11 



figures, directly the speaific gravity. All other instruments, witli 

 scales differing from this, have been abolished on the European 

 continent. It is only in England, and through English influence 

 iti America, that instruinents with arbitrary scales are as yet in 

 use. The principle upon which these are constructed is a wrong 

 one, and they possess, moreover, useless appendages. It is never 

 required to use the lactodensimeter for degrees below a specific 

 gravity of 1.015, and all those degrees below this are, therefore, 

 useless. The scale appears long, but its actually useful part is ex- 

 ceedingly short. 



Quevenne's areometer has, for the specific gravities of from 

 1.015 to 1.040, on a scale of 5.5 cm. length, 25 degrees, and 

 allows thus easily the reading of half degrees ; while a so-called 

 lactometer has, on a scale of 7.8 cm., 120 degrees, with a space of 

 0.065 cm. for each degree. For milk, this subdivision lays below 

 the actual possibility of accurate reading. 



The reason that such areometers, with arbitrary scales, have 

 remained in use for so long a time, is explained by the fact, that men 

 without intimate knowledge of the subject, and without desire to 

 obtain it, find it easier to go on with their investigation by making 

 a so-called authority responsible for their results, without consider- 

 ing that many of these so-called authorities frequently adhere to 

 and defend their wrong positions, even after they have been 

 proved to be untenable. 



Another drawback for the practical application of those lacto- 

 meters is to be found in the fact that no tables exist for tlie correc- 

 tion of the error created by the reading of the instrument at a 

 temperature M-hich is not the normal temperature. Every sample 

 tnuHt be cooled or warmed to 60° F. The usefulness of the in- 

 strument is thereby considerably lessened. 



Description of Quevennis Lactodensimeter. 



The lactodensimeter of Quevenne is an ordinary areometer. 

 It is made of glass, and is 22 cm. long. It consists of a hollow 

 body, kept in an upright position by a weighted globe at its under 

 end ; above, it carries the 6 cm. long stem which bears the scale. 



