34 



globules are growing smaller, hence cows in an advanced stage of lac- 

 tation produce milk which separates very slowly. Finally, a sudden 

 chilling of the milk immediately after milking and keeping it at a tem- 

 perature of 40" F. aids in a thorough separation of the cream. 



Shallow Selling. — This old method has long been discarded by those 

 who understood moderii dairy principles. Its chief objection is its 

 inconvenience, and the diiiiculty of securing a complete separation. As 

 a rule, this method leaves about 20 per cent of the fat in the milk. Milk 

 testing 5 per cent would have 1 per cent of fat left in the skim-milk. If 

 the process is carried out carefully, it is sometimes 2)ossible to skim as 

 low as .5 of 1 per cent. 



Deep Selling. — Some twenty-five or thirty years ago it was discovered 

 that if milk was set in vessels when first drawn, and rapidly cooled at 

 a temperature of 40^ F., and kept at that temperature for twenty-four 

 hours, the depth of the milk could be increased from four to twenty 

 inches, and the separation made much more complete in a shorter time. 

 Several so-called deep-setting systems have been upon the market, the 

 more common one in Massachusetts being the Coolej' process. This 

 method hardly needs an extended description, it having been in very 

 general use among Massachusetts dairymen. The tiii cans employed 

 are some twenty inches deep by nine inches in diameter, covered with 

 tight-fitting covers, and hold eighteen quarts each. The milk is placed 

 in the cans as soon as drawn, and the latter immediately completely im- 

 mersed in water at 40"^ F. and kept there for twenty-four hours. If the 

 milk is from cows that have recently freshened, there will not be much 

 over .2 of 1 per cent of fat in the skim-milk. As cows become advanced 

 in the period of lactation, tlie skim-milk frequently contains from .5 of 

 1 per cent to as high as 1 per cent of fat. Taking the year through, the 

 skim-milk from a herd of cows is liable to contain nearly ,.5 of 1 per cent 

 to 1 per cent of fat. If the milk from a cow producing G,()00 pounds 

 with 4 per cent fat be set by this system, there is liable to be a loss of 

 some 24 pounds or more of butter in the skim-milk. The cream ob- 

 tained by this process is thin, and varies quite widely in the amount of 

 butter fat it contains, the extreme being from 12 to 24 per cent, with 

 a probable average of 17 to 18 per cent. The disadvantages of this 

 method, aside from the loss of fat, consist in the length of time required 

 to secure a separation, and the amount of ice consumed. The chief ad- 

 vantage consists in the fact that no power is required, the milk being 

 poured from the milk j^ail direct into the cans and allowed to remain 

 in the water until the skim-milk is drawn otf. 



Separalion by Dibdion. — This method has been practised to an ex- 

 tent by those who did not desire to employ ice in large quantities. Deep 

 cans similar to Cooley cans were employed, and the milk diluted with 

 one-half or an equal volume of water, and allowed to stand at ordinary 

 temperature for twelve hours. The skim-milk resulting was found to 

 contain from . 70 of 1 per cent to 1 j)er cent of fat. 



Of late, several so-called "dilution or gravity separators" have been 

 placed upon the market, with the claim that a very thorough separation 



