702 
DE. E. SIMITH OX THE CHE:\nCAL 
September 14; and in almost every instance there was a fall in the 
quantity of carbonic acid on the follo™g morning (see Table). I 
passed a good night and was very well on April 20, 26, 30, iSIay 19, 
20, 24, June 4, 21, July 1, September 19, and November 4, and 
with equal uniformity the carbonic acid was increased (see Table). 
These may be appreciated by referring to Plate XXXIV . ; and it wiU 
also be observed that the changes were extremely well marked on 
May 18, 19, 20, 31, and June 1. With a large supper of meat there 
was an increase, but with a late supper with tea or cotfee there was a 
decrease. With much food taken during the preceding day, there 
was on May 31 an increase so large as to look like an error, whilst on 
the succeeding day, on which there was an unusual amount of exer- 
tion and deficiency of food, the decrease was equally great. 
The uniformity in these results is too striking to admit of theh being merely coinci- 
dences ; and whilst the general feeling of the system may not admit of very accuinte and 
minute definition, I believe that the following statement may be relied upon, tIz. that with 
much food on the preceding day, with good and long night s rest, and with a feeling of 
health and good spirits, the quantity of carbonic acid evolved before breakfast is greater, 
whilst it is lessened by the contrary conditions. The hour of supper and the natui-e of 
the food then taken will also vary the quantity. The mode by which tea and coffee act 
will be explained in a subsequent paper. I have not recorded many observations in refer- 
ence to the effects of spirituous liquors ; but whenever I had taken them at a late hour, 
it is recorded that the carbonic acid was lessened, but it is also stated that I had passed 
a restless night. The conditions favourable to the production of a large amount of car- 
bonic acid in the morning are such as have tended to induce profoimd and continued 
sleep, whilst in the adverse conditions there has been an miusual nocturnal acthit) of 
the respiration. This is agreeable to a priori reasonmg ; but I do not know that it has 
been hitherto demonstrated, and by it we may explain much of the remarkable differ- 
ences in the returns from day to day, and many diversities in the relathe quantities 
evolved by myself and Mr. Moul. 
y. Variations connected witli Season. 
Barkal* states that he excreted considerably more carbon in ufinter than in summer; 
and a similar observation was made by Vieeoedt; but their observations wei^ not made 
with such regularity and with such identity of external conditions as to elimmate the 
true effect of season. 
Mr. MiLNEEf, Surgeon to the Wakefield Prison, in a paper recently read before t le 
British Association, found, in an experience of ten years, and ffom 40,000 u eighings, 
that the prisoners, on the average, gained in weight from March or April to September, 
and lost weight during the other months of the year. 
* Annates de Chimie, 3 ser. vol. xxv. p. 165. 
t Sanitary Beyiew, 1858. 
