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806 URINE.
alkaline during fermentation (alkaline fermentation), then the test
must be discarded. The vessel must be perfectly clean and strongly
heated before use. To make sure the urine may be boiled before fer-
mentation. 1
If a good polariscope is at hand it must not be forgotten to control
the results of the fermentation by determining the rotation before and
after fermentation. The phenylhydrazine test also, in many otherwise
doubtful cases, gives good service in testing urines for sugar.
Phenylhydrazine Test. Can be performed in the following manner:
20-25 cc. urine in a test-tube or in a beaker covered with a watch-glass
are treated with 1 gram phenylhydrazine hydrochloride and 2 grams
sodium acetate, and after solution of the salts it is warmed on the water-
bath for three-quarters of an hour. In the presence of sugar even dur-
ing the warming, a precipitate occurs, or in the presence of only a little
sugar, at least after the gradual cooling, a yellow, crystalline precipitate
forms. If the precipitate is very slight, it can be collected to advantage
by means of a centrifuge and investigated by aid of the microscope.
One finds at least a few phenylglucosazone crystals in the sediment
while the appearance of smaller or larger yellow platelets or strongly
refractive, brown globules is not indicative of sugar. In the presence
of large amounts of sugar in the urine a large quantity of the yellow
needles of phenylglucosazone or a mass of them are obtained.
This reaction is very reliable, and by it the presence of 0.03 per cent
sugar can be detected (Rosenfeld, Geyer 2
). In doubtful cases it is
necessary to investigate the nature of the precipitate. For this purpose
dissolve a large quantity of the crystals in hot alcohol, treat the filtrate
with water, and boil off the alcohol. Still better, the precipitate is
dissolved, according to Neuberg, in some pyridine, and again precipi-
tated as crystals by the addition of benzene, ligroin, or ether. If the
characteristic yellow crystalline needles, whose melting-point (204-
205° C.) may also be determined, are now obtained, then this test is
decisive for the presence of sugar. It must not be forgotten that fructose
gives the same osazone as glucose, and that a further investigation is
necessary in certain cases, and also that the impure crystals of phen-
ylducosazone have a much lower melting-point than the pure ones.
The following modification by A. Neumann is simple, practical, and at the
same time sufficiently delicate. 5 cc. of the urine are treated with 2 cc. of acetic
acid (30-per cent) saturated with sodium acetate, 2 drops of pure phenylhydrazine
1
On the performance of the fermentation test and certain sources of error, see
Salkow.sk i, Berlin, klin. Wochenschr., 1905 (Ewald-Festnummer), and Pfliiger, Pfliiger’s
Arch., 105 and 111.
2
Rosenfeld, Deutsch. med. Wochenschr., 1888; Geyer, cited from Roos, Zeitschr..
f. physiol. Chem., 15.
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