246 



PHYSIOLOGY OF NUTRITION. 



glass cylinder, has been filled with water. Through the cork of 

 the generating vessel passes a glass tube provided with a glass 



stop-cock. This is 

 connected by means 

 of rubber tubing 

 with the graduated 

 glass tube in the 

 cylinder. The glass 

 stop-cock is pulled 

 but, and the com- 

 municating tubes 

 within the cylinder 

 are filled with water 

 by squeezing the 

 rubber ball while 

 keeping the clip 

 open. We now run 

 off the water 

 through the clip 

 till the bottom of 



^ ^_ ( the meniscus is ac- 



FIG. oi.-Azotometer. curately at the zero 



of the graduated 



tubes. After five minutes the stop-cock is again inserted, but so 

 turned that the generating vessel is left in communication with 

 the graduated tube. We wait for a little time, to see whether the 

 level of the water in the latter changes. If it does, the glass stop- 

 cock must again be taken out, and the water meniscus once more 

 brought to zero. 



The generating vessel is now removed from the cooling vessel. 

 By tilting it we slowly transfer the brominated soda to the fluid 

 under investigation, after running off through the clip 20-30 c.c. 

 of water. We then close the stop-cock, shake the generating 

 vessel vigorously, and again open the stop-cock so as to allow the 

 liberated Nitrogen to pass over into the graduated glass tube. 

 These operations are repeated several times. Then the generating 

 vessel is returned to the cooling cylinder, and Jeft in communica- 

 tion by means of the stop-cock with the graduated tube. After 

 about fifteen minutes, it will have assumed its original tempera- 

 ture, and we now open the clip, and bring the water to the same 

 level in the two communicating tubes. Finally we read off the 



