176 MILK 



"Method 2. — Babcock's Asbestos Method: Provide a hollow 

 cyUnder of perforated sheet metal, 60 mm. long and 20 mm. in 

 diameter, closed 5 mm. from one end by a disk of the same mate- 

 rial. The perforations should be about 0.7 mm. in diameter and 

 about 0.7 mm. apart. Fill loosely with from 1.5 to 2.5 grams of 

 freshly ignited, woolly asbestos, free from fine and brittle material, 

 cool in a desiccator, and weigh. Introduce a weighed quantity of 

 milk (between 3 and 5 grams) and dry at the temperature of boil- 

 ing water to constant weight." 



Plasma solids or solids-not-fat are usually determined by sub- 

 tracting the percentage of fat from the total soHds. 



Attention has been called to the fact that there is a definite 

 relation between specific gravity and the percentage of fat and 

 total solids. Based on this relation Babcock has worked out 

 formulas by which the total solids and plasma soUds can be cal- 

 culated when specific gravity and fat percentage are known. The 

 formula for plasma solids is as follows : 



Per cent, plasma solids = / 10 S. — F. S. i A v^ cinn i? ^ o s 



(solids-not-fat) ^^100 - 1.0753 F. S." ) ^ ^ ■' ^^■ 



S. stands for specific gravity and F. for the percentage of fat. 

 A simplified formula giving approximate results is this : 



Per cent, plasma solids mr t i n o t:^ 

 (solids-not-fat) = "'^^ ^- + ^-^ F- 



For calculating the total solids the following formula is given: 

 Per cent, total solids = 0.25 L. + 1.2 F. 



In these formulas L. is the Quevenne lactometer reading and 

 F. the percentage of fat. 



The table on pages 177 and 178, from Bulletin 134, Bureau of 

 Animal Industry (Shaw and Eckles), gives the total soUds when 

 specific gravity and fat content are known. 



