1S47.] Butter Churning. 167 



air, which is continually renewed in the churn, and thus puts the 

 more tluid fat in conditions which are favorable to its change into 

 the more solid fat. And as the time of churning and the tem- 

 perature of the air and of the milk are rarely the same in any 

 two operations, even in the same season and in the same dairy, 

 there must necessarily be minute differences in the chemical con- 

 ditions, and therefore in the chemical results, though often unno- 

 ticed, of almost every churning. 



The above observations refer to the common churn worked 

 either by the hand or by other power, but many new forms of 

 churns have been lately introduced and recommended as capable 

 of producing the more speedy or more favorable results. 



Among these there are two ingenious and interesting forms well 

 spoken of by many, which may be supposed to owe a part of the 

 qualities ascribed to them to the peculiar chemical influence of 

 the air which I have above described. 



The one is Westori's Air Churn, which consists of a hollow 

 cylinder of zinc into which the milk or cream is put, and through 

 the bottom of which a current of air is driven by a small air pump. 

 This air throws the milk into violent agitation, and causes the 

 butter rapidly to separate. By this process the oxygen of the air 

 is more fully and with more frequent rencvvals brought into con- 

 tact with the milk, and thus a harder butter may be expected to 

 be in general produced. 



The other is a kind of churn, half-boxed in, invented and made 

 by Mr. Robinson of Lisburn, in which the cream is set in motion, 

 as in the barrel-churn, by a revolving wheel or beater — but in 

 passing from one side of the wheel to the other, the milk or cream 

 is made to traverse an uncovered part of the box, where it is 

 freely exposed to the air. In this part also, the butter, when it 

 begins to separate is arrested by a kind of grating, and is thus 

 prevented from again entering into the churn and becoming ex- 

 posed to the action of the beaters. If, therefore, the air really 

 has any influence in giving greater firmness to the butter in con- 

 sequence of a chemical change, such as I have described, this 

 form of chum, like that of Mr. Weston, seems well fitted to allow 

 it to have its full effect. 



The questions proposed at the commencement of this article, 

 seem therefore to be satisfactorily answered. It is granted that 

 chemical changes of various kinds take place in the digestive or- 

 gans, and perhaps even in the very udder of the cow. The fats 

 of the food are changed if necessary, into the two fats of the milk, 

 and these may no doubt exist in very different proportions in the 

 milk of different animals, and in that of the same animal at dif- 

 ferent times. The food, the temperature, the circumstances in 

 which the animal is placed may cause such differences — and in 



