Relation of Quevenne to Ordinary Lactometer. 39 



a specific gravity of 1.029 upon the ordinary hy- 

 drometer. The accompanying sketch (see opposite 

 page) shows the relative 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 are equal to 29 degrees 

 specific gravity, the specific gravity may be obtained 

 by multiplying the ordinary lactometer reading by 

 .29 and adding 1,000. Twenty -nine Quevenne de- 

 grees are also equivalent to 100 ordinary degrees, 

 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 if 

 the temperature is too low, and added if the temper- 

 ature is too high. The amount of such correction 

 for the Quevenne lactometer is .1 of a lactometer 

 degree for each degree of temperature, and for the 

 ordinary lactometer one lactometer degree for each 3 



