118 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



2 per cent.; and B 20 cc. of A diluted to 200 cc., i.e., 0.2 per 

 cent. 



Experiment 7 is to be made only with solution B. 



10. Phenyl Hydrazine Test. Dissolve by shaking 2.5 g. 

 of phenyl hydrazine hydrochloride and 5 g. of sodium acetate 

 in 100 cc. of a 1 per cent, glucose solution or add about 2 cc. 

 of phenyl hydrazine, which has been previously dissolved in 

 acetic acid to acid reaction, filter if necessary, heat for three- 

 quarters of an hour upon the water-bath, and let cool gradu- 

 ally: crystalline mass composed of bright yellow needles of 

 phenyl glucosazone, C 18 H 22 N 4 4 . Filter these off, wash, dry a 

 small portion, and determine the melting-point. This should 

 be 204 to 205, if the compound is quite pure. If it is found 

 to be considerably lower, as is frequently the case with dia- 

 betic urine, or too high, which happens also sometimes, the 

 compound should be recrystallized from a mixture of equal 

 volumes of water and alcohol. Most of the sugars yield 

 osazones. These are usually characterized by their melting- 

 points. 



11. Reaction of Molisch. To ten drops or 0.5 cc. of the 

 sugar solutions (0.2 per cent, and 0.02 per cent.) add one 

 drop of an alcoholic or methyl alcoholic solution of a-naph- 

 thol, and let 1 cc. of pure concentrated sulphuric acid cau- 

 tiously run down the wall of the test-tube. At the surface 

 of contact of the two fluids a beautiful violet-red ring will 

 form, which, on shaking gently, increases in breadth and 

 intensity. The reaction of Molisch is a general one and is 

 common not only to the sugars, but to all carbohydrates. 



Detection of Glucose in Urine. 



Dissolve 4 g. of glucose in 100 cc. of a urine of moderate 

 concentration (specific gravity not less than 1017) : solution 

 A. Mix 10 cc. of solution A with 90 cc. of the same urine: 

 solution B. A part of the urine is kept for check experi- 



