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A close estimate of the total solids and the solids not fat 

 may be made when the fat content and the specific gravity of 

 the milk are known. Determine the per cent, of fat by the 

 Babcock Test and the specific gravity by the use of the Que- 

 venne lactometer. (Full directions for determining the spe- 

 cific gravity with the lactometer may be found in Farrington 

 and WoU's "Testing Milk and Its Products," pages 80 to 85.) 

 The specific gravity of milk should not be taken until one- 

 half hour (better six or eight hours) after the milk has been 

 drawn, since the specific gravity is always lower if taken 

 immediately after the milk is drawn than it is when the milk 

 has stood for some time. This may be due to the escape of 

 gases or to mechanical changes in the proteids. Be careful to 

 have the temperature of the milk as near 60 degrees F. as 

 possible when the specific gravity is taken. After thoroughly 

 mixing the sample, pour the milk into the lactometer cylinder 

 and take the specific gravity at once before the cream begins 

 to rise. If the cream rises the specific gravity will be that of 

 skim milk. 



Farrington and Woll have derived the following simple 

 formula and rules for estimating the solids not fat and the 

 total solids : 



"Solids not fat equal 1/4L plus .2f 

 Total solids equal 1/4L plus l.'if 

 '^L being the lactometer reading at 60 degrees F. and f the per 

 cent, of fat in the milk. 



" Rule a. To find the per cent, of solids not fat in the 

 milk, add two tenths of the per cent, of fat to one-fourth of 

 the lactometer reading, and 



Rule b. To find the per cent, of total solids in the milk, 

 add one and two-tenths times the per cent, of fat to one-fourth 

 of the lactometer reading." 



The following method of determining the solids not fat is 

 taken from the Maine Experiment Station Report for 1897, 

 page 94; but the table and the method were derived by Prof. 

 Babcock, of Wisconsin Experiment Station : 



^'Method of Haking the Test.— To take the specific grav- 

 ity with the lactometer it is necessary (1) that milk be free 



