ON MILK AND MILK-TESTING 29 



Describe the graduations on the scale of a board of 

 health lactometer. 

 The scale extends from zero to 120. The zero 

 point is at the top of the stem at the mark to 

 which the lactometer sinks in water at 60° F. 

 When the instrument is floated in cleanly skimmed 

 milk the surface of the liquid would be near the 

 120 mark; 100 marks the point below which the 

 instrument is never expected to settle in pure milk. 

 There are 60 divisions on the scale, each division 

 equaling two lactometer degrees. 



What is the temperature correction for the board 

 of health lactometer? 

 Add .3 to the lactometer reading for each degree 

 of temperature above 60° F., and subtract .3 for 

 each degree below 60° F. If the temperature of 

 the milk is more than 10 degrees from 60 degrees, 

 bring it within those limits before taking the read- 

 ing, as the correction cannot be used for greater 

 variations in temperature. 



Compare the scales on the board of health and 

 Quevenne lactometers. 



The zero point on each is the point to which the 

 instruments sink when placed in water at 60° F. 

 The 29 mark on the Quevenne scale corresponds 

 to the 100 mark on the board of health scale, hence 

 each board of health lactometer degree is .29 of a 

 Quevenne lactometer degree, or the latter is 344+ 

 times greater than the former. 



How may one lactometer reading be converted to 

 that of the other? 



