THE ANALYSIS OF MILK 17 



multiplied by 0.009 w iU give the acidity in percentage 

 of lactic acid. 



If greater accuracy is required 50 c.c. may be taken, 

 and 5 c.c. of phenolphthalein solution added ; each 

 \ c.c. will then represent i acidity. 



The Volumetric Estimation of Fat Gerber's 

 method of fat estimation consists in reading the volume 

 of fat brought into the graduated neck of a bottle by 



FIG. 13. Leffmann and Beam Machine. 



centrifuging, after dissolving everything in the milk but 

 fat by strong sulphuric acid (the essential part of Bab- 

 cock's method) with the addition of a little amyl alcohol 

 to help the fat to separate (the essential part of Leffmann 

 and Beam's method (Fig 13) ). In chemical principles 

 Gerber's method is nothing but Leffmann and Beam's, 

 and a description of one only differs in details from that 

 of the other ; as, however, the details of Gerber's method 

 render it more generally suitable, it will be described in 

 preference to its predecessor. 

 Apparatus, The essential apparatus consists of : 



B 



