By Pror. Emerson REYNOLDS, M.D. 37 
are removed from the india-rubber tube, but are placed close at 
hand, and a piece of vulcanized tubing, five or six inches long, 
attached to the end of the glass tube C; suction is then applied by 
the mouth, when the curved end ¢c of the pipette is immersed in the 
hypobromite. The pipette is thus easily filled by suction with the 
re-agent up to the mark b. The forceps D are next applied to the 
connector, as shown, before the lips are withdrawn from the india- 
rubber tube attached to C; the suction tube may then be removed 
from c,as the liquid is retained in B by atmospheric pressure, 
provided D pinches the tube well. Having washed the end ¢ by 
pouring a little water over it, the cork carrying all its apparatus 
is securely inserted in the bottle A, the latter placed in the beaker 
T containing enough water to cover the cork when A is pressed 
down, and the tube E securely connected by the tightly-fitting 
india-rubber tube with 7. While connecting the generator and 
receiver a little water is necessarily expelled from the tube beyond 
H, but this water is thrown away and the dry two-ounce measure 
I then placed under the spout. 
Up to this point the hypobromite has not been allowed to come 
in contact with the urine, but now on removing the forceps D 
the hypobromite flows out from ¢ and rapidly mixes with the 
urine, the urea of which yields up its nitrogen gas with efferves- 
cence. As the gas evolved has no exit save through E it displaces 
from F its own volume of water, which falls into the vessel I, and 
can then be measured, when no more water is expelled. The 
effervescence ceases after five or ten minutes, according to the 
temperature. 
It is essential to good measurement that the pressure within 
the apparatus should be the same at the end as at the beginning of 
the experiment ; in order to secure this, the simple plan is adopted 
of placing a wedge under the board S at the end indicated, which 
is thus so tilted that the eye placed at a point a little below D, and 
looking immediately above the surface of the water in F, can just 
see the bend of the tube under H. When the pressure within and 
without has been thus equalized the amount of water expelled is 
the measure of the nitrogen evolved in A, for we may in a test 
of this kind neglect the extremely minute proportion of the 
nitrogen which has been dissolved by the water. 
