66 ORGANIC CONSTITUENTS. 



acetic or citric acid, sugar of milk becomes converted into sugar 

 of grapes. By nitric acid it is decomposed into mucic/ oxalic, 

 saccharic, and carbonic acids. 



On the addition of casein, animal membrane, diastase, &c. 

 to a solution of sugar of milk, lactic acid is formed and the 

 fluid begins to ferment. 



Crystals of sugar of milk may be represented by the formula 

 Cj2 Hj2 Oj„. At a temperature of 212° the crystals lose 11 '95, 

 or tAvo equivalents of water. Consequently the formida for 

 anhydi'ous sugar of milk is C^JI^fi^^. 



j3. Diabetic sugar exists in the blood and urine, and occa- 

 sionally also in the sweat" of persons suffering from diabetes. 



It may be obtained by adding basic acetate of lead to the 

 urine, filtering, precipitating any excess of lead by sulphm'etted 

 hydrogen, evaporating, extracting the syrupy residue with 

 alcohol, and allowing the alcoholic solution to crystallize. It 

 requires several crystallizations to obtain the sugar in a state of 

 purity. Diabetic sugar usually crystallizes in wart-like knots, or 

 plumose groups, of minute, rhombic, transparent crystals. It is 

 white, devoid of odour; in sweetness and in solubilitj^ in water^ 

 it ranks between cane sugar and sugar of milk. It is more 

 soluble in dilute alcohol than sugar of milk, but is insoluble in 

 absolute alcohol and ether. 



Diabetic sugar in a crystalline state is represented by 

 the formula C,, H,, O,. : in this condition it contains 



1 '2 14 14'^ 



two equivalents, or 9|j of water, so that its correct formula is 

 Cj„ H,„ 0,„-|-2H0. It is identical in its chemical compo- 

 sition with sugar of grapes. 



Diabetic sugar forms a beautiful crystallizable compound 

 with chloride of sodium. On saturating diabetic urine with 

 common salt, and lea\ing it to spontaneous evaporation, 

 crystals three fom^ths of an inch in diameter may be ob- 

 tained. They are not very regular in their form, but most of 

 them are six-sided double pyramids. These crystals are hard, 

 easily pulverizable, transparent, of a combined saltish and sac- 



' It is worthy of remark that sugar from different sorts of milk yields varying quan- 

 tities of mueic acid. 



^ A. case in which sugar was detected in the sweat of a diahetic patient is recorded 

 by Nasse, Rhein. Corresp. Blatt. 1842. Nr. 6. 



^ Simon found that one part of diabetic sugar dissolved in TS of water at 53°. 



