164 Butter Churning. [Sept., 



INFLUENCE OF THE IvlODE OF CHURNING ON THE HARD- 

 " NESS OR SOFTNESS OF BUTTER. 



BY PROF. JOHNSTON. 



Two facts are observed by the dairy maid in the preparation of 

 her butter, which are not without interest, either in a chemical 

 or in an economical point of view. 



First, the butter obtained on the same farm, and by the same 

 process, or method of churning, is almost every where observed to 

 be harder at one season of the year than at another. 



Second, the same milk under different management, or modes 

 of churning, yields butter of different degrees of hardness. 



The hardness of butter is a quality much prized; so much so, 

 that in some districts it is said to be artificially obtained by an 

 admixture of mutton or beef fat. Upon what, therefore, i!oe^ it 

 depend? Why is it greater at one season of the year than anoth- 

 er? Is there any thing in peculiar modes of churning wliich can 

 be supposed to diminish or increase it. 



Before we can answer these questions we must understand the 

 structure, so to speak, of milk, and the exact chemical composi- 

 tion of butter. 



Cows' milk consists of water to the extent of about 87 or 88 

 pounds in every hundred. This water holds in solution about 5 

 pounds of sugar and a little soda. In the saccharine solution there 

 are also dissolved 4 or 5 pounds of curd, which impart to it the 

 bluish-white opacity of skimmed milk. In this mixed solution, 

 again, there float a vast number of minute globules of semi-fluid 

 fat, each covered with a thin shell of a peculiar substance lesem- 

 bling curd, but, so far as our present knowledge goes, slightly 

 diflfeiing from it in composition. The curd, for instance, when 

 heated on polished silver, with a drop or two of a solution of 

 caustic pofash, causes a brownish black stain of sulphur upon the 

 silver; the substance which is supposed to form the envelope of 

 the globules gives no such stain. 



When milk is set asida for a time, and left undisturbed, these 

 globides of fat, with their coatings, rise to the surface of the milk, 

 and collect in the form of cream. 



When this cream is agitated for a length of time, in a churn or 

 otherwise, at a proper temperature, the thin coatings burst, or are 

 torn asunder, and the particles of half-liquid fat unite together and 

 form butter. This butter includes some of the thin envelopes of the 

 fat globules, with a little cuid and sugar, and a considerable pro- 

 portion of water. When churned, and well pressed, it consists of 



