PFAFF ON RESPIRATION 251 



made for the moft part in the prefence of my pupils, par- 

 ticularly one named Dierks, who was moil commonly the Tub- 

 ject of experiment. 



In order to determine with precifion the changes which 

 atmofpheric air undergoes by refpiration, and to decide re- 

 fpecling the abforption of azote gas, we muft begin with 

 ascertaining the diminution which a given volume of air 

 undergoes by refpiration. Thisfirft point was to be determin- 

 ed by accurate experiments. 



1. The quantity of 170 duodecimal cubic inches of Paris* Quantity of 

 were refpired from one of the great refervoirs of a gafometer, un( j ergone j, y 

 conducted at Paris after the model of that of Charles, over air by the 

 water covered with oil, to prevent the abforption of thejjr^^ xe *" 

 carbonic acid gas produced by refpiration. The refpiration 



was performed once only during the time of ten or twelve 

 feconds. The diminution was 4,72 cubic inches, or -^ part 

 of the firft volume. This experiment being repeated twenty 

 times in the fame manner, afforded the fame refultf. 



2. 144- Cubic inches were refpired once in the fpace of 

 ten or twelve feconds. The diminution was four cubic inches 

 or j J s part of the primitive volume. 



3. The fame volume was refpired twice during 22 feconds, 

 and the diminution amounted to eight cubic inches, or T * ¥ 

 part of the primitive volume. The fame volume having been 

 refpired three times during 30 feconds, the diminution amount- 

 ed to 12 cubic inches, or ^ part of the primitive volume. 



4. 60 Cubic inches were refpired three times during 23 

 feconds, the diminution was fix cubic inches, or f 5 of the 

 primitive volume. 



5. 170 Cubic inches were refpired four times during one 

 minute, and the diminution amounted to 20 cubic inches. 



This experiment was feveral times repeated, and the dimi- 

 nution was almoft conftantly the fame. Namely, IS, 19, 

 21 , and 20 cubic inches, or T * 7 . 



6. 168 Cubic inches refpired during 50 feconds, by four 

 great and four fmall refpirations, fufTered a diminution of 14, 

 or T \- of the primitive volume. 



7. 430 Cubic inches by 12 refpirations in 90 feconds, 

 fufFered a diminution of 24, or -^ part. 



* As thefe quantities are merely relative, I haye not deduced 

 them, J. 



Thefe 



