ANIMAL HEAT. 201 



exhaled from the mucous membrane of the mouth and pha- 

 rynx, resembling the watery exhalation which takes place 

 from the peritonaeum, or any other internal surface when ex- 

 posed j and this conclusion appears to be fully confirmed by 

 the experiments of M. Magendie, lately communicated to the 

 National Institute of Paris. 



These circumstances are of importance in the present com- c j iar ,g es j n t j if 

 munication, which they render more simple, as they show, that air tiom res- 

 in order to ascertain the changes produced on the air in respira- {"/Educed* 

 tion, it is only necessary to find the quantity of carbonic acid from the car*- 

 given out from the lungs. This becomes an exact measure of ?™£ ^ 

 the oxygen consumed, and the azote of the air and the watery 

 vapour expired, need not be taken into the account. 



For the purpose of examining the changes produced on the 

 air, by animals breathing under the different circumstances 

 abovementioned, I contrived the apparatus, which is represented 

 in the annexed Plate. Plate VI. Fig. I . 



Description of the apparatus. 



A. Is a wooden stand in which is a circular groove J of an Apparatus, 

 inch in depth, and the same in width. 



B. Is a bell-glass, the rim of which is received in the circular 

 groove of the wooden stand. In the upper part of the bell- 

 glass is an opening, admitting a tu4>e connected with the blad- 

 der C. 



D. Is a bottle of elastic gum, having a brass stop-cock E 

 connected with it. 



F. Is a silver tube, of which one end is adapted to receive* 

 the tube of the stop-cock E, while the other extremity, making 

 a right angle with the rest of the tube, passes through a hole 

 in the wooden stand, and projects into the cavity of the bell- 

 glass, where it makes a second turn, also at a right angle, and 

 becomes of a smaller diameter. In the upright part of the 

 tube is an opening G. 



The tubes are made perfectly air-tight, where connected 

 m with each other, and with the rest of the apparatus, and the 

 circular groove is filled with quicksilver. 



The capacity of the bell-glass, allowance being made for 

 the rim, which is received in the groove with the quicksilver, 

 is found to be 502 cubic inches. The capacity of the gum- 



Vol. XXXIV.— No. 158. P bottle 



