CHEMISTRY. 197 



opinion extraction witb the latter is not complete. The following con- 

 clnsions are reached : 



(1) LoNv boiling petroleum ether is the only sort suitable for the 

 determination of fat in flours and in vegetable products in general. 

 The fat content of flour gives an idea of its fineness, since the fat bears 

 a definite relation to the increase in bran; that is, to the coarseness of 

 the flour. 



(2) The fat in the starchy part of the kernel has a different composi- 

 tion from that of the hull. The latter is richer in unsaturated fatty 

 acids. It is possible that the fat in the starchy part of the grain has 

 undergone polymerization or oxidation on being stored as a reserve 

 material. 



(3) The fats of wheat and rye flour are somewhat different, and the 

 difference can serve as a means of identification if the sample is a very 

 fine flour. A determination of the iodin number of fat furnishes no 

 clue to a mixture of wheat and rye flour if both are coarse. The index 

 of refraction of wheat and rye behave differently. That of wheat flour 

 fat stands in inverse proportion to the iodin number. That of rye flour 

 fat increases with the coarseness of the flour. 



{4 ) When flour is very dry the iodin number of the fat is influenced 

 by the polymerization of the unsaturated fatty acids and becomes 

 lower, just as is the case when fat from flour or other cereals is heated 

 for some time. It is best to extract fat in the cold with petroleum ether 

 and remove the latter and dry the fat on a water bath in an atmosphere 

 of hydrogen. 



(5) The fat from old flour, which has become moist, has a lower iodin 

 number tliat the fat from normal flour. 



Analysis and composition of canned meats, E. Hefelmann 

 {Pharm. Centhl., 30 {1895), p. 652; ahs. in Yierteljahr. Chcm. Kahr. und 

 GcnussmtL, 10 [1895), Xo. 4, pp. 485, 486). — Methods for sampling and 

 analyzing canned meats are given and a number of analyses made 

 by Xaumann, of I'lauen. Dresden, are quoted. The chief difference 

 between these methods and those ordinarily followed is in the determi- 

 nation of fat, which was made as follows: Weigh 6 to 7 gm. of the 

 sample in a glass tube () cm. long and 1 cm. wide, inside measurement, 

 open at each end; place in a graduated tube; add '2ii cc. fuming hydro- 

 chloric acid (specific gravity 1.19); place the graduated tube in a cold 

 water bath ; heat ([uickly to boiling, and shake the tube often. In half 

 an h(mr the protein will be dissolved. Dilute the contents of the tube 

 with 20 cc. cold water, cool to 30°, add 30 cc. ether, and shake gently. 

 Cool, fill the tube with ether, cork it, and shake. Allow the contents 

 to settle 2 hours, note the volume of ether, draw off" 20 cc. with a 

 pipette, evaporate the ether in a small beaker glass, dry 1 hour at 100 

 to 110^, and weigh the fat. From this compute the fat content of the 

 whole sample. 



Copper cyanid reagent for the determination of glucose, A. W. 



