TESTING BUTTER 645 



Example. 10 grams of butter are tested. 32 c c. of silver 

 nitrate are required to produce a brick-red color. What is the per 

 cent salt? 



32 X .1 = 3.2 per cent salt. 



If, however, the sample of butter, after melting, is made up with 

 water to a 250 cc. solution, and only 25 cc. of this solution are tested, 

 then each cc. of silver nitrate represents 1 per cent salt. Supposing 

 in this case that 3.5 cc. of silver nitrate are required to neutralize 

 the 25 cc. of the 250 cc. solution to which the 10 gram sample oi 

 butter was made up, then the per cent salt would be 3.5 X 1=3.5 

 per cent. In the case of some salt tests the silver nitrate solution 

 is not made as strong as above. Instead of 29.06 grams of silver 

 nitrate per 1,000 cc. water, the solution may be made up to only one- 

 half or one-quarter this strength, containing 14.53 grams or 7.265 

 grams, respectively, of silver nitrate and each cc. would represent 

 only .05 or .025 per cent salt, respectively, if all of a 10 gram sam- 

 ple of butter is used. 



The potassium chromate solution is prepared by dissolving 10 

 grams of dry potassium chromate in 100 cc. of distilled water. 



Salt. Official Method. 1 Weigh in a ' counterpoised beaker 

 5-10 grams of butter, using portions of about 1 gram from different 

 parts of the sample. Add about 20 cc. of hot water and, after the 

 butter is melted, transfer the whole to a separatory funnel. Insert 

 the stopper and shake for a few moments. Let stand until all the 

 fat has collected on the top of the water, then draw off the latter 

 into a flask, being careful to let none of the fat globules pass. Again 

 add hot water, rinsing the beaker, and repeat the extraction 10-15 

 times, using 10-20 cc. of water each time. The washings will con- 

 tain all but a mere trace of the sodium chloride originally present in 

 the butter. Determine the amount in the whole or an aliquot of the 

 liquid by titration with standard silver nitrate, using potassium chro- 

 mate as an indicator. .*.- 



Kohman Salt Test. See Fat Determination by Kohman. 



Determination of Salt by Shaw. 2 

 This is a continuation of the Shaw test for fat in butter. 



1 Journal of the Association of Official Agricultural Chemists, Vol. II, No. 3, 

 November 15, 1916. 



2 Shaw, A New Method for Determining Fat and Salt in Butter, Especially 

 Adapted for Use in Creameries. U. S. Dept. of Agriculture, B. A. I. Circular 

 202, 1912. 



