IOO MODERN METHODS OF TESTING MILK 



frequently and keep in the boiling water until all the 

 powder is dissolved and the solution is dark brown in 

 color, which usually requires 7 to 10 minutes. After 

 removing the bottle from the water add 12 cc. of strong 

 sulphuric acid (sp. gr. 1.82 to 1.83) and mix thorough- 

 ly, by agitation with a rotary motion taking care to keep 

 the solution from getting into the neck of the bottle. 

 Place the bottle in a centrifuge and whirl 4 or 5 min- 

 utes. Add hot water until the solution reaches the 

 lower end of the neck, whirl again for I minute and 

 then add hot water until the fat rises. Finally whirl 

 again i minute. Read fat column at 130 to 140 F. 

 Readings should be made to 0.05 per cent, on the grad- 

 uated scale. The reading is multiplied by 7.2 to ob- 

 tain the percentage of fat in the material tested. 



