THE URINE. 413 



temperature of the room, or, better, at a little higher temperature. 

 After this time test again with the bismuth test, and if the reac- 

 tion now gives negative results, then sugar was previously present. 

 But if the reaction continues to give positive results, then it shows 

 if the yeast is active the presence of other reducing, ferment- 

 able bodies. There may indeed be a possibility that the urine also 

 contains some sugar besides these bodies. This possibility is decided 

 by the following test : 



Phenylhydrazin Test. According to v. JAKSCH, this test is per- 

 formed in the following way : Add in a test-tube containing 8-10 

 c. c. of the urine two knife-points of phenylhydrazin hydrochloride 

 and three knife-points sodium acetate, and when the added salts 

 do not dissolve on warming add more water. The mixture is heated 

 in boiling water and kept there for one hour to avoid a confusion 

 with phenylhydrazin-glycuronic acid (v. JAKSCH and HIRSCHL). 

 It is then poured into a beaker of cold water. If the quantity of 

 sugar present is not too small, a yellow crystalline precipitate is now 

 obtained. If the precipitate appears amorphous, then on looking 

 at it under the microscope it appears partly as single and partly 

 as groups of yellow needles. If very little sugar is present, pour 

 the test into a conical glass and examine the sediment. In this 

 case at least a few phenylglucosazone crystals are found, while 

 the occurrence of smaller and larger yellow plates or highly-refrac- 

 tive brown globules do not show the presence of sugar. Accord- 

 ing to v. JAKSCH, this reaction is very reliable, and by it the 

 presence of 0.3 p. m. sugar can be detected (ROSENBERG, G-EYER). 

 A confounding with glycuronic acid is, according to HIKSCHL, not 

 to be apprehended when it is not heated in the water-bath for too 

 short a time (one hour). In doubtful cases where we wish to be 

 quite sure, prepare the crystals from a large quantity of urine, dis- 

 solve them on the filter by pouring over them hot alcohol, treat the 

 filtrate with water, and boil off the alcohol. If the characteristic 

 yellow crystalline needles, whose melting-point (204-205 C.) is 

 also determined, are now obtained, then this test is quite decisive. 



Polarization. The polariscopic investigation is of great value, 

 especially as in many cases it quickly differentiates between sugar 

 and other reducible, often laevo-gyrate substances. In the presence 

 of only very little sugar the value of this test depends on the delicacy 

 of the instrument and the dexterity of the observer; therefore this 

 method is perhaps inferior in most cases to the bismuth test or to 

 the phenylhydrazin test. 



If small quantities of sugar are to be isolated from the urine, 

 precipitate the urine first with sugar of lead, filter, precipitate the 

 filtrate with ammoniacal lead acetate, wash this precipitate with 

 water, decompose it with H 2 S when suspended in water, concentrate 

 the filtrate, treat it with strong alcohol until it is 80 vol. per cent, filter 



