98 CALORIMETERS FOR STUDYING RESPIRATORY EXCHANGE, ETC. 



current is started and the whole apparatus is adjusted to bring away the 

 heat prior to the entrance of the man. The rate of flow with the chair 

 calorimeter is not far from 350 cubic centimeters per minute with a resting 

 man. The proper mixture of cold and warm water is made, so that the 

 electric reheater can be controlled readily by the resistance in series with it. 

 Care is taken not to allow the water to enter the chamber below the dew- 

 point and thus avoid the condensation of moisture on the absorbers. The 

 thermal junctions indicate the temperature differences in the walls and the 

 different sections are heated or cooled as is necessary until the whole system 

 is brought as near thermal equilibrium as possible. 



After the man enters, the lamp is removed and the water-current is so 

 varied, if necessary, and the heating and cooling of the various parts so 

 adjusted as to again secure temperature equilibrium of all parts. When the 

 amount of heat brought away by the water-current exactly compensates 

 that generated by the subject, when the thermal-junction elements in the 

 walls indicate a or very small deflection, when the resistance thermometers 

 indicate a constant temperature of the air inside the chamber and the walls 

 of the chamber, the experiment proper is ready to begin. 



The physical observer keeps the chemical assistant thoroughly informed 

 as to the probable time for the beginning of the experiment, so that there 

 will be ample time for making the residual analyses of the air. After these 

 analyses have been made and the experiment is about to begin, the observer 

 at the table calls the time on the exact minute, at which time the blower is 

 stopped and the purifying system changed. The physical observer takes 

 the temperatures of the wall and air by the electric-resistance thermometers, 

 reads the mercury thermometers, records the rectal thermometer, and at the 

 exact moment of beginning the experiment the current of water which has 

 previously been running into the drain is deflected into the water-meter. 

 At the end of the period this routine is varied only in that the water-cur- 

 rent is deflected from the water-meter into a small can holding about 4 

 liters, into which the water flows while the meter is being weighed. 



MANIPULATION OF THE WATER-METER. 



The rate of flow of water through the apparatus is determined before the 

 experiment begins. This is done by deflecting the water for a certain 

 number of seconds into a graduate or by deflecting it into the small can and 

 weighing the water thus collected. The water is then directed into the 

 drain during the preliminary period. Meanwhile the main valve at the 

 bottom of the water-meter is opened, such water as has accumulated from 

 tests in preceding experiments is allowed to run out, and the valve is closed 

 after the can is empty. The meter is then carefully balanced on the scales 

 and the weight is recorded. At the beginning of the experiment the water 

 is deflected from the drain into the meter. At the end of the period, 



