CHAPTER IV. 



THE MANUFACTURE OF BUTTER. 



47. The Different Methods in which Butter is Made. Butter is 

 the most important product of milk. As usually manufactured, 

 fresh butter contains about 83 to 84 per cent of milk-fat, 14 to 15 

 per cent of water, and 1*2 to 2 '2 per cent of the other constituents 

 of milk. The percentage of the single chief constituents of the iion- 

 fatty total solids of butter, if not exactly, is approximately the same 

 as in milk. Hitherto it has not been possible to obtain, in the form 

 of butter, all the fat which any quantity of milk contains. 



In the preparation of butter the object aimed at is to solidify 

 the largest possible number of fatty globules in the milk, and then 

 to incorporate them. This has been hitherto, and still is effected, 

 by churning, which consists in shaking violently the fatty glo- 

 bules, and by this violent motion bringing them into intimate con- 

 tact with one another. Although butter can be obtained by direct 

 churning of the milk, an easier and preferable way is to collect 

 the larger portion of the fatty globules by allowing the milk to 

 be divided into two layers, the top layer, which contains as much 

 fat as possible, constituting the cream, and the lower layer, the skim 

 milk, which may be five to six times deeper than the top layer, 

 and contains the least possible amount of fat. The skim milk is 

 separated and the cream is churned. This separation was effected 

 up to the year 1877 by setting the milk in suitable vessels so as to 

 permit it to collect. It was left for from 12 to 48 hours, and even 

 longer, until the greater part of the fatty globules, owing to their 

 light specific gravity, collected on the top, and formed a layer easily 

 recognizable by the eye. In this way the milk was divided by a 

 sharp line into two layers, the skim milk and the cream. Since the 

 year 1877 centrifugal force has been employed for the separation of 

 cream from milk, and the use of this method has extended every 

 year since. There are thus two methods of obtaining cream, the 

 old and the new. 



It is perhaps not superfluous to notice that cream and butter are not 



100 



