Relation of ‘Quevenne to Ordinary Lactometer 81 
a specific gravity of 1.029 upon the ordinary hy- 
drometer. The accompanying sketch (see opposite 
page) shows the rélative values of the degrees upon 
the ordinary hydrometer, the ordinary lactometer and 
the Quevenne lactometer. With the Quevenne lac- 
tometer the specific gravity of the milk can be at 
once read, a degree upon this scale being equivalent 
to one degree of specific gravity. Since 100 degrees 
upon the ordinary lactometer indicate a specific gravity 
of 1.029, the specific gravity of any ordinary lactometer 
reading may be obtained by multiplying the reading by 
.29, dividing by 1,000 and adding 1. Twenty-nine Que- 
venne degrees are also equivalent to 100 ordinary de- 
grees, so that Quevenne readings may be changed to the 
ordinary readings by dividing by .29, and ordinary 
readings may be changed to Quevenne readings by 
multiplying by .29. 
The relative density of milk varies with its tem- 
perature, so that a hydrometer is only correct at one 
given temperature. Most hydrometers are graduated 
for a temperature of 60° F., and the better forms 
have an attached thermometer; so that if the milk 
to be tested varies from this in either direction a cor- 
rection must be made. As the density increases with 
a reduction of temperature and decreases with a rise 
of temperature, the correction must be subtracted in 
going from a lower to a higher and added in going from 
a higher to a lower temperature. The amount of such 
correction for the Quevenne lactometer is .1 of a lac- 
tometer degree for each degree of temperature, and for 
the ordinary lactometer one lactometer degree for each 3 
