40 



Production of Butter. 



was of inferior quality, having all tbe characteristics of over- 

 churned butter. The reason why it is found requisite in practice 

 to churn milk and cream mixed at a higher temperature than 

 cream alone, arises from the fact that temperature has a marked 

 influence in promoting chemical changes. Reasons have already 

 been assigned why the lactic acid, formed in milk alone, must be 

 in a much more diluted form than that which will be found in 

 cream slightly acescent ; in order to compensate for this, a higher 

 temperature and longer time is required to produce the desired 

 effect. 



The preceding phenomena are in strict accordance with the 

 character of the churn used in the various districts where the 

 lacteal products of the cow are churned in different forms. Almost 

 invariably, certainly over the most extended area, the common 

 barrel churn is used in those districts where cream is churned alone. 

 By the barrel churn a large quantity of butter may be made from 

 cream, with a moderate degree of rapidity and at a comparatively 

 slight expenditure of labour, particularly as cream., when put 

 into the churn, is almost invariably in some degree acescent, 

 generally enough so for the purpose of obtaining the butter with- 

 out requiring to be further oxygenized. No practical benefit is 

 obtained by using cream quite sweet, as the increased labour 

 required in churning far more than counterbalances any slight 

 advantage which butter so made may derive for the purpose of 

 keeping. If proper care is taken in " making up " the butter 

 formed from cream slightly acescent at the time of churning, it 

 will maintain its freshness equal to that made from fresh cream ; 

 at the same time avoiding the risk of overchurning, Avhich will 

 always be much greater in churning fresh than sour cream. For 

 churning milk and cream the barrel churn is wholly inadequate, 

 the upright churn, or one with revolving dashers, being requisite 

 in order to sufficiently oxygenize the milk, for which purpose this 

 form of churn is well adapted, as there always remain suffi- 

 cient openings to admit the atmosphere ; whereas barrel churns 

 are hermetically sealed during the act of churning, the operation 

 having to be stopped occasionally for the purpose of opening a 

 vent-hole, which is occasionally done to allov/ the escape of the 

 gas evolved during the " breaking" of the cream. 



The American churn varies only from the ordinary square 

 churn with revolving dashers, in the circumstance that, instead of 

 the dashers being open, the back of the dasher is a fiat piece, 

 without any perforation, having raised edges and four transverse 

 pieces, dividing it something similar to the shelves of a bookcase. 

 When the dasher is turned round, the nests formed as described 

 convey and force into the milk or cream a quantity of the atmo- 

 sphere equivalent to the cubic contents of the hollow space, which 



