518 Dr. W. Marcet on the Function of Respiration at [Apr. 24, 



cent. The volume of air expired in the case of the guide exhibits a 

 similar change, amounting to 22 6 per cent., but the decrease stops at 

 Gnajara, the intermediate station. The total mean volume of air 

 expired per minute, at every station (the foot of the cone excepted), 

 while in a sitting posture, was for myself 5 '36 litres, and for the guide 

 675 litres. 



8. The percentage of carbonic acid in the air expired exhibits 

 nearly the same changes on the Island of Teneriffe as in the Alps. 

 At Teneriffe it rose from 4'1 per cent, at the seaside to 4*9 per cent, 

 at 11,945 feet, while, in the Alps, the proportion had varied from 

 3*8 per cent, at 1,230 feet to 47 per cent. (St. Bernard) at 9,403 

 feet. If the total mean proportion of carbonic acid in the air expired, 

 reduced, for the three stations of Alta Yista, Guajara, and Puerto be 

 calculated, it will be found to amount, for myself, to 4*4 per cent, and 

 for the guide to 4" 6 per cent., or to be nearly the same. The mean 

 from the eighty-nine experiments I made in the Alps, in the sitting 

 posture, yielded 4" 2 per cent, of carbonic acid expired. 



9. The frequency of the expirations fell considerably in both cases 

 at the seaside, or increased on rising above the sea, but was much the 

 same for each of us respectively at the different stations on the Peak. 

 The reduction at the seaside, from the mean frequency of respiration 

 at the upper stations, amounted for myself to 31*2 per cent., and for 

 the guide to 25*5 per cent. In the Alps there had been a somewhat 

 gradual rise of the frequency of the respirations between the lowest 

 and highest stations, equal in my case to 34*9 per cent. 



10. While raising with the feet a weight of 39'5 lbs. to an elevation 

 of 5*06 inches forty-five times per minute, we both expired the least 

 amount of carbonic acid at the lowest station, and the most at the 

 intermediate station, 7,090 feet high. The fluctuation between the 

 various stations was much the same for each of us respectively, 

 although the actual amount expired by each of us differed in a 

 marked degree. The mean relation for both of us respectively, 

 between the carbonic acid expired sitting and on the rocking-boards, 

 was found to be the same, and a trifle over twice the weight of the 

 carbonic acid expired sitting. 



The volume of air breathed while at work was decidedly less in my 

 case at Alta Yista than at the two lower stations, with the guide there 

 was a falling off in the air expired at Guajara. The mean volume of 

 air expired per minute, in all the experiments on the rocking-boards, 

 was for myself 11 "56 litres, and for the guide 13*95 litres. 



The general result obtained, with reference to this subject, was that 

 the relation between the volumes of air expired while sitting, and 

 while engaged with a regulated amount of muscular work, was the 

 same as the relation found to exist between the weights of carbonic 

 acid expired under such circumstances, and moreover that these pro- 



