335 
hausted with ether. The ether is finally evaporated from 
the fat solution, and the fat, dried at 100° C., is weighed 
directly. 
ASH. 
A quantity of asbestos, more than sufficient to absorb the 
butter taken when melted, is ignited and weighed ina 
small platinum evaporator. Four or five grams of butter 
are placed in the evaporator, which is put in the drying 
oven till the butter is melted, and, if it contains a large 
quantity of water, till a portion of it is driven off; it need 
not be completely dried. A flame applied to the upper 
portion of the asbestos will ignite the fat, which will burn 
- with a flame, without the application of external heat, till 
the fat is nearly consumed. In this operation the asbestos 
serves as a wick to supply the fat, and it will burn quietly 
with no spurting, unless the butter contains a large amount 
of water. 
After the flame is extinguished, a low heat is applied to 
the bottom of the evaporator and the gases again ignited 
upon the surface. The heat may be gradually increased 
and the ignition should be completed at low redness. The 
ignition is greatly facilitated by a platinum reflector placed 
directly over the evaporator. 
The same portion of asbestos may be used without error 
for several determinations unless the amount of ash should 
be very large. 
CASEIN. 
This has usually been determined by difference, but in 
some cases a determination of nitrogen has been made and 
the casein calculated. For this purpose about 10 grams of 
butter are digested with gasoline or benzine in a 150 cc. 
flask. Ina short time the fats will all be dissolved, leaving 
the other constituents of the butter in the bottom of the 
flask. The fat solution is decanted and a second portion of 
gasoline added, which will remove nearly all of the fat from 
the residue. When the gasoline is evaporated, the nitrogen 
is determined by Kjeldahl’s method. The amount of nitro- 
pen multiplied by 6.33 gives the amount of casein. Results 
ave been satisfactory. 
COLOR. 
The relative amount of color in butters may be deter- 
mined with accuracy as follows: One gram of the fresh 
butter is digested with 15 c. c. of refined kerosene till the fats 
are completely dissolved, and the solutions filtered. The 
filtrate will be colored in proportion to the coloring matter 
of the butter, and may be compared to that from another 
