<25Z 



PFAFF ON RESPIRATION. 



Thcfe refulls agree very well with thofe obtained by Davy 

 on the diminution of air by refpiration. He found the diminu- 

 tion by one fingle refpiration to be ^ part, and by refpiration 

 continued for one minute -± s part. 



The magnitude of the diminution depends not only on the 

 time during which a given volume of air is refpired, but 

 principally on the magnitude of this volume itfelf ; it rauft 

 be proportionally Iefs the greater the quantity of air infpired. 

 A very efTential error is feen in the refults of Abernethy, who 

 gives a greater volume to the expired than to the infpired 

 air; and the calculations of Goodwin are founded on a 

 miilaken bafis; for he fuppofes the two volumes equal. 

 Diminution of j n or( ] er to determine comparatively the diminution of 

 refpiration. oxigen gas by refpiration, 170 cubic inches of oxigen gas 

 obtained from manganefe were refpired in the fame manner, 

 and under the fame circumftances as the 170 cubic inches 

 of atmofpheric air in the 5lh paragraph. The diminution 

 amounted to 30 cubic inches, and in other experiments, to 

 33, 29, 31. The mean term of which is T 2 T parts of the 

 primitive volume. 



This diminution being eftablifhed with accuracy, may be 

 applied to determine the abforption of azote gas. 

 Experiments to 8. SO Cubic inches were refpired one time llowly during 

 determine how t or 12 f ec0 nds, and the air expired was received over 



much azote is * 



abiwbed in the mercury. 



procefs of ref- ji^ relative quantity of the conftiluent parts of this refr 

 piled air was in the centenary 4,16 carbonic acid, 16,55 

 oxigen gas obferved by the flow combuftion of phofphorus, 

 79,19 of azote gas. An eudiometric experiment made at the 

 fame time, gave the following proportion of the parts in 

 atmofpheric air, one carbonic acid, 21 oxigen gas, and 78 

 azote. The total diminution of the air was from the pre- 

 ceding experiments ^. We may therefore find the true 

 quantity of azote gas by the following proportion, 36 : 35 :: 

 79,19 : 76,99. If we fubtract this 76,99 from 78, the pri- 

 mitive quantity of azote in the atmofpheric air before ref- 

 piration, we find a lofs of 1,01 on the hundred parts of the 

 whole mafs of air breathed. But as the quantity of air in- 

 fpired was really no more than 80 cubic inches, the abfolute 

 djrr ; n,ution or difappearance of azote gas by one refpiration^ 



muft 



