380 Scientific Intelligence. — Chemistry. 



That portion or part of milk which is least influenced by variations 

 of food, he. in the cow is the caseous portion or curd. 



Four specimens of milk were obtained by the author from dairies 

 on different sides of Paris, and one other was taken from a cow and 

 brought immediately to him. Three hundred grammes of each of 

 these were warmed and treated with equal quantities of vinegar. 

 The curd of each being drained, and equally pressed between folds 

 of soft paper, furnished, namely, those from the dairies, each twen- 

 ty nine grammes of cheese, and that from the cow, thirty grammes. 



A second experiment, gave within a small fraction, the same re- 

 sult. 



Taking the quantity of this caseous matter as a type of the puiity 

 of milk, other equal portions of milk were mixed, each with an equal 

 weight of water, and treated in the same manner, when it was found 

 that the quantity of cheese was exactly one half. 



In a third experiment, the milk was diluted with twice its weight 

 of water, and the cheese was precisely one third. 



The last experiment was repeated, with the addition of sugar to 

 the milk and water ; when the cheese was extracted, the whey cau- 

 tiously evaporated to the consistency of extract, treated with boiling 

 alcohol, filtered and evaporated, the sugar which had been added was 

 recovered. 



To distinguish the milk which is adulterated with emulsion of al- 

 monds or of hemp-seed, one hundred and fifty grammes of pure 

 milk were united with one hundred and fifty grammes of emulsion of 

 sweet almonds, and the curd was separated by vinegar with the aid 

 of heat. Being well pressed, it weighed sixteen grammes y\. Then 

 another mixture was made, in the proportion of one hundred grains 

 of milk to two hundred of emulsion, and this furnished ten grammes 

 and eighteen decigrammes of curd, which it will be observed is pro- 

 portionate to the prior quantity. 



Besides, the curd or caseum of pure milk can be easily distinguish- 

 ed from that with the emulsion, by its consistency, and by the grease 

 vi^hich the latter yields when exposed for sometime to white paper. 



To prevent the milk from turning sour and curdling, as it is so apt 

 to do in the heat of summer, the milk men add a small quantity of 

 sub-carbonate of potash or soda, which saturating the acetic acid as 

 it forms, prevents the coagulation or separation of curd ; and some 

 of them practice this with so much success as to gain the reputation 

 of selling milk that never turns. Often when coagulation has taken 



