20 THE CHEMISTRY OF CATTLE FEEDING 



It reacts with barium hydrate, forming barium bromide 

 and a mixture of two sugars called respectively a and /3 

 acrose. 



2C 3 H 4 OBr 2 -f 2Ba(OH) 2 -> 2BaBr 2 + C 6 H 12 O 6 



These two substances can be separated by conversion into 

 osazones with phenylhydrazine. The a-acrosazone is identical 

 with the corresponding compound obtained from fructose 

 and can be converted into that substance as previously 

 shown (p. 1 8). 



The dextrorotatory glucose ([a] D = 52-6), also called 

 dextrose or grape sugar, is of common occurrence in vegetable 

 products. It enters largely into the composition of grapes, 

 apples, and other fruits, and it forms the chief nutrient of 

 the common root crops, swedes, turnips, and mangels. It 

 occurs also in honey, and is a constituent of urine in certain 

 forms of diabetes. 



The commercial product obtained by acid hydrolysis of 

 starch, and sold under the name of glucose or saccharum, 

 contains about 60 per cent, of actual glucose, together with 

 some mucilaginous substances. It is largely employed in 

 brewing and confectionery, and it may also be used in cattle 

 feeding. 



Fructose, fruit sugar, or laevulose is also found in honey, 

 in fruits, and other vegetable products,, but it is not so common 

 as glucose. Though definitely laevorotatory in its action on 

 polarised light, [a] D = 7i'4j it has unfortunately been 

 called ^/-fructose because it>was prepared from ^/-glucose and 

 ^-mannose. When required in quantity, it is usually pro- 

 duced by acid hydrolysis of the inulin obtained from dahlia 

 roots. 



Bihexoses. The elementary composition of the bihexose 

 sugars is represented by the empirical formula Ci 2 H 22 O 11 . 

 They appear to be anhydro-compounds of the hexoses, but 

 they have not yet been synthetically prepared, and the exact 

 nature of the union is still obscure. 



The reverse process, i.e. splitting up the bihexose sugars 



