DETECTIOlSr OF LIME USED IN DAIRY PRODUCTS. 



15 



EFFECT OF IMPURITIES IN THE SALT ON THE PERCENTAGE OF 

 CALCIUM OXID IN THE SALT-FREE ASH. 



CALCIUM SULPHATE. 



The most usual impurity in dairy salt and the one present in 

 greatest quantity is calcium sulphate. The amount of salt-free ash 

 in butter will increase with the calcium content if salt containing 

 calcium sulphate is used, but it will not increase in the same ratio. 

 The calcium oxid percentage in calcium sulphate is 41, in the ashes 

 of dairy products it averages about 22 per cent. This difference will 

 cause an increase in the calcium oxid percentage in the salt-free ash, 

 the amount of increase depending upon the quantity of salt used and 

 the amount of impurity in it. 



Street ^ found in 21 samples of salt examined, from 0.30 to 1.23 

 per cent of calcium sulphate and from to 0.35 per cent of calcium 

 chlorid. WolP found in domestic brands of dairy salt percentages 

 of calcium sulphate ranging from 0.31 to 1.87 per cent and of calcium 

 chlorid from 0.02 to 0.65. The maximum allowances for table or 

 dairy salt that have been established by the Department of Agri- 

 culture are: 1.4 per cent for calcium sulphate and 0,5 per cent for 

 calcium chlorid plus magnesium chlorid.^ 



To ascertain the effect of impurities in the salt upon the per- 

 centage of calcium oxid in the salt-free ash, a number of experiments 

 were made. Four unsalted stock butters. A, B, C, and D, were used 

 for this purpose. About 5 pounds of butter were melted and well 

 shaken during solidification. Portions of 200 grams were withdrawn 

 and melted in a bottle with 10 grams of salt of known composi- 

 tion. The butter and salt were well mixed by shaking during 

 solidification. The butter treated in this manner contained approxi- 

 mately 4.75 per cent of salt. This is more salt than the average 

 American creamery butter contains, but it was thought best to work 

 with quantities higher than the average so that a certain amount of 

 margin for variation might be provided. 



The methods employed in the analysis of butter thus treated were 

 the same as those given on page 3. Figures for sulphur trioxid, 

 calculated to calcium sulphate, are also included. In some cases the 

 sulphate was determined by dissolving the ash of 40 grams of but- 

 ter in dilute hydrochloric acid and then precipitating with barium 

 chlorid. In other cases 100 grams of butter were melted and ex- 

 tracted with 50 cc portions of warm water acidulated with hydro- 



^ street, J. P. Thirteenth Report on Food Products. In Conn. Agr. Exp. Sta. Bien- 

 nial Rpt., 1907-08, Pt. IX, p. 595. 



2WoIl, F. W. A Study of Dairy Salt. In Wis. Agr. Exp. Sta. I5ul. 74, pp. 12-13, 

 May, 1899. 



3 U. S. Dept. Agr., Office of the Secretary, Circ. 19, Standards of Purity for Food 

 Products, p. 19. 



