ROUTINE OF AN EXPERIMENT WITH MAN. 99 



while the water is running into the small can, the water-meter is again 

 carefully weighed and the weight recorded. Having recorded the weight, 

 the water is again deflected into the large meter and what has accumulated 

 in the small can is carefully poured into the large meter through a funnel. 

 If the meter is nearly full, so that during the next period water will accu- 

 mulate and overflow the meter, it is emptied immediately after weighing 

 and while the small can is filling up. About 4 minutes is required to empty 

 the can completely. 



After it is emptied, it is again weighed, the water-current deflected from 

 the small can to the meter, and the water which has accumulated in the 

 small can carefully poured into the meter. All weights on the water-meter, 

 both of the empty can and the can at the end of each period, are checked 

 by two observers. 



ABSORBER TABLE. 



Shortly after the subject has entered the chamber and in many instances 

 before the sealing-in process has begun, the ventilating air-current is started 

 by starting the blower. The air passes through one set of purifiers during 

 this preliminary period, and as no measurements are made for this period 

 it is not necessary that the weights of the absorbers be previously known. 



All precautions are taken, however, so far as securing tightness in coup- 

 ling and installing them on the absorber system are concerned. During this 

 period the other set of absorbers is carefully weighed and made ready to 

 be put in place and tested and about 10 minutes before the experiment 

 proper begins the residual analyses are begun. The series of U-tubes, which 

 have previously been carefully weighed, are placed on small inclined racks 

 and are connected with the meter and also with the tube leading to the 

 mercury valve. The pet-cock which connects the return air-pipe with the 

 drying- tower and the gas-meter is then opened and the mercury reservoir 

 is lowered. The rate of flow of air through the U-tubes is regulated by a 

 screw pinch-cock on the rubber tube leading to the first U-tube. This rate 

 is so adjusted by means of the pinch-cock that about 3 liters of air per 

 minute will flow through the U-tubes, and as the pointer on the gas-meter 

 approaches 10 liters the mercury reservoir is raised at just such a point, 

 gained by experience, as will shut off the air-current when the total volume 

 registers 10 liters on the meter. The pet-cock in the pipe behind the meter 

 is then closed, the U-tubes disconnected, and a new set put in place. A 

 duplicate and sometimes a triplicate analysis is made. 



When the physical observer calls the time for the end of the period, the 

 switch which controls the motor is opened and the chemical assistant then 

 opens the rear valve of the new set of absorbers and closes the rear valve 

 of the old set, and likewise opens the front valve of the new set and closes 

 the front valve of the old set. As soon as the signal is given that the oxygen 



