HANDBOOK FOR BIO-CHEMICAL LABORATORY. 79 



means of a pipette, small amounts of a concentrated solution 

 of chloride of lime or % per cent potassium permanganate 

 solution, drop by drop, and after each drop shake the mixture. 

 In the presence of indican the mixture turns blue, due to the 

 production of indigo blue. An excess of oxidizing reagent, 

 especially chloride of lime, interferes with the reaction, and 

 must therefore be avoided. If 2-3 c.c. of chloroform are 

 shaken with the blue solution, it will be colored blue by the 

 indigo blue formed. 



JAFFE'S Keaction (Crcatinin). Treat the solution with a 

 rather concentrated watery solution of picric acid and a few 

 drops of caustic potash solution. In the presence of creatinin 

 a red coloration, lasting several hours, is produced on warm- 

 ing. This color changes to yellow on the addition of acid. 

 Aceton and glucose give a similar reaction. 



v. JAKSCH'S Test (Glucose). Add in a test-tube containing 

 8-10 c.c. of the solution to be tested two knife-points of 

 phenyl hydrazin hydrochloride and three knife-points of 

 sodium acetate, and when the added salts do not dissolve on 

 warming, add more water. The mixture is heated in boiling 

 water for one hour. It is then poured into a beaker-glass of 

 cold water. In the presence of glucose a precipitate consist- 

 ing of groups of yellow needles of phenyl glucosazone is 

 formed. In doubtful cases determine the melting-point of 

 these yellow crystals to be 204-205 C. 



y. JAKSCH'S Test (Melanin). Add a few drops of a concen- 

 trated solution of ferric chloride to the liquid to be tested. In 

 the presence of melanin it turns gray, and on the addition 

 of more ferric chloride the precipitate, consisting of the color- 

 ing matter and the phosphates, is redissolved. 



Y. JAKSCH'S Test (IIC1 in Contents of Stomach). Paper moist- 

 ened with a saturated, watery solution, of benzQ^wrpurin 6 B 



