CHAPTER VIII. 
I. THE LACTOMETER AND ITS USE. 
This instrument, shown in Fig. 30, is used to determine 
the specific gravity of milk. The stem has two scales 
upon it, a thermometer scale at the upper end and a lac- 
tometer scale at the lower. The latter scale reads from 
fifteen to forty, being divided into twenty-five divisions, | 
each of which reads one lactometer degree. The lower 
end of the instrument consists of two bulbs: an upper one 
containing the mercury for the thermometer scale, and a 
lower and larger one weighted with shot or mercury 
which serves to immerse and to keep in an upright posi- 
tion the:large oblong bulb or float below the stem. 
Making the Test. In making a lactometer test the 
sample of milk is carefully mixed and placed in the 
lactometer cylinder. (Fig. 31.) The lactometer is now 
carefully lowered into it and enough milk is added to the 
cylinder to fill it brim full. Now place your eye in a hori- 
zontal position with the surface of the liquid and read 
down as far as the liquid will permit. The reading thus 
obtained is the correct lactometer reading, provided the 
temperature as indicated by the thermometer scale is 60°. 
Corrections for Temperature. Lactometers are stan- 
dardized at a temperature of 60° F.; but, since it is diffi- 
cult to have a sample always at this temperature, cor- 
rections may be made for temperatures ranging from 50° 
to 70°. As the temperature rises the liquid expands and 
the specific gravity decreases. This decrease amounts to 
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