292 SCIENCE AND PRACTICE OF DAIRYING. 



its high price, which is due to the fact that it is only found in the 

 milk of mammals. It may be described as of rare occurrence in 

 nature; furthermore, it is only obtained from one mammal, namely, 

 from the milk of the cow, while on the other hand the raw material 

 for the manufacture of cane- and beetroot-sugar is very abundant. 

 Milk-sugar differs from cane and beetroot, as has already been 

 pointed out, chiefly by its much weaker sweetening power, and by 

 the fact that it is much less soluble in water than the other forms 

 of sugar, and forms saturated solutions which are not of the nature 

 of syrups, but are of a limpid consistency. These properties render 

 it very valuable for many purposes, especially for medicinal use. 

 It is used in medicine in the preparation of homoeopathic medicines, 

 for the purpose of diluting saccharine or powerfully acting drugs, 

 which have to be taken only in very small quantities, and also as 

 an addition to milk to be employed for the feeding of children 

 during the period of infancy. It has further been used for the 

 purpose of adulterating wine, and in certain purely technical arts. 

 On the whole, its use is comparatively limited, and can scarcely be 

 expected to be much extended. In the ordinary method of the 

 manufacture of milk into cheese, about 85 per cent of the entire 

 amount of the milk-sugar in the milk passes into the whey, with 

 the result that this latter contains on an average about 4'S per cent 

 of milk-sugar. 



Whey is the raw material from which milk-sugar is prepared. 

 Its condition, the lactic and acetic acids it contains, its albu- 

 minoids and mineral salts, and especially the alkali salts, increase 

 the difficulty of separating the milk-sugar. By the action of the 

 acids and the mineral salts, a portion of the milk-sugar is carried 

 away in the process of crystallization, and is thus lost. By the 

 addition of milk of lime the acids may be fixed, but the alkali salts 

 cannot be removed, and what is gained on the one hand is lost on 

 the other, by the formation of a compound of sugar and chalk. 

 And since the albuminoids which are present impede the crystalli- 

 zation of the sugar, even under the most favourable conditions, it is 

 not easy to obtain more than 66 per cent of the milk-sugar in the 

 whey. In the preparation of beetroot -sugar, 80 per cent of that 

 originally present in the raw material is easily obtained, while in 

 the preparation of cane-sugar a still larger yield is obtained. Thus, 

 owing to the fact that only a comparatively small portion of saleable 

 sugar can be recovered from the milk-sugar in the whey, and that 



