CHAPTER IV 



THE LACTOMETER AND ITS USE IN DETERMINING 

 MILK ADULTERATION 



42. Quevenne's Lactometer. — The lactometer is a 

 piece of apparatus used for determining the specific 

 gravity of milk. It consists (see Fig. 11) of a bulb 

 weighted with mercury attached to a glass tube of 

 cylindrical form provided with a graduated stem, 

 which enables tlie operator to determine the depth 

 to which the instrument sinks in milk. Numbers 

 registered on the lactometer scale range from 15 to 

 40. These are called the lactometer degrees. If 

 the lactometer sinks to a depth of 31 on the scale, it 

 means that the milk has a specific gravity of 1.031. 

 In normal milk the lactometer shows a specific gravity 

 of 1.029 to 1.034. Between each of the numbered 

 divisions, as 25 to 30, there are five subdivisions, 

 which enable the operator to read to a .001 on the 

 specific gravity scale, or less if care is taken in the 

 observations. 



There are other forms of lactometers in use, but 

 the Quevenne's is generally preferred because of its 

 greater accuracy. A lactometer should always be 

 provided with a thermometer in order that the nec- 

 essary corrections for temperature of the lactometer 

 readings may be made. 



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