SUGAR OF MILK. 755 



barytes, in grape sugar, is left to itself for some weeks (Peligot) . 

 The probable formula of anhydrous glucic acid is C 24 H 15 O 15 , or 

 it is formed from grape sugar by the loss of the elements of 

 water. Melassic acid is produced by the simultaneous action 

 of alkalies and heat upon grape sugar. With the concurrence 

 of air and a high temperature, alkalies convert sugar into formic 

 and sacchulmic acids. 



SUGAR OF MILK OR LACTJNE. 



Its formula,, in the crystallized state, is C 24 H 24 O 24 , or 

 C 24 H 19 O 19 + 5HO; by a heat of 248 (120 cent.) it loses 2 

 atoms, and by 302 (150 cent.) 5 atoms of water (Berzelius). 

 Sugar of milk is obtained by evaporating the whey of milk to 

 crystallization, and purifying the first product by animal charcoal 

 and a second crystallization. It forms white quadrangular prisms, 

 terminated by four-sided pyramids, which are semi-transparent, 

 and have the density 1.543. They are soluble in 5 or 6 parts 

 of cold water, and in 2 4 parts of boiling water, without forming 

 a syrup. The sweet taste of the crystals is very feeble when 

 they are applied directly to the tongue, but that of their solu- 

 tion is much more distinct. Sugar of milk is unalterable in 

 air, loses nothing at 2 1 2, and is insoluble in alcohol and ether. 

 Its solution dissolves hydrate of lime, and is converted by 

 dilute mineral acids into grape sugar, assuming then the 

 elements of 2 atoms of water. When milk is exposed to a 

 temperature of 95 to 104 ^55 to 40 cent.), it undergoes the 

 vinous fermentation, and is found afterwards to contain alcohol, 

 while its sugar disappears, but the latter is converted first into 

 grape sugar, probably under the influence of the free acid which 

 is formed and curdles the milk. Milk sugar forms two com- 

 pounds with oxide of lead, of which the formulae are C 24 H 19 O 19 

 + 5Pbl), andC 24 H 19 O 19 +10PbO (Berzelius). 



Mudc acid, C 12 H 8 O 14 + 2HO (Berzelius, Malaguti), is pro- 

 duced by the action of 4 parts of nitric acid, of density 1 .42, 

 diluted with I part of water, aided by heat, on 1 part of sugar 

 of milk ; a portion of the latter always passing at the same time 

 into oxalic acid. It is also formed by the action of nitric acid 

 on gum. Mucic acid is deposited on cooling, as a white crys-* 

 talline powder, of which s the taste is feebly acid, soluble in 



2 D D 2 



