FOOD PROTEINS 277 



to animal food products. The casein of milk also finds 

 some outlet for industrial purposes. When treated with 

 formaldehyde it yields an artificial horn much used for the 

 preparation of imitation tortoiseshell. Skim milk is treated 

 with caustic soda or carbonate of soda, the casein pre- 

 cipitated by acid, pressed, impregnated with formaldehyde, 

 and dried. The product is termed " galalith." It can be 

 distinguished from real tortoiseshell by the action of fuming 

 nitric acid (see J. C.S.I., 1909, 101). 



The utilization of the blood of animals, which is very 

 rich in protein, as a foodstuff has long been known, but has 

 met with a good deal of prejudice in this country. This 

 prejudice has arisen not merely from the objection to blood 

 as food, but also from the fact that such foods have been 

 particularly liable to putrefaction and hence to cause 

 poisoning. The shortage of all foodstuffs occasioned by 

 the European War did much to overcome this prejudice, 

 and there were considerable developments in the manufacture 

 of black pudding and similar preparations of animal blood. 

 The same circumstances made it necessary to consider more 

 seriously the possibilities of other butchers' offal as human 

 food, and resulted in new preparations of tinned animal 

 proteins being placed on the food market.. 



The author would like to record his opinion that by no 

 means the last word has been said on the question of drying 

 as a method for preserving animal food proteins. There is 

 much to be said for this method on every ground in theory, 

 and it is evidently an increasing success in practice. Dried 

 milk has been followed by dried eggs, and in view of the 

 success of the method when applied to fruits and vegetables, 

 there seems a prospect of better success in respect of dried 

 meats. After all, animal food proteins are chiefly lyophile 

 colloids, and though desiccation presents some practical 

 difficulties, the subsequent imbibition (assisted perhaps by 

 lyotrope influences) seems to be the ideal method for 

 restoring preserved protein to its original condition. 



In conclusion, it will be interesting to note in the sub- 

 joined table, the relative importance of the different sources 



