42 PROVISIONAL METHODS FOR ANALYSIS OF FOODS. 



2. METHODS OF DETERMINATION. 

 Determinations in this case should consist of: 



(a) WATER. 



The water can be determined in the usual manner by evaporating a small quantity 

 of the material in a flat dish, so that the film of solid matter may not be too thick. 

 This is preferably done in vacuo or in an atmosphere of inert gas. See Principles 

 and Practice of Agricultural Analysis, vol. 3, pages 13 and following; also Depart- 

 ment of Agriculture, Division of Chemistry, Bulletin No. 46 revised, pages 27 and 43. 



(b) ASH. 



Burn the. dried sample at a low red heat, preferably in a muffle. See Principles 

 and Practice of Agricultural Analysis, vol. 3, pages 36 and following; also Bulletin 

 46 revised, page 23. 



(C) FAT. 



Determine by one of the methods given in Principles and Practice of Agricultural 

 Analysis, vol. 3, pages 480 and following, and Bulletin 46 revised, page 54. 



(d) SUGARS. 



The lactose may be determined both by reduction of copper salts and by optical 

 processes. See Principles and Practice of Agricultural Analysis, vol. 3, pages 275 

 and following; and Bulletin 46 revised, pages 40 and following. 



(e) ADDED SUCROSE. 



Use method of Bigelow and McElroy, Principles and Practice of Agricultural 

 Analysis, vol. 3, page 296; or that of Stokes and Bodmer, Analyst, 1885, 10, 62. 



(f) PROTEIN. 



Use methods described in Principles and Practice of Agricultural Analysis, vol. 3, 

 pages 504 and following, for total protein and separation of protein matters; also Bul- 

 letin 46 revised, pages 54 and 55. 



3. CONDENSED MILK. 



Mix the entire contents of the (tan, transfer 250 grams to a liter flask, dissolve in 

 water and make the solution up to the mark. The solution should then be treated 

 for various constituents as under dairy products on aliquot parts of the contents of 

 the flask. 



4. CARBOHYDRATE FOODS. 



Another class of foods for infants and invalids, as intimated above, is chiefly com- 

 posed of carbohydrate bodies. These foods should be examined microscopically to 

 determine, if possible, the origin and character of the starch. The water and ash 

 should be determined by the usual methods. The quantity of starch unchanged 

 should be determined. See Principles and Practice of Agricultural Analysis, vol. 3, 

 pages 201 and following; and Bulletin 46 revised, page 25. 



(a) DEXTRIN. 



This can be determined in the solution of the bodies after the fermentation of 

 other sugars. Dextrin can then be determined by its opticity or by precipitation 

 with alcohol. See Principles and Practice of Agricultural Analysis, vol. 3, pages 287 

 and following. 



