1 88 



The Analysis of Dairy Produce [313, 314 



necks are long and graduated, each division representing 

 •04 c.c. 



313. The Operation. — Measure out 18 c.c. of milk into 

 one of the bottles, and add 17*5 c.c. of sulphuric acid (S.G. 1*82). 

 The liquid will become hot and dark in colour. Place the 

 bottle in the machine, and turn it at as high a speed as possible 

 for six or seven minutes. It is best to whirl the bottles directly 

 after adding the acid, otherwise they may cool down and require 



Fig. 47. 



heating again to get the fat in a liquid condition. As soon 

 as the bottles have been sufficiently whirled, fill them up to the 

 base of the neck with hot water. Whirl them again for about 

 two minutes, add more hot water to the top of the 

 graduations, and whirl for a minute more. Stand the bottles 

 upright in water kept at 55 C. for a few minutes, and read off 

 the volume of fat. 



314. Calculation. — Each division of '04 c.c. is equal to 

 •2 per cent, of fat if exactly 18 c.c. of milk be used and the 



