158 MILK AND DAIRY PRODUCTS PART 



foreign fats with butter are nevertheless based upon the 

 presence of these volatile fatty acids. Naturally, either the 

 quantity of non-volatile fatty acids can be determined 

 or the quantity of the volatile water-soluble acids. The 

 former of these determinations is due to Hehner and 

 Angell, 1 and it was the first method used to distinguish butter 

 fat from other fats. The second, the determination of the 

 volatile acids, is the well-known Reichert-Meissl method. 

 Koettstorfer's method for determining the number of acid 

 molecules per unit weight of fat is based upon the same relation. 

 All these methods have been fully described previously. 



Only very bad cases of adulteration can be detected simply 

 by one or the other of these methods, and generally several 

 chemical and physical determinations must be used if 

 an admixture with foreign fats is to be proved beyond doubt. 



(a) Admixture with Margarine. 



Margarine is an artificially prepared substitute for butter, 

 the raw material from which it is made being beef suet. 

 Shortly before the outbreak of the Franco-German war 

 Napoleon III instructed the French chemist, Mege-Mouries, to 

 try to prepare a cheap substitute for butter, principally for 

 army use. The method finally adopted by Mege-Mouries 

 remains unchanged in its chief features even to-day. Fresh 

 suet is melted and separated from skin and connective 

 tissue. The purified melted suet is known commercially as 

 " premier jus," and if allowed to cool slowly after melting it 

 separates into a granular mass with a high melting point, and 

 an oily, low-melting portion. By hydraulic pressure at a 

 temperature at which the oil does not solidify, the oily 

 mass the oleo-margarine can be separated from the high- 

 melting portion. The oleo-margarine is then churned with 

 milk or cream to an emulsion, and afterwards rapidly cooled. 

 By the addition of smaller or larger quantities of vegetable oil 

 (generally earth-nut or cotton-seed), the consistency of the 

 oleo-margarine can be regulated so that it becomes quite the 

 same as that of butter. 



Margarine, in its appearance, microscopic structure, and taste, 

 resembles natural butter to such a high degree that it is almost 



1 Hehner and Angell, Butter, its Analysis and Adulterations, London, 1877. 



