Milk. 
315 
same time, a like quantity of the same milk, after having been 
gently shaken in a bottle, threw up only 8 per cent, of cream. 
This shows that the shaking to which milk is subject when sent 
by railway, has the effect of breaking some of the cream 
globules ; in consequence of which either the fatty matters 
remain suspended in the milk, or more probably the cream 
thrown up gets richer in fat. 
Another instrument for ascertaining the quality of milk is 
rionne's lactoscope. It consists of a kind of telescopic tube, 
through which, when filled with milk, you look at a candle placed 
at a distance of 3 feet. The more opaque the milk is, that is, 
the richer it is in cream globules, the shorter will be the telescope 
tube, through which the candle can be clearly seen, and vice 
versa. A graduated index shows the percentage of pure milk in 
water. Donne's lactoscope does not give accurate results, and for 
this reason has never come into practical use. 
Another instrument for determining the amount of butter in 
milk is Marchand's lacto-butyrometer, which is a graduated tube, 
divided into three parts. The first division is marked " milk,"" 
the second "ether," and the third " alcohol." A marked indicator 
slides up and down the tube. This tube works into a wider tin 
tube, or casing, which serves as a water-bath when the milk is 
tested. The milk is poured into the tube up to the second 
division, marked " ether ; " two or three drops of a solution of 
caustic soda are added, and then ordinary ether up to the third 
division, marked "alcohol." The milk and ether are next, 
well shaken together, and afterwards the third division is filled up 
with spirits of wine, containing from 86 to i)0 per cent, of abso- 
lute alcohol. When milk is shaken up with ether, its fatty 
matters are completely dissolved ; and on the addition of alcohol, 
they are again almost entirely precipitated. The quantity of 
fatty matter which remains dissolved in the ether is said to be 
constant. M. Marchand estimates it at 12'6 grammes per litre of 
milk. Finally, the tube is plunged into warm water, of a tempe- 
rature of 104°Fahr., and kept in the heated water until the butter 
is quite melted, forming a layer, which is readily measured by 
the sliding indicator. 
Marchand's lacto-butyrometer requires much dexterity on the 
part of the operator, and therefore is not likely to be used by 
persons who have no experience in chemical manipulation. In 
the hands of a professional chemist this instrument furnishes 
tolerably accurate results. 
M. Poggiale tests the quality of milk by determining the 
amount of ihilk-sugar, either by polarization, or by Fehling's 
volumometrical copper test. 
