Lactohutyrometer and Bioscope . 43 



Inventions for testing milk. — Several instruments 

 of European invention have been described for the 

 quick determination of the fat in milk. Some of 

 them make volumetric determinations of the fat or 

 cream ; others depend simply upon the opacity of 

 the milk. One or two are in common use in 

 Germany and Denmark, but, though most of them 

 have been introduced in the United States, none 

 have come into general use. The more important 

 of these are the following : 



MarcJiand^s lactohutyrometer. — This is an instru- 

 ment for quickly determining, volumetrically, the 

 fat in milk. A measured sample of milk is intro- 

 duced into a long glass tube graduated at the 

 upper end. A certain amount of acetic acid is 

 added and thoroughly mixed with the milk, after 

 which ether is added to dissolve the fat, and with 

 the aid of a small amount of heat the fat is col- 

 lected into the upper graduated portion of the tube 

 and read off volumetrically. The lactohutyrometer 

 was introduced about 1877, and was used with 

 more or less success for a time. In certain sam- 

 ples of milk it was found to be difficult to get a 

 clear separation of the fat, and in certain other 

 samples, notablj^ the milk produced from various 

 foods, it was found that the results could not be 

 relied upon. 



Heeren^s piosco2)e. — This is a simple little instru- 

 ment designed to test the quality of milk by 

 means of its opacity. It consists of a hard rubber 

 disc, in the center of which is a small depression, 



