— 144 — 



The best quality of asbestos is washed with dilute hydrochloric 

 acid and distilled water, picked into long fibers and ignited. 



On the perforated disk in the tube a layer of cotton about a 

 centimeter in depth is placed, the asbestos is packed into the 

 tubes, so as to form a column not so dense but that the ether can 

 easily penetrate, and still compactly enough so as to absorb all of 

 the milk in the upper two- thirds of the tube. The tubes are dried 

 and weighed in the way mentioned in the bulletin referred to. 

 From 6 to 8 c.c. of milk are weighed out with a weighing pi- 

 pette, and allowed to drop slowly from the pipette on the as- 

 bestos ; the tubes are dried again and weighed, the loss in weight 

 being due to the amount of water in the sample. These tubes 

 serve the purpose of glass-stoppered weighing tubes, as well as 

 drying tubes. The fat is extracted in the ordinary way, and 

 weighed. 



2. COMPARISON OF THE ASBESTOS AND PAPER METHODS. 



The method as above described has been compared with Adams' 

 paper method, and with the following results : 



Adams' paper method. Babcocks' asbestos method. 



Fats. Solids. Fats. Solids, 



i • . • 3-88 13-37 3-96 13-39 



2. . .4-24 13-24 4-27 13-16 



3 • • • 3-73 I2 -9! 3-77 12.80 



The paper was prepared by treatment with dilute acetic acid, 

 alcohol, and extraction twelve hours, using a return-flow conden- 

 ser, with ether. With each determination of the fat a blank de- 

 termination was carried through, and the amount of extract ob- 

 tained from the paper ranged from .0079 grams to .0091 grams. 

 The average of these amounts w T as subtracted from the several 

 weights of fat obtained. Blank determinations carried on with 

 the tubes filled with asbestos gave no extract. 



Asbestos appears to be superior to paper. Corrections are 

 always necessary on account of the ether-soluble matter in the 

 paper coils ; this is a variable quantity, and when a sample of 

 milk has become acid, the paper will give up a much larger 

 quantity of extract. With skim-milk or butter-milk this fre- 

 quently amounts to a third or a half of the total weight of fat 



