84 MILK PRODUCTS 



is allowed to run into an Erlenmeyer flask, with 

 care not to let fat globules pass. Hot water is 

 again added to the beaker, and the extraction 

 is repeated from ten to fifteen times, using each 

 time from lo to 20 c.c. of water. The resulting 

 washings contain all but a mere trace of the salt 

 originally present in the butter. The chlorin is 

 determined volumetrically in the filtrate by 

 means of standard silver nitrate and potassium 

 chromate indicator and calculated to sodium 

 chlorid. 



Butter-substitutes. — The chief adulteration of 

 butter consists in the substitution of foreign fats, 

 especially the product known as oleomargarin. 



When fats are saponified and the soap treated 

 with acid, the individual fatty acids are obtained. 

 It is upon the recognition of the peculiar acid 

 radicles existing in butter that the most satis- 

 factory method of distinguishing it from other 

 fats is based. Since the relative proportion of 

 these radicles differs in different samples, the 

 quantitative estimation cannot be made with 

 accuracy; but when the foreign fats are substi- 

 tuted to the extent of 20% or more, the adtiltera- 

 tion an be detected with certainty and an 

 approximate quantitative determination made. 



The detection of adulteration of butter-fat by 

 other fats is generally carried out by the deter- 



