n 4°4i 3 
XXV. On Respiration. By William Allen, Esq. F.R.S. and 
William Hasledine Pepys, Esq. F. R.S. 
Read June 22, 1809. 
One of the most prominent features in our last communica- 
tion was the evolution of a considerable quantity of azote, when 
oxygen gas nearly pure was respired ; and although a consi- 
derable part of this azote must undoubtedly be attributed to 
the residual gas in the lungs, after the most forcible attempt 
at expiration, yet the fact seemed to demand still farther in- 
vestigation, it appearing of consequence to ascertain whether 
the increase of azote was uniform throughout the latter stages 
of the experiment, or solely confined to the earlier periods. 
By adverting to our former Paper, it will be found, that in 
an experiment where more than 3000 cubic inches of oxygen 
passed through the lungs in seven minutes and a quarter, 62 
cubic inches of azote were found in the first 250 cubic inches 
expired, though the gas originally contained but 2,5 per cent, 
or only 6 cubic inches in this quantity ; in the two next por- 
tions expired, consisting of 562 cubic inches, we found 56 
cubic inches of azote, though this quantity of gas, before it 
was respired, contained only 14,; these, first portions, were 
given off in about two minutes, and contained nearly 100 
cubic inches of azote more than could be accounted for in the 
oxygen employed; hence it is plain, that a large proportion 
of the increase is evolved in the first periods of the process. 
