66 MILK PRODUCTS. 



fats in containing notable proportions of acid radicles 

 with a small number of carbon atoms. The exact ar- 

 rangement is not known, but the weight of opinion is 

 that it is not a mixture of simple fats, but that several 

 acid radicles are united to the same tritenyl molecule. 

 When saponified by sodium hydroxid and treated 

 with acid, the individual fatty acids are obtained. It 

 is upon the recognition of the peculiar acid radicles 

 that the most satisfactory method of distinguishing 

 butter from other fats is based. Since the relative pro- 

 portion of these radicles differs in different samples, the 

 quantitive estimation cannot be made with accuracy, 

 but when the foreign fats are substituted to the extent 

 of 25 per cent, or more, the adulteration can be detect- 

 ed with certainty and the quantitive determination ap- 

 proximately made. 



The fatty acids containing a small number of carbon 

 atoms, set free by the process of saponification and 

 treatment with acid as noted above, are soluble in wa- 

 ter and volatile. A method for their estimation depend- 

 ing on their solubilty in water was perfected by 

 Hehner, but has now been displaced by a distillation 

 method originally suggested by Hehner & Angell, but 

 improved by Reichert and the details perfected by 

 others, especially Wollny, and now generally known 

 as the Reichert-Wollny method. 



We have modified the process by substituting a so- 

 lution of sodium hydroxid in glycerol as the saponify- 

 ing agent, by which the time required is much shorten- 

 ed, the result subject to less variation, and the titration 



