PERSPIRATION AND RESPIRATION. 200 
what would be the sense of duty of all who deem the physiology of assimila- 
tion important, when, on this occasion of making to the academy my first 
report of the apparatus now completed and tested, 1 express my most profound 
emotions of gratitude to his Majesty King Max II, of Bavaria, as the generous 
protector and intelligent promoter of the sciences. 
The whole apparatus was put up during the last winter. Since May I have 
occupied myself with testing it in every respect, and can now declare it com- 
plete and entirely satisfactory for the purposes proposed, which may be said 
also of all the methods of investigation employed in using it. ‘hat upon 
which the whole finally turned was the proof that the amounts of carbonie acid 
developed in the saloon of the apparatus could really be found again and de- 
termined with the requisite exactness, a test which in all previous respiratory 
apparatus has been wanting. After I had by various experiments ascertained 
all the influences which the apparatus and the methods exert upon the exact- 
ness of the results, I selected some stearine candles of good quality and deter- 
mined their amount of carbonic acid by elementary analysis. They yielded 
on the average, after three concurring experiments, ( Verbrennungen,) tor 
which the material had always been taken from a different candle, to 100 parts 
by weight, 291 parts by weight of carbonic acid, so that to one grain of stea- 
rine may be computed 1,484 cubic centimetres of carbonic acid, the weight of a 
litre of carbonic acid at 0° C. and 760 millimetres quicksilver pressure being 
reckoned at 1.987 grammes. If the suction-pumps of the apparatus and the 
aspirators for the analysis of the air were in operation at the same time, a 
weighed candle in the saloon was lighted from without and before the close 
of the experiment again extinguished from without and afterwards weighed, 
the carbonic acid formed by the burning of the candle must be partly in the 
air which has passed through the large gas-meter and partly in that which 
remains behind in the saloon. The amount of carbonic acid in the air which 
goes through the gas-meter is ascertained, as already mentioned, by passing 
through lime-water as long as the air flows and is measured, a constantly equal 
portion (say, 100 cubic centimetres per minute) drawn without interruption 
from the current which passes from the saloon to the gas-meter. The amount 
_ of carbonic acid which remains behind in the air of the saloon is determined 
in this manner: after a proper mixing of air-strata in the saloon by means of 
a fan put in motion from without, two or more flasks of six to eight litres, 
filled by the pump at the conductor leading off from the saloon, are tested with 
lime-water and an estimate made founded upon the known cubic measure of 
the saloon. Not until after these flasks are filled should the saloon be entered 
to take out and weigh the candle. As, however, the air which has passed 
through the gas-meter and that which has remained behind in the saloon con- 
tains not only the carbonic acid which arose from the burning of the candle in 
the saloon, but also that part which the air already contained when it entered 
the saloon from without, the amount of carbonic acid contained in the entering 
air must be deducted. This may be known from repeating the experiment by 
which the air flowing in is drawn off and examined in exactly the same man- 
ner and as nearly as possible the same quantity as that passing out. Only the 
difference, therefore, of the carbonic acid within and without is reckoned, and 
it is precisely this which makes the determinations exact, since all the constant 
errors of the system are thereby eliminated. , 
It is obvious that all measured quantities of air must be reduced, as regards 
tension of vapor, temperature and air-pressure, to the usual standard. 
I do not venture to ask the attention of the reader to all the necessary de- 
tails of the apparatus or of an experiment. I must reserve these and their 
justification to a more extended discussion in the papers of the technical com- 
mission, and take the liberty here only briefly to state, in addition, the results 
of three quantitative experiments. 
