200 SUGAR OF MILK. MYCOSE. 



tartaric, and racemic acids ; boiled with it, it yields 

 oxalic acid. 



Octacetyl-canesugar, C 12 H 14 (O.C 2 H 3 0) 8 3 . Is pro- 

 duced when cane-sugar is heated with an excess of 

 acetic anhydride to 160. White, amorphous mass, 

 insoluble in water and acetic acid. A very similar 

 compound of the same composition is also produced 

 when grape-sugar is heated for a long time at 160, 

 with a large excess of acetic anhydride. 



7. Sugar of Milk. 



C 12 H 22 11 



Occurrence. Only in the milk of animals. 



Preparation. The casein of the milk is precipitated 

 by heating with a dilute acid, or, better, with rennet 

 (calves' stomachs), and the yellow liquid (whey) evapo- 

 rated to syrupy consistence. On standing for a length 

 of time in a cool place, the sugar of milk crystallizes 

 out. It is purified by repeated recrystallization. 



Properties. Colorless, translucent, four-sided prisms, 

 possessing but a slightly sweet taste ; is slowly soluble 

 in water, and crystallizes even from a saturated solu- 

 tion but slowly. But slightly soluble in alcohol. The 

 aqueous solution rotates the plane of polarization to 

 the right, and reduces alkaline solutions of copper and 

 silver. When heated with dilute acids, or left in con- 

 tact with yeast, it is resolved into lactose and another 

 variety of sugar, probably grape-sugar. When heated 

 with nitric acid, it yields mucic, saccharic, tartaric, 

 racemic acids, and, as final product, oxalic acid. 

 Heated with acetic anhydride, it yields an ether 

 similar to that formed from cane-sugar under the same 

 circumstances. 



8. Mycose ( Trehalose.) 

 C"H 22 O n + 2H 2 0. 



In ergot of rye, several other fungi and trehala- 

 manna, an article of food used in the East. Lustrous, 



