The Students' Guide in Quantitative Analysis - Free Ebooks Library

ANALYSIS OF URINE. 11$
C. — Hcintz and Ragskys Method.
First determine ammonia by precipitation with PtCl^.
Heat 2 to 5 c. c. with equal vol. H^SO^ in a covered cap-
sule to i8o°-2oo°. Cool, dilute with water, filter, and de-
termine NH. formed by PtCU Calci'Iate both amounts for
loo c. c, and take the difference ; this multiplied by 0. 13425
gives per cent, of urea.
Results very accurate.
D.—AfijoJuis Method.
See "American Chemist," V. 431.
Provide the following apparatus :
(i) A glass tube 30 cm. long, subdivided into 30 equal
parts, whose aggregate volume is 55
tube is drawn out like a Mohr's burette.
c. c. The end of the
(2) A wide-mouthed gas bottle of 60 c. c. capacity.
(3) A test tube of 10 c. c. capacity, and long enough to
be slightly inclined when introduced into the gas bottle.
The principle of the process is based upon the following
equation :
2(CON2H0+3(CaBr2O,)=3CaBrs-f-2CO3+N4
To make the hypobromite solution take loogrms. NaHO,
250 c. c. H2O, and add 25 c. c. bromine ; agitate and set
aside for use.
Process : Into a glass cylinder containing water the tube
(r) is depressed till the zero mark and surface of water
coincide, 15 c. c. hypobromite solution (100 grms. NaHO,
250 c. c. H2O, 25 c. c. Br) are placed in (2) and the test-
tube containing the urine is introduced carefully to avoid
spilling its contents. The flask is closed by a perforated