8ALTINO OF BDTTEl. 169 



the causes above mentioned, a liability to become 

 rancid and otfensive. When packed in tirkins, 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. Saltinfj 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 

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

 The liauid that runs off is a saturate<l solution of salt, 

 with all the magnesia and lime which were present 

 These arc much more soluble than the salt, and are 

 consequently dissolve*! first. 



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

 care in separating the buttermilk, cause the spoiling 

 of very great stmks of butter every year; a iar^e paflt 

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

 other coimnon purposes, simply because these poiati 

 have been n^iected. 



SECTION IIL or CAStnC AND 



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 Iodic acid- 

 15 



