URINE. 37 



ylhydrazine-acetate solution furnished by the instructor, 1 and heat 

 on a boiling water-bath for one-half to three-quarters of an hour. 

 Allow the liquid to cool slowly and examine the crystals microscop- 

 ically (Plate III., opposite p. 24). 



The phenylhydrazine test has been so modified by Cipollina as to 

 be of use as a rapid clinical test. The directions for this test are 

 given in the next experiment. 



2. Cipollina's Test. Thoroughly mix 4 c.c. of urine, 5 drops 

 of phenylhydrazine (the base) and one-half c.c. of glacial acetic 

 acid in a test-tube. Heat the mixture for about one minute over 

 a low flame, shaking the tube continually to prevent loss of fluid 

 by bumping. Add 4-5 drops of potassium hydroxide or sodium 

 hydroxide (sp. gr. 1.16), being certain that the fluid in the test- 

 tube remains acid; heat the mixture again for a moment and then 

 cool the contents of the tube. Ordinarily the crystals form at 

 once, especially if the urine possesses a low specific gravity. If they 

 do not appear immediately allow the tube to stand at least 20 min- 

 utes before deciding upon the absence of sugar. 



Examine the crystals under the microscope and compare them 

 with those shown in Plate III., opposite page 24. 



3. Reduction Tests. To their aldehyde or ketone structure 

 many sugars owe the property of readily reducing the alkaline 

 solutions of the oxides of metals like copper, bismuth and mercury; 

 they also possess the property of reducing ammoniacal silver solu- 

 tions with the separation of metallic silver. Upon this property 

 of reduction the most widely used tests for sugars are based. 

 When whitish-blue cupric hydroxide in suspension in an alkaline 

 liquid is heated it is converted into insoluble black cupric oxide, but 

 if a reducing agent like certain sugars be present the cupric hy- 

 droxide is reduced to insoluble yellow cuprous hydroxide, which 

 in turn on further heating may be converted into brownish-red 

 or red cuprous oxide. These changes are indicated as follows : 



OH 



\ Cupric oxide 



\ (b 



OH 



Cu = + H 2 0. 



ric oxi 

 black). 



Cupric hydroxide 

 (whitish-blue) . 



solution is prepared by mixing one part by volume, in each case, of 

 glacial acetic acid, one part of water and two parts of phenylhydrazine (the 

 base). 



