232 Testing Milk and Its Products. 



the chemicals used is determined by blank trials and 

 deducted. The nitrogen multiplied by 6.25 gives the 

 casein in the butter. 



269. d. Ash. (1) 10 grams of butter are weighed 

 into a porcelain dish and treated twice with gasoline, as 

 in the preceding determination; the solution is filtered 

 through an ash-free (quantitative) filter, and the filter 

 when dry is transferred to the dish. The dish is heated 

 in an air-bath for half an hour and then placed in a 

 muffle oven, where the contents are burnt to a light 

 grayish ash ; the dish is now cooled in a desiccator and 

 weighed. The difference between this weight and that 

 of the empty dish gives the amount of ash in the butter 

 weighed out. 



270. (2) About two grams of butter are weighed into 

 a small porcelain dish, half filled with stringy asbestos ; 

 the dish is dried for half an hour in the water oven, 

 and the fat then ignited with a match, the asbestos 

 fibre serving as a wick. When the flame has gone out, 

 the dish is placed in a muffle oven, and the residue 

 carefully burnt to a grayish ash. After cooling, the dish 

 is weighed, and the per cent, of ash in the butter calcu- 

 lated as under method 1. 



271. Complete analysis of butter in the same sam- 

 ple. About 2 grams of the butter are weighed into a- 

 platinum gooch half filled with stringy asbestos, and 

 dried in a steam oven at 100 C. to constant weight, 

 cooled and weighed. The difference gives water in the 

 sample. The gooch is then treated repeatedly with 

 small portions of gasoline, suction being applied, and 

 again dried in the water oven, cooled, and weighed ; the 



