206 THE dairyman's manual. 



lactometer for testing the quality of milk. The use of 

 the lactometer, or rather the hydrometer or water meas- 

 ure, for testing millv is a dekision and a snare. This in- 

 strument is constructed for measuring the relative spe- 

 ' cific gravity of liquids, pure or distilled water, water at a 

 temperature of sixty degrees being taken as the standard. 

 The so-called lactometer or milk measure is in its very 

 name a fraud and a delusion, because it does not in 

 reality measure milk, but merely the water in it and the 

 specific gravity of the fluid which shows the quantity of 

 solids in solution or suspension in it. Milk is a complex 

 fluid containing a certain proportion of water, mixed 

 with an uncertain proportion of various salts, some case- 

 ine and some sugar which are heavier than water, and 

 some fat and volatile oils which are lighter than water. 

 Now, it is an utter impossibility for any measurer of 

 specific gravity to ascertain what the true relative gravity 

 or weight of a liquid should be when it contains every 

 time a different quantity or proportion of each one of 

 these added substances and each one differing somewhat 

 in its own specific gravity. For instance, we take the 

 milk of a poor cow, that will not show more than three 

 or four per cent of cream, and ^' measure" it — as the term 

 ''lactometer" really means — and find that this instrument 

 marks 1.030, which is considered to indicate an excellent 

 quality of milk, and this because the milk contains the 

 normal amount of other solids besides fat, and these are 

 all heavier or of a greater specific gravity than the fat. 

 Hence this poor milk would pass muster with the inspec- 

 tor. But if we take the milk of a Jersey or Guernsey cow 

 with fifteen or twenty per cent of cream in it, and sub- 

 ject it to the lactometer, it may mark only 1.038, and it 

 is an understood rule with milk inspectors that milk of 

 so low a specific gravity as 1.028 is suspicious and sub- 

 jects the seller to the pains and penalties of arrest, and, 

 on conviction, fine and disgrace. A painful case occurred 



