704 
DE. E. SMITH ON THE CHEISnCAE 
there was a further decline in all the respiratory phenomena, until the tenmnation of 
his experiments at the middle of June. The extreme loss from season on the weekly 
averages, up to the middle of June, was 27 per cent, of carbonic acid, 2i per cent, of 
air, and 28 per cent, in the rate,— a degree of uniformity in the phenomena exceedingly 
striking. 
In Mr. Moul the greatest and most sudden changes occurred in the early spring. I 
had but little change in the spring, but there was a great dechne in summer, which 
continued until the autumn; and although Mr. Moul’s experiments ended before 
midsummer, the progression of his returns give us the right to infer that at the end of 
summer his quantities would also have been much reduced. Hence there is a close and 
significant relation between the actmty of the vital changes in Man and plants at those 
two periods, to which common experience has ever attached great importance, Hz. 
the spring and fall with their variations proceeding in yearly cycles. 
Having thus briefly stated the changes which occurred, it is now needful to determine 
to what elements in “ season” they are to be attributed. Of these, Temperature and 
Atmospheric Pressure are two of the most important, and have been im estigated by other 
observers. I have complete records of the former, and incomplete records of the latter. 
A. Temperature.— The returns prove that the relation between the quantity of carbonic 
acid evolved and the temperature of the air is an inverse one, as Viekoedt and others 
had established; but they also show that there is no absolute relation between a ghen 
temperature and the carbonic acid— a circumstance which has not been hitherto demon- 
strated. 
The effect of the first sudden elevation of temperature in April is strikingly coriobo- 
rative of the former assertion. Thus from March 31 to April 14, the tempemtuie 
gently and progressively fell from 66°*6 to 47°’6, and then it suddenly' rose 6 5 in one 
day, and became so high as 63°-6 in ten days, after which it rapidly feU. Until April 
14, with declining temperature, my returns show an increasing quantity of carbonic 
acid of more than 1 gr. per minute, ending in the large quantity of 9-| grs. per minute. 
On the contrary, Mr. Moul’s returns show a progressive decrease of more than 1 gr. per 
minute. The Table and Plate XXXIII. figs. 2 & 3, show the coordinated movement of 
the lines of temperature and carbonic acid during the period of the sudden increase of 
the former. 
Thus in my returns the carbonic acid suddenly decreased 1*3 gr. per minute, and 
almost as suddenly increased nearly 1 gr. per minute, the former correspondmg with 
the accession and the latter with the decline of temperature. :Mi-. Moul’s decrease was 
greater, and had its maximum on the day of the maximum temperature, whilst the 
increase was extremely great and rapid immediately after the temperature began to faU. 
After this period, to the beginning of J une, the curves of temperature and carbonic acid^ 
in Mr. Moul’s returns are opposed with tolerable uniformity ; and on the occuiience ot 
the second elevation of temperature at that period, there was again a sudden and tem- 
porary diminution of carbonic acid. 
The contrast of the monthly averages is of great interest. Thus — 
