460 PHYSIOLOGICAL CHEMISTRY 



from pentose, since neither ferments, we may apply the Orcinol HC1 

 test of Bial, see page 458. To show lactose in the presence of glucose 

 the latter may first be removed by fermentation. 1 



EXPERIMENTS 



1. Mucic Acid Test. Treat 100 c.c. of the urine under examination with 

 20 c.c. 2 of concentrated nitric acid and evaporate the mixture in a broad, shallow 

 glass vessel, upon a boiling water -bath until the volume of the solution is only 

 about 20 c.c. At this point the fluid should be clear and a fine white precipitate 

 of mucic acid should separate. 



If the percentage of lactose in the urine is low it may be necessary 

 to cool the solution and permit it to stand for some time before the 

 precipitate will form. It is impossible to differentiate between galactose 

 and lactose by means of this test, but the reaction does serve to dif- 

 ferentiate these two sugars from all other reducing sugars. A sat- 

 isfactory differentiation between lactose and galactose in pure solution 

 may be made by means of Barfoed's test, page 29. This test is, 

 however, not suited for urine examination. To differentiate galactose 

 and lactose in urine use the Phloroglucinol-Hydrochloric Acid Reaction 

 of Tollens, see pages 36 and 461. 



2. Compound Test. Try the Nylander reaction. If positive try the phenyl- 

 hydrazine test. If negative (the lactosazone is not readily formed in urine) ap- 

 ply the fermentation test. If this test is also negative, differentiate between 

 lactose and pentose by Orcinol-HCl reaction (Bial) and mucic acid tests. 



GALACTOSE 



Galactose has occasionally been detected in the urine, and in par- 

 ticular in that of nursing infants afflicted with a deranged digestive 

 function. Lactose and galactose may be differentiated from other 

 reducing sugars which may be present in the urine by means of the 

 mucic acid test. This test simply consists in the production of mucic 

 acid through oxidation of the sugar with nitric acid. 



EXPERIMENTS 



i. Mucic Acid Test Treat 100 c.c. of the urine under examination with 

 20 c.c. 3 of concentrated nitric acid and evaporate the mixture hi a broad, shallow 

 glass vessel, upon a boiling water-bath, until the volume of the solution is only 

 20 c.c. At this point the fluid should be clear and a fine, white precipitate of 

 mucic acid should separate. 



1 Mathews: Sour. Am. Med. Ass'n, 75, 1568, 1920. 



2 If the specific gravity of the urine is 102001 over, it is necessary to use 25-35 c.c. of 

 nitric acid. Under these conditions the mixture should be evaporated until the remaining 

 volume is approximately equivalent to that of the nitric acid added. 



* If the specific gravity of the urine is 1020 or over it is necessary to use 25-35 c.c. of 

 nitric acid. Under these conditions the mixture should be evaporated until the remaining 

 volume is approximately equivalent to that of the nitric acid added. 



