244 Some Experiments on skimmed Milk, 
is of much greater specific gravity than water, and its density is 
diminished in direct proportion to the quantity of water added to 
it. On those facts, the lactometer I have made depends; it is 
exclusively adapted to skimmed milk, in which respect, as well as 
in simplicity of construction, it differs from the ingenious instru- 
ment of Mr. Dicas. 
Description of the Lactometer, ec. 
This instrument (as will appear from the accompanying plate) 
differs but little in form from the common hydrometer. Its di 
stinction is to be found in its seale, which is adapted to skimmed 
milk. It is made of brass, and consists of a pear-shaped bulb, 
at the top of which is a graduated stem, and at the bottom a 
brass wire to the end of which a weight is screwed. The scale 
begins about three-fourths of an inch from the bottom of the 
stem, and is marked 0, which corresponds with the specific gra- 
vity of the lightest genuine skimmed milk, or 1:035, distilled 
water being 1-000. The dots and figures which extend from 0 
to 85, indicate ‘* parts of water in 100 parts skimmed milk at 
60°,” as is engraved on the reverse of the stem, and has been 
ascertained by experiment. The instrument is constructed for 
the temperature of 60° of Fahr., a point judged the most conve- 
nient, as it agrees very nearly with the temperature of the milk 
brought to our markets during the summer. As all fluids ex- 
pand by heat and contract by cold, in using the lactometer an 
allowance must be made of 1° on the instrument for every 
3° of temperature, that the milk under examination is either 
above or below 66° of Fahr. Thus the lactometer, which would 
remain at 0 in milk of the temperature of 60°, would sink 1° 
below 0, if the temperature of the milk were increased to 63°, 
2° if it were raised to 66°, &c. And on the contrary, if the tems 
perature of the same milk were reduced to 57°, the instrument 
would then experience a rise above 0 equal to 1°, &c. This 
lactometer is made by Mr. Bennett, niathematical instrument 
maker, Cork, and sold in a tin case, either with or without a 
sinall thermometer. It is scarcely necessary to give directions 
for using so simple an instrument. All that is required is, to fill 
the tin case with the milk to be examined, immerse the lacto- 
meter in the milk, and observe the point at which it remains 
stationary after it rises. Note also the temperature of the milk, 
and, if necessary, make the allowance directed for expansion or 
contraction of volume. 
Before this lactometer was used in the milk markets, experi- 
" ments were made with it in the presence of the Mayor of Cork, 
Sir A. Perriere, Knt., the Committee of whom I have spoken, 
and other gentlemen, who expressed themselves satished with 
the 
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