Chemical Analysis of Milk and its Products. 207 



this convenient little apparatus is readily explained 

 verbally. 



For the determination of the specific gravity of loppered 

 milk, see 260. 



250. b. Water. The milk is weighed into a perforated 

 copper tube filled with prepared dry asbestos. The tubes 

 are made from perforated sheet copper, with holes about 

 .7 mm. in diameter and about .7 mm. apart; they are 

 60 mm. long, 20 mm. in diameter and closed at the bot- 

 tom. The asbestos is prepared from clean fibrous asbes- 

 tos, which is ignited at low heat in a muffle oven, treated 

 with a little dilute HC1 (1 : 3) and then with distilled 

 water till all acid is washed out; it is then torn in loose 

 layers and dried at a low temperature in an air bath; 

 when dry it can be easily shredded in fine strings and is 

 placed in a wide-mouth, glass-stoppered bottle. 



About two grams of asbestos are placed in each tube, 

 packing it rather loosely; the tube is then weighed, a 

 small narrow beaker being inverted over it on the scale 

 pan. 5 cc. of milk are now dropped on to the asbestos 

 from a 5 cc. fixed pipette, the beaker again placed over 

 the tube, and the weight of the 5 cc. of milk delivered 

 -f-copper tube taken. The weight of the milk is ob- 

 tained by difference. The tubes are then placed in a 

 steam oven and heated at 100 C. until they no longer 

 decrease in weight, which ordinarily will take about 

 three hours. Place in desiccator until cold, and weigh ; 

 the difference between the weight of the tube+milk and 

 this last weight gives the water contained in the milk, 

 which is then calculated in per cent, of the quantity of 

 milk weighed out. 



