors. Attention is also called to the fact of the consumption of oxygen and production of carbon dioxide being increased by the taking of food-example 6 as compared with example 12 offers the only exception. The ani- mal in the former case, however, weighed more than in the latter. Inasmuch as in their next communication the authors propose to give a detailed account of their observations upon the respiration of monkeys as studied by means of the Voit apparatus, attention is simply called to the fact that the respiratory quotient (Exps. 14, 15) differs but little, if at all, from that of the rabbit. With refer- [1891. 44 PROCEEDINGS OF THE ACADEMY OF ence to the experiments with the pigeons (Exps. 16, 17) apart from the fact (of little significance) that one experiment was performed in May and the other in October it should be mentioned that in the first instance the pigeons were fed and were much more active than in the second which accounts for the weight of the oxygen consumed and car- bon dioxide produced being so much greater in the former case than in the latter, the respiratory quotient being 0'8. The apparatus made use of by the authors in the investigations just described is not well adapted to the study of respiration as obtained in the lower verte- brata, reptilia, batrachia and invertebrata. Nevertheless, the re- sults of an experiment (Exp. 18) with a turtle (Pseudemys mobil- ensis) are offered as illustrating how slowly oxygen is consumed and carbon dioxide is produced in such animals, the respiratory quo- tient, however, being the same as in the mammalia. CHAPMAN AND BRUBAKER ON RESPIRATION. PROC. ACAD. NAT. SCI. PHILA. 1891 PL. II. CHAPMAN At[D BRUBAKER ON RESPIRATION. CHAPMAN AND BRUBAKER ON RESPIRATION.