ajstd other phenomena oe respiration. 
707 
Thus it is proved indisputably that through long periods there is not a close corre- 
spondence, but, on the contrary, a wide difference in the relation between the degrees 
of temperature and the carbonic acid evolved ; and that as the season advances towards 
autumn, with the same temperature or even with a certain decline of it, the carbonic acid 
progi’essively falls to a minimum. It is also evident that both before and after the period 
of change, viz. June, the respiration retains a certain amount of uniformity ; and this at 
two different seasons will differ greatly, whilst it may be that the same temperature is 
found m both seasons. Thus my average quantities before July and after June respect- 
ively, in the four decades of temperature, differed as follows : 8-88 grs. and 8*21 grs., 8*69 
grs. and 7-43 grs.,^ 8-45 grs. and 7*44 grs., 8-35 grs. and 7T2 grs.-— differences of upwards 
of 1 of carbonic acid per minute in the three higher decades. Hence there is a want 
of uniformity in the progression of the decades, as before mentioned, due to the admix- 
ture of the results obtained in two seasons ; whilst Mr. Moul’s returns are more uniform, 
since they comprehend scarcely more than the early season. Further, it is interesting to 
know that at each of the seasons the movements of temperature keep in advance of the 
movements in the carbonic acid quantities. 
It now only remains to show that, even with sudden changes of temperature, there is 
not an exact relation between the temperature and the carbonic acid. The Table and 
Plate XXXIIL fig. 3, show this, fii-st, in the proportion of carbonic acid to each degree 
of temperature ; and secondly, the amount of diminution of carbonic acid with each 
increasmg degree of temperature. 
From the above we learn that as the temperatui'e increased the carbonic acid decreased 
m an increasing ratio, and consequently that the two did not move in parallel lines. 
This IS particularly well marked in my own case, in reference to both modes of inquiry, 
and in a yevj striking manner when the temperature exceeded 60°. Mr. Moul’s returns 
in the fii-st series correspond with mine, but in the second they manifest the influence of 
some other distui'bing cause. 
Hence it appears that any attempts to find one uniform relation between the carbonic 
acid and temperature, such as that published by Vierordt and Letellier, are exposed 
to serious error, and particularly if the inquiries, made upon different persons and in 
different seasons, are mixed together; and in reference to the influence of sudden 
c anges of temperature, the variations in the carbonic acid in my experiments are 
greater than -094 gr. per minute for each degree, as ascertained by Vierordt. It is 
also quite evident that the changes are due to vital conditions, and not simply to the 
physical action of heat upon the body and the inspired air. 
B. Barometric pressure. The relations between barometric pressure and the car- 
bonic acid expired are much less obvious than those of temperature ; and although my 
returns have a general correspondence with those of Vierordt, in showing that the 
relation is an inverse one, the rule is liable to many exceptions. Mr. Moul’s returns 
aie more amenable to the law than mine, for they continuously declined from month to 
month, whilst the barometer rose; but in my case the month of May was exceptional. 
Ihe lowest pressure was, however, in April, when the respiratory phenomena were very 
