28 ILLINOIS STATE DAIRYMEN'S ASSOCIATION 



With these facts being emphasized, and the vakie of soHds 

 not fat being known, the State Food Department intends to see 

 that all milk contains the eight and one-half percent of solids 

 not fat required by law. How are you to tell whether your milk 

 tests up to this standard? This can be done by using what is 

 known as a lactometer test in connection with the Babcock test. 



A lactometer is a float with a graduated stem. The gradu- 

 ations are from 20 to 40. When this float is placed in milk, the 

 bulb will be submerged, allowing only the stem to remain above 

 the surface. If the milk is light, the bulb will sink far into the 

 liquid leaving only a short portion of the stem exposed and the 

 reading on the graduated stem will be low. On the other hand, 

 if the milk is heavy, the bulb will not sink far into it and a long 

 portion of the stem will show above the surface and give a cor- 

 respondingly high reading. 



Temperature also effects the depth to which this bulb will 

 sink into the milk. Cold milk will give a higher reading, than 

 the same milk if warm. For the sake of uniformity and con- 

 venience the temperature of 60 degrees Fahrenheit has been 

 accepted as standard throughout the country. This does not 

 necessarily mean the temperature must be exactly 60 degrees F. 

 when the lactometer test is made, for the reading at any other 

 temperature can be changed to what it would have been had the 

 reading been taken at 60 degrees F. by means of Table i. There- 

 fore, it is necessary when making a lactometer reading to record 

 the temperature of the milk, also. 



Knowing the lactometer reading and the percentage of but- 

 terfat, it is possible to calculate the percentage of solids not fat 

 by the help of Table II. 



Let us say, for example, that we have a milk which when 

 tested by the Babcock test proved to contain 3 :5 per cent oi 

 butterfat, and which gave a lactometer reading of 34 at 52 de- 

 grees F. What would have been the lactometer reading at 60 F. 

 and what is the percentage of solids not fat? 



First we will change the reading of 34 at 52 F. to what if 

 would have been at 60 F. In the column of Table I marked 

 "Temperature of Milk in Degrees Fahrenheit," we find the figure 



