230 Testing Milk and Its Products. 



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 

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

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

 later 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 water 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 

 fat in the sample is obtained from the difference be- 

 tween this and the preceding weight. The gooch is 

 then carefully heated over direct flame until a light 

 grayish ash is obtained; this operation is preferably 

 done in a muffle oven to avoid a loss of alkali chlorids. 

 The loss in weight gives the casein in the sample 

 weighed out, and the increase in the weight of the gooch 

 over that of the empty gooch with asbestos, gives the 

 ash (mainly salt) of the butter. The salt in the ash 

 may be dissolved out by hot water, and the chlorin 

 content of the solution determined by means of a stand- 

 ard silver-nitrate solution, using potassium chromate as 

 an indicator. 



