408 PHYSIOLOGICAL CHEMISTRY. 



betes by the very large quantity voided, by the pale color and high 

 specific gravity, and by its containing sugar. 



That the urine after the introduction of certain medicines or 

 poisonous bodies into the system contains reducing bodies, paired 

 glycuronic acids, which may be mistaken for sugar, has been men- 

 tioned in the previous pages. 



Properties of Grape-sugar. Grape-sugar crystallizes sometimes 

 with 1 mol. water of crystallization in warty masses or small leaves 

 or plates, and sometimes when free from water in needles. The 

 sugar containing water of crystallization melts even below 100 C. 

 and loses its water of crystallization at 110 C. The anhydrous 

 sugar melts at 146 C. and is converted into glucosan, C 6 H 10 6 , at 

 170 C. with the elimination of water. On strongly heating it is 

 converted into caramel and then decomposed. 



Grape-sugar is readily soluble in water. This solution, which 

 is not as sweet as a cane-sugar solution of the same strength, is 

 dextro-gyrate. The specific rotary power of a watery solution of 

 1-15$ anhydrous glucose at -|- 20 C. is indeed somewhat variable, 

 52.52-52.9 (LANDOLT), but the average may be considered as 

 -f- 52.6. Anhydrous glucose dissolves sparingly in cold, but more 

 freely in boiling, alcohol. 100 parts 85$ alcohol dissolves 1.94 

 parts glucose at -f- 17.5 C. and 21.7 parts at the boiling tempera- 

 ture (ANTHON). Glucose is insoluble in ether. If an alcoholic 

 caustic-alkali solution is added to an alcoholic solution of glucose, 

 an amorphous precipitate of insoluble saccharate is formed. On 

 warming the saccharate decomposes easily with the formation of a 

 yellow or brownish color which is the basis of the following re- 

 action. 



MOORE'S Test. If a glucose solution is treated with about of 

 its volume of caustic potash or soda and warmed, the solution be- 

 comes first yellow, then orange, yellowish brown, and lastly dark 

 brown. It has at the same time a faint odor of caramel, and this 

 odor is more pronounced on acidification. 



Glucose forms many crystallizable combinations with NaCl, of 

 which the easiest to obtain is (0 6 H 12 6 ) 8 .NaCl + H 2 0, which forms 

 large colorless six-sided double pyramids or rhomboids with 13.40$ 

 NaOl. 



Glucose in neutral or very faintly-acid (by an organic acid) 



