180 CHANGES PRODUCED IN AIR BY RESPIRATION. 



IV. 



On the Changes produced in Atmospheric Air, end Oxigcii 

 Gas, by Respiration. By W. AlleN, Esq., F. R.S., and 

 W. H. PepVs, Es qi , F. R. S*. 



Respiration J|_ HE process of respiration, Or breathing, is so intimately 

 tinted " mVCI " connected wittl our existence in life, that from its first mo-» 

 ments to the final close, sleeping and waking, this necessary 

 action is constantly maintained: nor can it be suspended 

 even for a few minutes without considerable pain and the 

 utmost danger. This important process has of course ex- 

 cited the curiosity both of ancient and modern philosophers ; 

 among the latter we find the distinguished names of Ma vow, 

 fcjmany, Priestley, Goodwin, Menzies, Spallanzani, Scheele, Lavoi- 



sier, and Davy, whose successive labours have thrown great 

 light upon this difficult subject, and prepared the way for 

 farther investigation ; but it is impossible to take a review 

 of what has already been done, without perceiving, that somte 

 but some im- * m P ortant points were by no means satisfactorily settled ; an 

 portant points accurate method of separating the different gasses, and as- 

 still unsettled. cer t a ining their exact proportion in any given mixture, was 

 still a desideratum when many of the experiments were 

 made; and it is only of late years that eudiometry has at- 

 Residual pas in * ame( l its present perfection. The quantity of residual gas 

 the lungs often in the lungs after a forced expiration was a matter in dis- 

 a lfncu ty. ^^ e amon g f orme r experimenters, come making it one hun- 

 dred and nine cubic inches, and others only forty ; and yet 

 it is of the utmost importance in all calculations upon the 

 effects produced, especially upon small portions of gas, that 

 the state of the lungs should be accurately determined ; this 

 constitutes the great difficulty in the investigations. We 

 this obviated, therefore commenced our labours by constructing an appa- 

 tus, in which we are able to respire from three to four thou- 

 sand cubic inches of gas, conceiving, that in this quantity, 

 the errour arising from the residul gas in the lungs must be 

 so much obviated as to permit the most satisfactory results. 



» Philos. Trans, for 1808, p. 249. 



The' 



