546 Intelligence and Miscellaneous Articles. 
tion cylinders of the apparatus, and simultaneously the apparatus for 
analysis of the air, were at work, a weighed candle was lighted in 
the saloon from without, and, before the experiment terminated, 
again extinguisked from without and weighed. 
The carbonic acid formed by combustion of the candle must be 
partially contained in the air which had passed through the large 
gas-meter, and partly in that contained inthe saloon. ‘lhe carbonic 
acid in the air which had passed through the gas-meter was deter- 
mined by allowing a continually equal proportion (about 100 cubic 
centims. in a minute) of the current from the saloon to the gas-meter 
to bubble through lime-water, The carbonic acid of the air remain- 
ing in the saloon was determined, after mixing the different layers 
of air well together, by filling two or three vessels of 6 to 8 litres 
capacity, determining by lime-water, and calculating this upon the 
known capacity of the saloon. Itis only after these flasks have been 
filled that the saloon may be entered to take out the candle and 
weigh it. 
Since the air which passed into the gas-meter, and that which 
remains in the saloon, contained not only the carbonic acid formed 
in the experiment, but that already contained in the air as it passed 
into the saloon, the quantity of the carbonic acid of the air entering 
must be subtracted. ‘This is obtained from the experiment where 
the air which enters is withdrawn and investigated in just the same 
manner and the same quantity asthe emergent air. In this way the 
difference in the quantity of carbonic acid inside and outside is de- 
termined; and this ensures the exactitude of the determinations, 
because all constant errors of the method are thereby eliminated. Of 
course all the measurements are made with allowances for the ten- 
sion of aqueous vapour, of temperature, and pressure of the atmo- 
sphere. 
The author adduces some experiments which he made with stea- 
rine candles, and states his reasons for believing that, during an ex- 
periment in which more than four-fifths of the disengaged carbonic 
acid pass into the current between the saloon and the gas-meter, no 
greater errors than at most | or 2 per cent. are to be feared. Inas- 
much as the duration of experiments with men and animals can be 
extended to twelve or twenty-four hours, it is to be hoped that even 
greater accuracy may be attained. 
This is the first apparatus of its kind in which living is possible 
under normal conditions. Men can live in it just as well as in any 
well-ventilated room, and can move about, eat, and drink in the 
ordinary manner. By a moveable window in the door of the saloon, 
food and other articles can be supplied or taken out—just as, ina 
small room, provided the draught in the chimney is in order, a stove- 
door can be opened without admitting smoke. The observer out- 
side the saloon who has charge of the experiment does not by his 
respiration affect the result in the least; for the carbonic acid in the 
air passing into the saloon can be continually checked by one of 
the control apparatus, and can be allowed for.—Journal fiir Prakt. 
Chemie, vol. 1xxxii. p. 40. 
