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Milk. 
M. Emile Mounier, on the other hand, has lately described a 
plan of testmg the quality of milk by determining the amount of 
albumen and casein in it by a standard solution of hyperman- 
ganate of potash. 
As both Paggiale's and Mounier's methods are based on wrong 
principles, the particulars of their processes need not be described 
in this place. 
M. Qucvenne uses two instruments for testing milk ; one 
of which he calls " lacto-densimeter," and the other creamo- 
meter. 
The lacto-densimeter is an instrument similar to a spirit-float. 
The narrow tube of this float bears two scales. One is coloured 
yellow, and indicates the specific gravity of new milk ; and the 
other is coloured blue, and is used for ascertaining the specific 
grav ity of skimmed milk. The degrees on the yellow and blue- 
coloured sides give- in a direct way the specific gravity of new 
and skimmed milk. 
Quevenne's creamometer is sim_ply a graduated measuring 
glass, divided into 100 parts. On both scales the gravity of 
both new and skim-milk, when pure, is marked ; and also the 
specific gravity of milk diluted with 1-lOth, 2-lOths, and more 
of water. 
Chevallier's (jalactomctre centesimale consists of a densimeter, 
thermometer, and creamometer, and its construction is based on 
the same principle as Quevenne's instrument. Like Qucvenne, 
M. Chevallier has two scales on his densimeter, one for new, 
and the other for skim-milk. Except in the mode in which the 
scales are divided, Chevallier's and Quevenne's milk-testers do 
not differ from each other. In pure milk the densimeter sinks to 
a point marked 100 ; and the number of degrees on the scale 
indicate the percentage of pure milk in milk of any quality. 
Thus, if the densimeter sinks in two samples of milk to a point 
marked on the scale 50 or 76, these numbers indicate that the 
samples contain 50 and "76 per cent, of pure milk. 
Any ordinary hydrometer for liquids heavier than water may 
be used for testing milk ; but those hydrometers which indicate 
the specific gravity at once are preferable to others the use of 
which necessitates calculation or reference to tables. 
Hydrometers specially adjusted for testing milk, or lactometers, 
indicating by the point to which they sink in different samples of 
milk, the extent to which they have been mixed with water, are 
sold at a cheap rate by Mr. J. F. Griffin, 119, Bunhill-row, and 
other manufacturers and dealers in chemical and philosophical 
apparatus. These lactometers, or floats, are far more useful than 
1 was inclined to think they were, before I had thoroughly 
