72 PHYSICAL DETERMINATIONS. 



Determination of Specific Gravity. The lactometers used 

 in dairy work are of two kinds, the thermo -lactometer and the 

 ordinary lactometer. 



The thermo -lactometer (Fig. 4) consists of a stem on which is 

 marked a double scale, one part reading the specific gravity, and 

 the other the temperature on the enclosed thermometer ; a 

 cylindrical body ; and two bulbs, the upper one being the bulb 

 of the thermometer, and the lower one (containing mercury 



Fig. 6. Vieth's Lactometer. 



or shot) serving for the adjustment. By its means the tem- 

 perature and specific gravity can be read off from the same 

 instrument. 



The ordinary lactometer consists of a stem carrying a scale on 

 which the specific gravity is read ; a cylindrical, or globular, 

 body ; and a bulb containing mercury or shot. 



Soxhlet's lactometer (Fig. 5) contains a scale from 25 (1-025) 

 to 35 (1-035) divided up into suitable divisions (J or y 1 ^). 



