53 



Place in the bottle 20 cc. of fresh hypobromite solution. 

 Fill the little test-tube with urine to the 4 cc. mark and care- 

 fully lower it into the bottle so as not to spill any of its con- 

 tents. Hook the bent overflow tube over a graduate and re- 

 moving the little rubber cap, fill with water the graduated 

 jar to .slightly above zero. Put on the cap far enough to 

 depress the surface of the water exactly to zero. See that 

 all of the joints are tight, and tip the bottle .so that the urine 

 slowly flows out, and shake it occa.sionally. When the ac- 

 tion appears to be at an end, pour into the graduate water 

 enough to reach above the opening of the overflow tube, in 

 order that cooling of the gas evolved, which is at first quite 

 warm, maj' not draw air into the apparatus. Let it stand 

 for a few minutes to cool. In half an hour lower the end of 

 the overflow tube to the level of the water in the cylinder 

 and read off the percentage of urea. This multiplied by 

 4.55 will give grains per fluid ounce, at a room temperature 

 of 21° C. (70° F.). 



252.- Make another test with the Doremus ureometor. 

 After filling the long arm and bend of the ureometer with 

 the hypobromite solution and thoroughly washed the pipette, 

 draw up exactly i cc. of urine and pass the pipette through 

 the bulb of the ureometer as far as it will go in the bend. 

 Compress the bulb of the pipette gently and steadily. The 

 urine will rise through the h3'pobroniite, and th2 urea in- 

 stantly decompose, giving off nitrogen gas. Withdraw 

 the pipette after the urine has been expelled, taking care 

 not to press the bulb hard enough to drive the air out with 

 the urine, and read the volume of gas, after allowing the 

 froth to subside. 



The CO2 resulting from the decomposition of the urea 

 is absorbed by the excess of soda in the hypobromite .solu- 

 tion, and nitrogen is evolved, o.i gram of urea yields 

 35.4 cc. of nitrogen. 



253. A man excretes 38 to 40 grams of urea daily ; a 



