48 MILK AND DAIRY PRODUCTS PART 



ether, the fat can be dried and weighed. They are the oldest of 

 all methods for the estimation of fat in milk, and numerous 

 modifications of the actual operation have been proposed and 

 used. 



Originally, ignited sand, powdered pumice stone, gypsum, 

 asbestos, or powdered glass were used, but now either paper 

 (Adams) or granular kaolin (Nilson) are most usual, and only 

 these will be described here. 



(a) Adams s Paper Coil Method. 



Adams's x method consists of drying a weighed quantity of 

 milk upon a strip of fat-free unsized paper, which, when dry, 

 is rolled into a coil, and extracted with ether or petroleum 

 ether in a suitable apparatus. The firm of Schleicher and 

 Schiill, Diiren, prepare special strips of paper for this purpose, 

 they measure 55 or 56 cm. in length and 6 cm. in width. The 

 method as now practised is as follows: To weigh out the milk 

 a small glass wash-bottle, weighing about 30 g., is used ; it 

 is about 8 - 5 cm. high, diameter some 3*0 cm., and a mark is 

 made for each 5 c.c. contents. The jet is dra\\n out to a very 

 fine point. The milk which is to be examined is then thoroughly 

 mixed, poured into the clean dry bottle, and the whole weighed. 

 After this, a clean piece of rubber tubing is attached to the 

 mouth-piece of the bottle, and about 10 c.c. of well-mixed milk 

 are blown on to the strip of paper, 2 which has been suspended 

 horizontally. 



After the milk has been brought on to the paper, the bottle 

 is again weighed, and the difference shows the amount of milk 

 used. The strip of paper is allowed to dry in the air, then 

 rolled together, fastened by means of a fine platinum wire, and 

 dried in the water-oven for two hours at 100 C. It is best to 

 suspend the coil from a loop of platinum to keep it out of 

 contact with the walls or floor of the drying-oven. 



After the drying is complete, the coil is put into a suitable 



1 The Analyst, 1885, p. 46. 



2 Where extreme accuracy is needed, the specially prepared strips of 

 paper should be extracted for several hours with ether before being used, for 

 they are seldom absolutely free from materials soluble in ether (resins). At 

 least, in such an extraction there is always a residue of a few milligrams, 

 part of which, however, is fine paper fibre. With ordinary filter paper a 

 previous extraction with ether is a necessity. 



