936 PERSPIRATION AND RESPIRATION. 
door. On the side opposite to the door, two openings, one below and the other 
above, lead through two conducting pipes outside the small chamber into a 
single and larger pipe, through which the air flows towards that portion of the 
apparatus which performs the functions of a draught-chimney. ‘This portion, 
which may be placed in another apartment of the house than that in which 
the iron-chamber stands, consists of two suction-cylinders with hinge-valves, 
which may be equally moved by a strong clock-work, with any desired force, 
by means of a small steam apparatus. ‘The falling weight of the clock-work 
is at each moment wound up again as fast as it descends. In this way a con- 
stant current of air through the door of the iron-chamber to the suction-pumps 
can be maintained. The air cannot, however, reach the suction-pumps without 
passing through a measuring apparatus which is in constant operation. For 
this purpose 1 have chosen a gas-clock, or stationary gas-meter, of such dimen- 
sions that 3,000 English cubic feet per hour can be accurately measured by it. 
Tn order to examine a portion of the air which enters through the door and 
other apertures of the apparatus-room and passes out of the same by the united 
conductor to the gas-meter, and from the ascertained difference in the amount 
of water and carbonie acid, to be able to reckon the quantity which was added 
inside of the apparatus, two aspirators* are employed, which draw uniformly 
each a constantly equal portion of air. The water of the air is, after the 
known method, absorbed by sulphuric acid and weighed; the carbonic acid is 
ascertained by means of the air rising in small bubbles through a determinate 
quantity of lime-water of known strength, and the lime-water finally is exam- 
ined in regard to its amount of quicklime by treatment with diluted oxalic 
acid, exactly as I have described on another occasion. 
In order finally to be able to test the air which remains behind in the iron- 
chamber of the apparatus, a suction and force pump is placed in connexion 
with the pipe which conducts the air away, by the aid of which flasks holding 
six to eight litres ean be filled with air, which can be tested in regard to its 
amount of carbonic acid by lime-water. ‘The same pump serves also to ascer- 
tain, at suitable times during the experiment, the fluctuations of the carbonic 
acid in the air current. In addition to this, there is an arrangement which per- 
mits the making trials, of any number and extent, without suffering any loss 
of air for the measurement of the entire current. A flask is attached air-tight 
to the pump, the air of which flask is perfectly replaced by continued pumping 
with air from the conductor. The air forced from the flask is not allowed to 
escape, but is conducted by an India-rubber tube back again into the current 
which passes on to the gas-meter to a point, of course, where the determination 
of the carbonic acid cannot be affected by it; there is, therefore, a flask of air 
introduced below, and in its place a flask of air withdrawn from the apparatus. 
In order that the current of air may not discharge any water by evaporation 
from the large gas-meter, the air passes, before it enters the gas-meter, through 
a standing cylinder filled with pieces of pumice-stone, which are to be kept 
moist. Where the air passes out of the moistening apparatus a psychrometer 
is placed in the pipe in order to show the temperature and moisture with which 
it enters the gas-meter, and is measured. There are also in the conductor in 
front of the moistening apparatus a psychrometer and several places for at- 
taching tubes in order to take out air for experiment. 
After communicating the plan which I had projected to the president of the 
academy, Baron Von Liebig, and a few other associates in the same branch of 
science, I applied to the technical commission of the natural sciences of the 
academy. Upona report of this commission, accompanied by accurate esti- 
mates of costs, his Majesty granted out of his private purse 4,000 florins for 
the construction of the apparatus. I but follow the dictates of my heart, and 
* These aspirators are now replaced by two small pumps, which act both by suction and 
pressure. 
