178 THE STOCKFEEDER'S COMPANION 



tion of butter-fat is of some importance, if the feeding 

 of dairy cows is to be properly understood. It consists 

 of glycerine combined with various fatty acids, which 

 may be 



(a) Non-volatile and insoluble in water (palmitic, 



stearic, myristic, and oleic acids). Palmitic 

 acid combined with glycerine gives a fat called 

 palmitin; stearic acid and glycerine, stearin ; etc. 



(b) Volatile and soluble in water (butyric, capric, 

 caproic, and capryllic acids). 



Volatile means that the acids are capable of being 

 distilled off. 



The chief point to bear in mind here is that the 

 characteristic feature of butter, as compared with 

 margarine, etc., is that the former is comparatively rich 

 in volatile fatty acids, while the latter is very poor. 

 These volatile acids are also responsible for the fine 

 full flavour one gets in good samples of butter, whereas 

 ordinary margarine possesses a tallowy, insipid flavour. 



Margarine consists chiefly of non-volatile fatty acids 

 which are insoluble in water. These are also common 

 to butter, but not to the same extent. Generally 

 speaking, the firmer and more solid the fat is at 

 ordinary temperature, the larger is the proportion 

 of palmitin and stearin in it ; while the softer and 

 more liquid it is, the larger is the proportion of 

 olein. 



The following very simple, household method of 

 distinguishing butter from oleo-margarine has been 

 taken from Farmers' Bulletin, No. 131, of the U.S. 

 Department of Agriculture, Washington, D.C. To make 

 this test, a small amount of butter or oleo-margarine, 

 as the case may be, approximately the same size as a 



