DETERMINATION Otf SPECIFIC GRAVITY 603 



Example. Quevenne reading at 65 F. is 33. What is the 

 corrected reading? 



33 + -5 = 33.5, corrected Quevenne reading. 



For the use of the Quevenne lactometer provide a glass or tin 

 cylinder about 10 inches high and one and one-half inches wide. 

 Fill the cylinder with the milk to be tested. The temperature of the 

 milk should be within the limits of 50 to 70 F. Insert the lacto- 

 meter and when it has found its equilibrium, note the point on the 

 scale at the surface of the milk. This represents the Quevenne 

 degrees. The milk should be free from foam. Freshly drawn 

 milk, and skim milk direct from the centrifugal separator will yield 

 too low readings because of the incorporated air. Such milk should 

 be allowed to stand at rest until the air has had a chance to escape. 



New York Board of Health Lactometer. This type of lacto- 

 meter has an arbitrary scale, it does not show the specific gravity 

 direct. It was originally constructed for the use of milk inspectors 

 in eastern cities, but its use is now only very limited.- 



It has a graduation from zero to 120. The zero point is the 

 point to which this lactometer sinks in water. The 100 mark is the 

 point to which the scale sinks in milk of a specific gravity of 1.029 at 

 60 F., which is assumed to be the lowest^ specific gravity of normal 

 milk, or milk to which no extraneous water has been added. 'The 

 distance between zero and 100 is divided into 100 equal points and 

 the scale is extended beyond the 100 divisions to 120. To convert 

 New York Board of Health lactometer degrees into Quevenne 

 degrees, multiply the B. of H. reading by .29 and to convert Que- 

 venne degrees into B. of H. degrees divide the Quevenne degrees 

 by .29. 



EXAMPLES. 



Milk tests 110 B. of H. lactometer degrees at 60 F. What is 

 the Quevenne reading at 60 F. 



1 10 X. 29 = 31.9 degrees Quevenne. 



Milk tests 34 degrees Quevenne lactometer at 60 F. What is 

 the B. of H. reading at 60 F. ? 



34 



-yg = 117.2 degrees B. of H. lactometer. 



