Cream of a high fat content and naturally a low percentage of 

 curd, requires slightly less than the regular quantity of acid (17.5 

 c. c.) and this is equally true of samples containing an excess of 

 bichromate of potash (preservative.) Skimmilk, containing slightly 

 more curd than whole milk, and samples preserved with formalin, 

 which hardens the nitrogenous bodies (proteids), need relatively 

 more than the usual amount of acid. 



The machine should be balanced, provided 

 Whirling' and filling, there is not a full battery, by a suitable arrange- 

 ment of the bottles. It should be run for at 

 least five minutes at a speed equal to the theoretical demands for an 

 inner disc of the given diameter. The diameter of the disc is under- 

 stood to be twice the distance between the center of the disc and the 

 point of union between neck of test bottle and bulb when it is 

 whirling. 



Diameter of disc. Revolutions per minute. 



Inches. 



10 1074 



12 980 



14 909 



16 848 



18 800 



20 759 



The test bottle should then be filled to the shoulder with hot water 

 and whirled again for fully two minutes and longer if the fat does 

 not separate clear and oily. After the final filling, which should 

 bring the fat well up into the neck of the test bottle, it should be 

 whirled again for two minutes to perfect the column of fat. 



The percentage can be read more safely and 

 Reading results, accurately by using a pair of dividers to meas- 

 ure the column of fat than by trusting to the 

 unaided eve. 



