248 On the Changes produced in Atmospheric Air 



In this experiment the operator inspired 3460 cubic inches 

 in eleven minutes, ami felt himself in a natural state when 

 he left off. Then, as he makes usually under common cir- 

 cumstances nineteen respirations in a minute, 



11 X 19 = 209 — = 16-5 



209 



it follows, that he takes in 16'-,^ cubic inches at every easy in- 

 spiration. 



As all the experiments had been hitherto made upon the 

 lungs of one person, we concluded that the next should be 

 performed upon our assistant. 



Twelfth Experiment. 



~, Cubic inches „ , . . , 



■r, I herm. ,_. r . Cubic inches -,-v/r 



Barom. ,. , Time. of common air . , Difference. 



1-ahr. • • j expired, 



inspired. r 



30*3 56° b\ -min. 3300 3311 1 1 increase. 



Here, as usual, the lungs were exhausted both before, and at. 

 the close of the experiment. 



The excess of eleven cubic inches, in this case, no doubt 

 arose from the person not having been in the habit of ex- 

 hausting his lungs, so that they contained more when he 

 began than when he left off; his lungs appeared to be of 

 greater capacity than those of the usual operator. 



Portions of eas were saved from each of the mercurial 

 gasometers as they were filled, which being mixed together, 

 for the average gave the following results : 

 100 parts of the mixture contained 

 8*5 carbonic acid. 

 12-5 oxygen. 

 79' azote. 



100 



Calculation for Carlonic Acid. 



100 : 8-5 : : 3311 : 281*43. 



Consequently 281-43 cubic inches of carbonic acid gas were 



given off in b\ minutes. 



In this experiment we meet with a remarkable fact, viz. 

 that as much carbonic acid gas was given off in 54- minutes, 

 as in the former experiment in eleven minutes : so that it 



appears, 



