



RESPIRATION CALORIMETER AND EXPERIMENTS. . 215 
carried out fails to fulfill its best purpose because these funda- 
mental principles are not yet understood. The most experi- 
enced investigators are fully persuaded that the best service 
which can be rendered to agriculture in this direction, for 
some time to come, must be in abstract experimental inquiries 
of the class to which these belong. 
THH APPARATUS. 
The name here used for the apparatus, ‘‘ respiration calorimeter,” is suggested 
by the fact that it is essentially a respiration apparatus with appliances for calor- 
imetric measurements. As a respiration apparatus it is similar in principle to 
that of Pettenkofer. The calorimeter is essentially a water calorimeter, that is 
to say, the heat evolved in the chamber is measured by a current of water. The 
appliances for measurement of both the respiratory products and the heat given 
off from the body differ in some important respects from those of any other 
apparatus with which we are familiar. 
The apparatus includes, first of all, a room or chamber in which the subject 
remains during the experiment. The chamber is furnished with a folding chair 
and table for the man’s use during the day, anda folding bed on which he sleeps 
at night. When the experiments involve muscular work a stationary bicycle, 
especially arranged for measuring the work done, is also introduced. Light 
enters through a window so that the occupant can see to read and write. Ven- 
tilation is provided by a current of fresh air, maintained by a pump specially 
devised for the purpose. This pump not only keeps up a constant current of 
air, but also measures its volume and withdraws samples regularly and accu- 
rately for analysis. The air is made to enter the chamber at the same tempera- 
ture as when it goes out, so that the quantities of heat brought in and carried 
out by this ventilating current are the same. Arrangements are provided for 
passing food and drink into the chamber and for removing the solid and liquid 
excreta., Arrangements described beyond prevent the passage of heat through 
the walls of the apparatus. The heat given off from the body is carried away 
by a current of cold water which passes through a series of pipes inside the 
chamber. Houses are warmed in winter by a current of water which is heated 
in the basement of the house, and passes through pipes and radiators in the 
different rooms. The heat thus radiated from the water into the room keeps 
the air of the latter at the desired temperature. In like manner the house might 
be cooled in summer by a current of cold water. In this case the radiators 
would become absorbers. ‘The heat would be taken up from the air of the room 
by the cold water and carried away. Exactly this is done by the absorbers 
inside the chamber of the respiration calorimeter. By regulating the tempera- 
ture of this water current as it enters, and also its rate of flow, it is possible to 
carry away the heat just as fast as it is generated, and thus maintain a constant 
temperature inside the chamber. The amount of the outgoing water and its 
temperature are measured, thus determining the heat carried away. 
Inasmuch as the technical details of the apparatus and methods are to be 
given elsewhere a brief account will suffice here. ‘I’his may include a few words 
regarding the arrangements for measuring the temperature of the air inside the 
