Fig. 81. 



170 EXPERIMENTS OF REGNAULT AND EEISET. 



Effect of rot tem wnen res pi re( l tnan even oxygen itself, on account of its 

 oxide of nitro- ready condensibility by pressure, or by membranes, and sol- 

 ubility in water, the circulation is greatly quickened at first, 

 and a state of exhilaration ensues ; but this is soon followed by a con- 

 dition of depression, or even of coma, for the quantity of carbonic acid 

 produced in the system is now so great that the lungs are wholly inade- 

 quate to effect its removal, and all the symptoms of poisoning by car- 

 bonic acid come on. 



Zimmerman found that a rabbit exhaled 12 J grains of carbonic acid 

 per hour when breathing atmospheric air, but that the quantity rose at 

 once to 20 grains per hour when it was caused to breathe protoxide of 

 nitrogen. But by far the most complete and important series of experi- 

 Summary of ments yet made in regard to the relations of the aerial me- 

 Regnauit's and dium and the respiring animal is that of MM. Eegnault and 

 iments or; res- Reiset, published in the Annales de Chimie, Juillet, 1849, of 

 piration. which, since it may be taken as a model of physiological in- 



vestigation, a brief abstract is here given. 



The apparatus they 

 employed is represented 

 in Fig. 81. It possesses 

 the great advantage over 

 all experimental arrange- 

 ments heretofore employ- 

 ed in permitting an ani- 

 mal to be kept even for 

 many days in a limited 

 volume of air, but under 

 such circumstances that 



Experiments on respiration. that ail* WaS Constantly 



kept at its normal composition by the automatic motions of the instru- 

 ment itself: oxygen being thus furnished as it was required, and car- 

 bonic acid removed. 



The arrangement consists of three parts : 1st, a chamber or bell, Z, for 

 inclosing the animal, surrounded by a jar filled with water, the tempera- 

 ture of which could be ascertained by a thermometer, L In the interior 

 of the bell was a platform perforated with holes, by the aid of which the 

 'excretions could be collected. On one side, at^>, was a pressure gauge, 

 connected with the bell by a tube, and showing the condition of conden- 

 sation or rarefaction of the included atmosphere. 2d. At the same side, 

 the bell communicated, by means of India-rubber tubes, m, n, with two 

 cylindric vessels, q, r, filled with a solution of caustic potassa, and which 

 were driven by the aid of powerful clock-work in such a way that the 

 one alternately rose and the other descended, the flexible tube s permit- 



