234 



from air bubbles, and in order to insure this it should 

 stand at least one-half hour after being drawn ; (2) that it 

 should be thoroughly mixed by pouring from one vessel to 

 another, avoiding any violent motions that would be likely to 

 collect air bubbles, then brought to the proper temperature, 

 60° F., placed in a vessel of sufficient depth and diameter to 

 allow the lactometer to float freely, and the mark on the stem 

 to which the instrument sinks read. The lactometer can 

 easily be read to half spaces when it is necessary to be quite 

 accurate. In case it is not convenient to bring the milk to the 

 temperature of 60° F., a correction may be made, where the 

 variation is not more than 10°, by adding to the lactometer 

 reading 0.1 for each degree the temperature exceeds 60°, and 

 subtracting 0.1 for each degree below 60. For example, a 

 lactometer reading of 32 at 65° F., corrected would read 32.5; 

 at 55° F., corrected, 31.5. 



After finding the per cent, of fat, and taking the lactometer 

 reading, the per cent of solids not fat may be found by the 

 table given on page 235. Find the per cent, of fat in one of the 

 side vertical columns, and the lactometer reading at the top 

 of the table in the line of figures marked lactometer reading, 

 then look down the column of figures directly under the lac- 

 tometer reading till on line with the per cent, of fat, and the 

 figures found at this point will be the per cent, of solids not 

 fat in milk. 



For example, suppose the per cent, of fat is 4.5 and the lac- 

 tometer reading is 32, then the per cent, of solids not fat will be 

 8.92. Suppose the lactometer reads 33 instead of 32 in the 

 above example, then the per cent, of solids not fat would be 

 9.17. The per cent, of solids not fat added to the per cent, of 

 fat gives total solids." 



