and Oxygen Gas ly Resplraiioti. 24 £ 



appears, whenever atmospheric air is taken into the lungs, 

 it returns charged with about 8 per cent, carbonic acid. 

 The faster respiration is performed, the more carbonic acid 

 is given off, and consequently the more oxygen consumed : 

 in this instance it was given off at the rate of fifty-one 

 cubic inches per minute. 



Thirteenth Ex-perimmt . 

 We now proceeded to carry on the respiration of common, 

 air for a much longer period than usual, and of course on a 

 much larger quantity. The experiment was made by the 

 same operator who had performed all the other, except the 

 12th. Eleven mercurial gasometers having been rilled, taken 

 off, and registered, the operator continued to breathe in the 

 1 2th until a mark was made by his colleague upon die scale 

 of the water gasometer, and it was again filled with common 

 air to the usual division on the scale. This occupied but a 

 very short space of time. The operator, without taking his 

 lips from the tube, then filled twelve more of the mercurial 

 gasometers, which were registered as before, and he conti- 

 nued to breathe in the 12th, until the water gasometer was 

 again replenished ; eleven more were then tilled, and por- 

 tions saved from each : the experiment was completed by a 

 forcible expiration of 16/5 cubic inches into the 12th ; and 

 this last portion being left for an hour and a half was not 

 perceptibly diminished in volume. 



„,, Cubic incites ~ , . . . 



„ Therm n ,- c • Cubic mch.es .-, r . 



J3arom. ^ , lime. of common air . , Deficiency. 



rahr - inspired. e ^ lred ' 



29*85 68° 24-'-37" 9*90 9872 IS 



The breathing was so nearly natural that the operator was 

 scarcely fatigued, and thought that he could have gone on 

 for a much longer time. 



The smallness of the deficiency, notwithstanding the ex- 

 periments . occupied ,24-|- minutes, is a striking circum- 

 stance, and leads us to suspect still more strongly, that 

 the deficiency principally arises from the impossibilitv of 

 always bringing the lungs to the same state after forcible 

 ejrni ration. 



100 parts 



