THE ANALYSIS OF BUTTER 



73 



and the solution made up to 500 c.c. and filtered; 

 200 c.c. of the filtrate is raised nearly to the boiling- 

 point, and dilute sulphuric acid added till no further 

 precipitate is obtained, the precipitate collected on a 

 filter, washed with water, alcohol, and ether, ignited 

 and weighed ; the difference between the weight and 

 that of the barium sulphate obtained frcm 40 c.c. of 

 the barium chloride solution, multiplied by 1643.5 

 and divided by the 

 weight of fat taken, 

 gives the insoluble 

 baryta value (b). The 

 saponification value is 

 calculated in terms of 

 barium oxide by mul- 

 tiplying the percen- 

 tage of potash re- 

 quired for saponifica- 

 tion (see above) by 

 13.68 (a), and the dif- 

 ference between a and 

 b will give the soluble 

 baryta value (c). 



In genuine butters 

 the value of b (200 + c ) is always negative, and 

 varies from 0.7 to 23.8 ; cocoa-nut oil, margarine, 

 and other fats give positive values. 



The soluble baryta value of butter usually lies between 

 50 and 65, but may be occasionally higher ; cocoa-nut 

 oil gives nearly the same figure, but the soluble baryta 

 value for other fats does not exceed 10. 



Phytosteryl Acetate Method. Fifty grammes of the 

 clear melted fat are shaken with 75 c.c. of warm 95 per 

 cent, alcohol ; the alcohol is cooled and decanted, 

 and a further quantity of 75 c.c. of alcohol is added, 

 and the process repeated. 



The fat is saponified with i c.c. of 50 per cent, caustic 

 soda solution, and the bulk of the alcohol evaporated 

 in a basin ; 2 grammes of sodium bicarbonate and 



FIG. 36. Butter. 



