HUMANISED MILK. 343 



albumin is changed, so that practically all of it is precipitated 

 along with the casein on the addition of salts, e.y., magnesium 

 sulphate. The casein, when precipitated from sterilised or 

 Pasteurised milk, is much more finely divided than that from 

 fresh milk. It is therefore probably more easily digested, 

 especially by young children. 



The chief difference between human milk and cows' milk is 

 in the character of the curd which is produced by rennet or 

 the gastric juice of young children ; the former yields a finely 

 divided mass, while the latter gives a closely adherent, heavy 

 clot, probably much less easily digested. This difference is 

 ascribed, not to a difference in the casein or even in its 

 amount, but to the different amounts of calcium present. 

 Human milk contains about O03 % CaO, while in cows' milk 

 there is about 0-16% CaO. It has been shown that the coagu- 

 lation of casein by rennet is dependent upon the presence of 

 calcium compounds and that in their absence no coagulation 

 occurs." Hence it has been proposed to render cows' milk 

 more like human milk, and therefore more suitable for feeding 

 infants, by the removal of a portion of the lime ("humanised 

 milk"). This, it is said, can be done by adding about O5% of 

 sodium citrate. The addition of lime water, it may be noted, 

 though it delays curdling by reason of its alkalinity, would not 

 improve the character of the curd when it is formed. Another 

 somewhat curious fact is that cows' milk contains more lime 

 than an equal volume of lime water (which contains about 

 0'13%), so that the idea that the addition of lime water aids in 

 supplying materials for the formation of bone is founded on a, 

 misconception. 



Other Methods of Preserving Milk. As already stated, it 

 is possible to prevent the growth of micro-organisms in milk 

 by the addition of antiseptics, and this is often practised, 

 especially in hot weather, when their growth is apt to be very 

 rapid. The chief antiseptics employed in preserving milk, 

 butter, and cream are 



Boric acid or borax, H H BO 3 o* Na. 2 B 4 O 7 .10H. 2 O. 



Salicylic acid, C (i H 4 (OH)COOH. 



Formaldehyde, H 2 CO, generally as "Formalin." 



* Avthns anil Pages, 1890. 



