33 



by the Gottlieb method of analyzing. An extra loss of o.i to 0.2 

 per cent, means the loss of from I to 2 Ibs. of butter. for every 

 thousand pounds of milk; if the amount skimmed is so small 

 that the difference in the interest on the original cost is enough 

 to equal the loss of fat, then there would be nothing gained in 

 paying a high price for a close skimming machine. But in cream- 

 eries, where the difference between the close-skimming of the 

 separators on the market may make a difference of from 500 to 

 3,000 Ibs. of butterfat, or, say, from $75 up to $600 a year, it is 

 cheaper to buy the very best, even if the old ones must be thrown 

 away. Nor must it be forgotten that there also may be a differ- 

 ence in the individual machines of the same make. 



But there are also other considerations, the durability of 

 the machine, cost of repairs, ease of cleaning and power re- 

 quired. Nor is a test of the skim milk enough. If the construc- 

 tion is such as to retain part of the cream in the bowl in a more 

 or less unavailable shape, this loss should be calculated. Again, 

 if all the skim milk is to be used for cheese or for human con- 

 sumption, the fat left in it will have its full value and it matters 

 less whether the separator leaves 0.05 or 0.25 per cent, of fat in 

 it. If the milk is pasteurized (heated to 160 deg.) and run hot 

 through the machine, the difference between the hollow bowl ma- 

 chines and the others will be reduced to a minimum as far as 

 close skimming is concerned. 



Whenever agents of rival machines are making compara- 

 tive tests, care should be taken to see that the milk has the same 

 temperature, that the speed and the amount of milk run in a cer- 

 tain time are exactly as claimed, that the test run is made as long as 

 the longest run intended. (Fifteen minutes may leave very little 

 fat in the skim milk, while an hour may leave much more), and 

 that no juggling is done with the test. The double-neck Ohlson 

 or the Wagner test bottle should be used, not the common Bab- 

 cock. If you know a disinterested mechanical expert you can 

 rely on, get his- opinion as to durability of the competing machines. 



COMPARING THE VARIOUS CREAMING SYSTEMS. 



There is not a centrifugal separator on the market that is not 

 far ahead of either shallow or deep-setting, even though these, 

 under favorable conditions, for a shbrt time each season, may 

 leave as little fat in the skim milk as do the poorest separators ;. 



