90 



FOODS AND FOOD ADULTERANTS. 



bestos, with a plug of cotton at each end. The milk is absorbed by the 

 asbestos, the tube is then placed in a steam bath and a slow current of 

 air drawn through it by an aspirator. In two hours the desiccation is 

 complete. The method gives satisfactory results. It is inconvenient, 

 however, to work a large number of samples at once by this method. 

 After drying, the tube is placed in a continuous extractor and the fat 

 removed by ether. I have used the following modification of the gravi- 

 metric method. The evaporation is made in a schalchen half filled with 

 fine, pure asbestos. About 5 grams of milk are taken for each deter- 

 mination. The water is driven off at 100 0. and after the total solids 

 have been noted by weighing, the asbestos is removed to the extraction 

 tube. The schiilchen is then finely ground in a mortar, transferred 

 to the extraction tube and the mortar and pestle thoroughly washed 

 with ether. The extraction is then made in the usual way. 



Adams 1 proposes the use of blotting paper rolled into a helical coil as 

 the absorbent of the milk for the purpose of drying and extraction of 

 the fat. Johnstone 2 modifies this method by using disks of blotting 

 paper held in a circular platinum dish. Dr. Vieth 3 hesitates to approve 

 the blotting paper method on account of the fact that blotting paper 

 itself gives up a considerable extract to ether. 



Alien and Chattway 4 recommend certain modifications in Adams' 

 method, consisting in a peculiar method of winding the coil of blotting 

 paper. 



Thompson 5 proposes the use of filtering paper instead of blotting pa- 

 per. I have had this method tried in the laboratory by Mr. Knorr and 

 with pleasing results. Care must be taken, however, to use only filter- 

 ing paper which has been previously thoroughly extracted. It was 

 found that the filtering paper necessary to absorb 5 grams of milk was 

 afforded by a piece 24 inches in length by 2.5 inches in breadth. This 

 paper extracted with ether gave the following residues : 



Since the tables of the Soxhlet method are based on the old method 

 of extraction they will have to be revised for the new data given by the 

 Adams method. 



One great advantage of the Adams method as modified by Thompson 

 I have found to consist in the rapidity with which the preliminary dry- 



1 Analyst, 1885, p. 48. 

 *Wd., 1885, p. 83. 



s lbid., 1885, p. 86. 

 I, 1886, p. 71. 



., 1886, p. 73. 



