327, 328] Estimation of Foreign Fats in Butter 197 



Decinormal Baryta Solution. This must be prepared by 

 dissolving about 18 grams Ba(OH) 2 in a litre of water, and 

 standardising with decinormal sulphuric acid as described in 

 paragraph 64. 



327. The Process. — Five grams of the butter fat is weighed 

 in an 8-oz. conical flask; 10 c.c. of the glycerin solution is 

 added, and the mixture is heated on a wire gauze until it ceases 

 frothing, and the solution becomes clear. It is then allowed 

 to cool, and 5 c.c. of freshly boiled distilled water is added. 

 When solution is complete, 50 c.c. of the sulphuric acid is 

 poured in, and the flask at once attached to a condenser. Tt 

 is as well to place a piece of pumice or a piece of clay 

 pipe-stem in the liquid, as it is apt to ' bump ' during the 

 distillation. The flask is now heated until no c.c. of the 

 distillate has been collected. This must be filtered through a 

 dry filter paper into a 100-c.c. flask. 



The 100 c.c. thus collected is titrated with the decinormal 

 baryta. 



328. Calculation. — Add one tenth to the number of c.c 

 of baryta used. If exactly 5 grams of fat has been weighed 

 out, at least 26 c.c. of baryta should be required. Other fats 

 give very small quantities of volatile acid, using about half a c.c. 

 of decinormal baryta. This method is therefore the most 

 useful and definite one when the percentage of foreign fat is 

 to be determined. 



Remarks on the Results of Butter Analysis. — The water in 

 butter should not exceed 12 per cent. The curd and salt 

 together should be less than 8 per cent. The curd should 

 not exceed 4 per cent. 



The keeping power of a butter depends on several circum- 

 stances, such as its general condition, but a butter containing 

 large quantities of nitrogenous matter (curd) will turn rancid 



