MILK. 253 



the Best hand-machines on the market at the present time. 

 Steam turbine machines are to be recommended for factory 

 use; they should always be provided with a speed indicator 

 so as to avoid too slow or too rapid whirling; several acci- 

 dents have happened where the bottles were unable to 

 stand the pressure caused by too rapid whirling. In many 

 turbine testers the bottles are heated to about 200° F., and 

 the bottles should in case of such machines be left to cool 

 to about 150° F. before results are read off. Readings 

 taken at temperatures higher than this come too high, viz., 

 in extreme cases, from .2 to .3 per cent too high in case of 

 new milk, and toward one per cent too high in case of 

 cream. (See Wis. Exp. Sta. Report for 18S9-1900.) 



In Sharpies' Russian Babcock Tester (a steam-turbine test 

 manufactured by the Dairy Specialty Co., West Chester, I'a ) the 

 bottles used can be filled with hot water while the machine is 

 in motion ; the test bottles used are arranged for half the 

 usual quantity of milk. 



Points to be watched in making tests by the Labcock 

 method : 



The strength of the acid used is very important; its 

 specific gravity should not go belov/ 1.82 or above 1.84 ; if 

 the acid is somewhat too strong less may be taken, and a 

 Kttle mere if it is rather weak. It is, however, not possible 

 to make a satisfactory test with acid of a specific gravity 

 below 1.82. Keep the acid bottle corked when not in use, 

 as the acid will otherwise take up moisture from the air. 



In testing separator skim-milk use a somewhat larger 

 quantity ol acid than usual, and whirl 5 to 6 minutes; this 

 will insure a nearly perfect separation of all the fat present 

 in such milks. The two-necked so-called Ohlsson bottles 

 are recommended for testing separator skim-milk ; the 

 results should be increased by .05 per cent with these as 

 with other test bottles, in testing separator skim-milk. 



The centrifugal machine should run at a rate of about 

 800 to 1000 revolutions per minute; if its diameter is small, 

 whirl 1000 or 1200. 



Soft or rain-water is used in filling up the bottle after 



