420 



PEACTICAL PHYSIOLOGY 



the gas contained in it to the same as that of the gas in the 

 burette. After waiting two minutes the two menisci are again 

 brought to the same level, and the number of c.c. of N read off. 

 Another form of apparatus is that of Gerrard (Fig. 243). 



Fio. 242. Dupr^'s urea apparatus. 



FIG. 243. Gerrard's urea apparatus. 



For rapid clinical purposes quite satisfactory results may be 

 obtained by using the Doremus ureometer (Fig. 240), with side 

 tube for the urine. In using this 2 c.c. of urine are placed in the 

 small side tube and the main tube is filled with the hypobromite 

 solution. By turning the stopcock the urine is then allowed to run 

 very slowly into the hypobromite, when the nitrogen rises to and 

 collects at the top of the tube. When all effervescence has ceased the 

 apparatus is allowed to stand until it is cooled to room temperature, 

 when the graduation at which the meniscus stands is noted. This 



