410 PHYSIOLOGICAL CHEMISTRY. 



adapted for this purpose is obtained, according to NYLANDER'S 

 modification of ALMEN'S original test, by dissolving 4 grms. 

 Rochelle salt in 100 parts caustic soda of 10$ NaHO and adding 

 2 grms. bismuth subnitrate and digesting on the water-bath until 

 as much of the bismuth salt is dissolved as possible. If a glucose 

 solution is treated with about -fa vol., or with a larger quantity of 

 the solution when large quantities of sugar are present, and boiled 

 for a few minutes, the solution becomes first yellow, then yellowish 

 brown, and lastly nearly black, and after a time a black deposit of 

 bismuth (?) settles. 



On heating with PHENYLHYDRAZIN a grape-sugar solution 

 gives a precipitate consisting of fine yellow crystalline needles 

 which are nearly insoluble in water but soluble in boiling alcohol, 

 and which separate again on treating the alcoholic solution with 

 water. The crystalline precipitate consists of plienylglucosazom 

 (E. FISCHER) : C 6 H 12 6 + 2C 6 H 6 .N 2 H 3 = O^H^NA + 2H 2 + 2H. 

 This compound melts when pure at 204-205 C. 



Glucose is not precipitated by a lead-acetate solution, but is 

 almost completely precipitated by an ammoniacal basic lead-acetate 

 solution, On warming the precipitate becomes flesh-color or rose- 

 red. 



If a watery solution of grape-sugar is treated with BENZOYL- 

 CHLORIDE and an excess of caustic soda and shaken until the odor 

 of benzoylchloride has disappeared, a precipitate of benzoic-acid 

 ester of glycose will be produced which is insoluble in water or 

 alkali (BAUMANtf). 



If -J-l c. c. of a dilute watery solution of glucose is treated with 

 a few drops of a 15$ alcoholic solution of a-naphthol, the liquid is 

 colored a beautiful violet on the addition of 1-2 c. c. concentrated 

 sulphuric acid (MOLISCH). This reaction depends on the formation 

 of furfurol from the sugar by the action of the sulphuric acid. 



DIAZOBENZOL-SULPHONIC ACID gives with a sugar solution made alkaline 

 with a fixed alkali a red color gradually changing after 10-15 minutes 

 to violet (PENZOLDT and FISCHER). ORTHONITROPHENYL-PROPIOLIC ACID 

 yields indigo when boiled with a small quantity of sugar and sodium car- 

 bonate, and this is converted into indigo-white by an excess of sugar (BAEYER). 

 An alkaline solution of grape-sugar is colored deep red on being warmed with 

 a dilute solution of PICRIC ACID (BRANN). 



The detection of sugar in urine is ordinarily, in the presence of 

 not too little sugar, a very simple opperation. The presence of 



