32 THE SOLUBLE CONSTITUENTS. 



On warming with dilute nitric acid (sp. gr. 1-2) an energetic 

 action takes place, mucic acid, together with saccharic, oxalic, 

 and other acids being formed ; the mucic acid, which can be 

 separated by its relative insolubility, amounts to about 32 per 

 cent, of the weight of the milk-sugar. This is due to the galactose 

 portion of the milk-sugar. Strong nitric acid (sp. gr. 1-5) mixed 

 with sulphuric acid, to absorb the water formed in the reaction 

 gives rise to the formation of tri- and penta-nitrates ; both 

 these compounds have explosive properties. The penta-nitrate 

 is a constituent of certain high explosives. 



On heating with an excess of precipitated copper oxide gummy 

 acids are formed, such as galactinic and pec to -gal actinic acids, 

 compounds which are also formed from galactose. 



By oxidation with bromine lacto-bionic acid is formed, in 

 which the COH group is converted into COOH. Potassium 

 permanganate in acid solution oxidises it to carbonic acid, but 

 the reaction is not complete, not more than 80 per cent, of the 

 theoretical quantity of carbon dioxide being obtained. 



By heating with phenylhydrazine acetate two compounds are 

 formed ; one of these phenyl-lactosazone is sparingly soluble 

 in cold water, but in 80 to 90 parts of hot water, from which it 

 separates on cooling in fine yellow needles melting at 200 C. with 

 decomposition. It is also soluble in alcohol and ether ; the latter 

 solvent extracts it from aqueous solution. The second compound 

 is an anhydride of phenyl-lactosazone, and is almost insoluble 

 in hot water ; but can be crystallised from hot alcohol in yellow 

 needles which melt at 223 to 224 C. Milk-sugar is distinguished 

 from other sugars by its osazone forming an anhydride. 



By treating with strong cold hydrochloric acid the phenyl- 

 hydrazine groups are removed, and lactosone is formed. 



The relation between these compounds is shown by the following 

 formulse : 



Sugar. Osazone. Osonc, 



H-C-OH . H 0=0 



| C=N-N, I 



C I VTT HC=0 



/\\ Sp 



HO /* 



HC=N N 



The osone is readily reconverted into osazone by treatment 

 with phenylhydrazine acetate in the cold. 



By reduction with sodium amalgam a mixture of mannitol 

 and dulcitol, hexahydric alcohols of the formula CgH 14 6 , with 

 lactic acid and methyl, iso-propyl and hexyl alcohols is formed. 



