CASEOUS MATTER. 215 



Alcohol speedily precipitates the caseous matter under 

 the form of fine molecules, at the bottom of the vessel. 



Very acid plants and the flowers of some vegetables, 

 such as the artichoke and the thistle, curdle milk : these 

 are usually employed by infusing them in cold water, and 

 their action upon warm milk is very powerful. 



The substance however which is most generally used is 

 a portion of the milk curd which is found in the stomachs 

 of young calves that have been killed before they were 

 weaned. The use which is made of this substance has 

 given it the name of rennet* This substance is prepared 

 for use in the following manner. The membrane of the 

 stomach of a young and newly killed animal is opened, and 

 the coagulated milk is taken out, washed with cold water, 

 dried with a linen cloth, salted, and returned into the mem- 

 brane ; this is suspended in a dry place that the rennet 

 may be freed from moisture : the rennet may afterwards be 

 used by mixing a little of it in milk, and then throwing the 

 liquid into the milk which is to be curdled. 



The quantity of rennet necessary to be employed at any 

 one time for the same measure of milk, varies very much 

 according to the quality of the milk and the temperature of 

 the atmosphere : thick, rich milk, which has not been skim- 

 med, requires more than that which is thin, or from which 

 the cream has been removed. In winter it is often neces- 

 sary to warm milk slightly to make it curdle. 



As soon as the milk curdles it is allowed to remain un- 

 disturbed in a cool place, in order that the curd may ac- 

 quire some degree of firmness, and that all the particles may 

 become united in one mass, and likewise to allow all the 

 whey to drain off: it is then dipped up with a skimmer 

 and put into a vat or bucket of osier, through which the 

 whey contained in the curd can escape freely. As soon 

 as the curd has acquired a certain degree of consistency 

 in the willow baskets, it is removed into vats of earthen- 

 ware having small holes in the bottom ; through these the 

 whey still continues to drop, and the curd gradually in- 

 creases in density. Curd, from its first formation to the 

 period of which we are now speaking, forms an article of 

 diet equally healthy and agreeable, and furnishes a great 



rin this country the term is applied to the dried and salted stom- 

 of the calf, a piece of which is employed to produce the coagula- 

 tion required. — Tr.] 



