DAIRY PRODUCTS. &1 



previously weighed, is run into the evaporator and the pipette weighed again. The 

 milk in the evaporator is then dried at 100 C., until the weights taken one-half hour 

 apart do not vary more than a milligram from each other. 



The asbestos serves as an absorbent of the milk and presents a large surface which 

 greatly facilitates the drying. For this purpose asbestos is much to be preferred to 

 sand or any fine powder which requires frequent stirring for complete desiccation 

 When a number of analyses are to be made in succession, a second portion of milk 

 may be dried in the same asbestos with advantage. In the series of analyses made 

 during the feeding experiments the morning's and evening's milk were dried together 

 in this way. The dried residue may be ignited for ash. 



The figures given for solids in, all analyses made during the year have been deter- 

 mined in the above manner. The solids may, however, be found with equal accuracy 

 and in much less time by the method given below. 



In the bottom of a perforated test-tube, such as is used in the estimation of the fat 

 in fodders, is placed a tuft of clean cotton. The tube is then filled three-quarters full 

 of ignited asbestos and a plug of cotton inserted to prevent the escape of loose fibers 

 of asbestos. The asbestos must be slightly pressed together so as to leave no large 

 spaces. The tube and contents are weighed, the plug of cotton carefully removed^ 

 and five grams of milk, from the weighed pipette, described before, run into it and 

 the plug of cotton replaced. The tube, connected at its lower end by a rubber tube 

 and adapter with a filter pump, is placed in a drying oven at 100 G. and a slow cur- 

 rent of dry air drawn through it till the water is completely expelled, which in no 

 case requires more than two hours. 



Since the publication of tbe method of Adams for the estimation of 

 fat, which will be given further on, I have made some attempts to esti- 

 mate tbe water by drying tbe milk on long strips of asbestos paper, 

 wbicb are rolled up wbile still bot and weighed after cooling in a dessic- 

 cator. I bave not yet secured an asbestos paper sufficiently bibulous to 

 make tbis method completely successful. But it has tbe advantage of 

 being very speedy, since on so large a surface exposed for two or tbree 

 minutes to a temperature of 100 to 105 C. over a sand batb the water is 

 completely evaporated. 



An indirect metbod of estimating tbe water from tbe specific gravity 

 bas been prepared by Bebrend and Morgen ! by tbe formula 



S(Y-A) 

 : V 8 l 



in whicb S = specific gravity of tbe milk, S 2 = specific gravity of the 

 milk free of fat, S 1 = specific gravity of tbe milk fat = .94, and V = vol- 

 ume taken = lOOcc. 



Numerous tables are given by tbe authors to sbow the agreement 

 between tbe calculated percentage of fat and total solids obtained by 



e above formula and the gravimetric determinations, 

 nother indirect metbod of determining tbe quantity of water in 



Ik consists in measuring tbe quantity of finely -pulverized common 

 salt a given volume of it will dissolve. 



Tbis procedure was proposed by Keicbelt. 2 



Tbe apparatus consists of a glass vessel 24cm. high. Tbe upper part 

 bas a diameter of 2.5cm. and tbe lower of 8mm. On tbe under side is a 



1 Jour. Landw., 1879, p. 249. 



2 Bayerish Kunst und Gewerbeblatt, 18CO, p. 706. 



19330 Ko. 13 6 



