SALTING OF BUTTLE. 169 



the causes above mentioned, a liability to become 

 rancid and offensive. When packed in firkins, it will 

 be rancid next to their sides and tops; will be injured 

 to a greater or less depth, as the air may have obtain- 

 ed access. Salting will partially overcome the ten- 

 dency to spoil, but not entirely, unless the butter is 

 made so salt as to be hardly eatable. Another reason 

 for much of the poor butter, which is unfortunately 

 too common, is to be found in the impure quality of 

 the salt used. This should not contain any magnesia 

 or lime, as both injure the butter; they give it a bit- 

 ter taste, and prevent its keeping for any length of 

 time. Prof. Johnston mentions a simple method of 

 freeing common salt from these impurities. It is to 

 add to 30 lbs. of salt about 2 qts. of boiling water, 

 stirring the whole thoroughly now and then, and al- 

 lowing it to stand for two hours or more. It may be 

 afterward hung up in a bag, and allowed to drain. 

 The liquid that runs off is 9 saturated solution of salt, 

 with all the magnesia and lime which were present. 

 These are much more soluble than the salt, and are 

 consequently dissolved first. 



Want of caution as to the quality of salt used, and of 

 care in separating the buttermilk, cause the spoiling 

 of very great stocks of butter every year; a large part 

 of that sent to Europe is sold for soap grease, and for 

 other common purposes, simply because these points 

 have been neglected. 



SECTION III, OF CASEIN AND CHEESE. 



Cheese is made from the casein of milk: this casein 

 or curd, is separated from the whey by means of ren- 

 net; the same thing may be done by small quantities 

 of acids, as acetic or hydrochloric acid; and if the 

 milk be allowed to stand long, it will be done na- 

 turally by the formation of what is called lactic acid 

 15 



