BUTTER o1 
fat almost as soon as melted, while with process 
butter the fat may remain turbid for a long while. 
When the curd has largely settled, as much of the 
fat is poured off as possible, and the remaining 
mixture is thrown on a wet filter, by which the 
water will drain away, carrying the soluble 
proteins and salt. A few drops of acetic acid 
are added to the filtrate and the mixture is 
boiled. The filtrate from ordinary butter gives 
a slight milkiness, but that from process butter 
gives a flocculent precipitate. Quantitative ex- 
amination is made by dissolving 50 grams of the 
sample in ether; if it is ordinary butter, the curd 
is so finely divided that it remains suspended for 
some time. As much as possible of the solution 
is decanted and the mass transferred to a sepa- 
trator, the casein, water, and salt removed, and the 
remainder washed three times, at least, with 
ether to remove the fat. The curd is collected 
on a filter, washed with water, and the nitrogen 
determined by treating the precipitate with the 
filter by the Kjeldahl-Gunning method. The 
filtrate from the curd is made slightly acid with 
acetic acid, boiled, the precipitated proteins 
collected on a filter, and the total nitrogen de- 
termined. ‘The factor 6.38 may be used in each 
case for converting the nitrogen into proteins. 
A distinction between ordinary and process 
butter may often be made by microscopic ex- 
