326 BUTTER. 



dissolved in boiling water, and the solution, which should measure 



about 180 c.c, poured into a 250 c.c. flask. The flask is placed 



N 

 on a boiling water bath, and 50 c.c. of ^ barium chloride solution 



are added, with constant shaking. After standing on the water- 

 bath for fifteen minutes, the solution is cooled, and made up 

 to 250 c.c. The solution is filtered, the first portions being 

 poured back on to the filter till the solution runs through clear ; 

 the barium is estimated as sulphate in 200 c.c. of the clear filtrate. 

 The strength of the barium chloride solution is estimated as 

 sulphate in 10 c.c, and 25 c.c. of the alcoholic soda should be 

 neutralised with hydrochloric acid, evaporated, and the residue 

 taken up with water, and a little barium chloride added ; any 

 precipitate of barium sulphate due to impurities should be 

 deducted from the amount of barium sulphate obtained from the 

 50 c.c. of barium chloride added. 



The barium oxide found in 200 c.c. of the filtrate multiplied 

 by 1"25 is deducted from the barium oxide added in 50 c.c. of 

 solution (corrected, if necessary, for the blank), and the value 

 calculated as milligrammes for 1 gramme of fat. This gives 

 the barium oxide combined with the insoluble fatty acids. The 

 potash absorption is calculated as milligrammes of barium oxide 

 per gramme of fat by multiplying by 1'368, giving the total 

 barium oxide, and the difference between the two values gives 

 the barium oxide combined with the soluble fatty acids. To the 

 last value 200 is added, and the value thus obtained is subtracted 

 from the insoluble value. With butters the difference is always 

 negative, varying from — 23 "8 to — 07, and averaging — 9 '6. 



Other fats and oils give positive values ; coco-nut oil giving 

 a difference of 38 '0 to 45 '1, other oils and fats from 46 '9 to 50'3. 

 The soluble l)aryta value usually varies between 50 and 65 for 

 butters, 54'! to 57 'G for coco-nut oil, and is very small for other 

 fats. 



Fritzsche speaks well of this method, and shows that even 

 butters low in Reichert-A\'ollny figures i;ive normal results with 

 the Ave-Lallemant process, and Bolton and Revis also strongh^ 

 recommend it. 



Estimation of Soluble and Insoluble Tatty Acids — 

 Hehner and Angell Method. — The following method has 

 been adopted by the American Association of Official Agricul- 

 tural Chemists ; — 



Reagents required. — Deci-normal sodium hydroxide. 



Alcoholic potash. Dissolve 40 grammes of good caustic 

 potash, free from carbonates, in 1 Vvtre of 95 per cent, redistilled 

 alcohol. The solution must be clear. 



Semi-normal hydrochloric acid accurately .standardised. 



