AGRICULTURAL CHEMISTRY — AGROTECHNY. 207 



made up to volume with dilute alcohol, aud filtered. The filtrate is then 

 polarized as usual. 



For inversion 50 cc. of the filtrate is evaporated to remove the alcohol and 

 then inverted in the usual manner. The sucrose is calculated by Clerget's 

 formula. 



A method for the detection of color in tea, E. Alberta Ukxd {Orifj. Gommun. 

 8. Internat. Cong. AppL Chcm. [Washington and New York], 18 {1912), Sect. 

 VIIIc, pp. 301-303). — The method described below was devised for the purpose 

 of detecting color in tea, inasmuch as the chemical methods suggested by Allen, 

 Leach, Villiers, and Collin, and the International Committee for the Unification 

 of Analytical Methods for Food-products can not be used without difficulty 

 where small quantities of color are present, largely because of the masking effect 

 produced by the natural color of the tea. The proposed method has the ad- 

 vantage that it will detect much smaller amounts than are found by the chemical 

 method, although it overlooks traces of color which would be found with a com- 

 pound microscope. It can be used by persons unskilled in scientific methods, and 

 has the additional advantage of being rapid. 



"The articles needed for testing the tea are sieves, 16 to 24 meshes to the 

 centimeter, a spatula or case knife, and a piece of unglazed white paper. A 

 small amount of tea, about 25 to 50 gm., is placed in a sieve and shaken over a 

 piece of white paper. If the tea is tightly rolled, it should be slightly crushed 

 either before putting into the sieve or by rubbing it against the sieve. The 

 dust on the paper is then crushed by dragging over it a spatula or case knife, 

 pressure being applied by the finger to the end of the spatula. This crushes 

 not only the tea dust, but any particles of color which are present. The process 

 of dragging the knife across the paper streaks the color, making it more easily 

 seen. A lens with a magnification of 8 to 12 diameters is useful in detecting 

 the smaller streaks. Sunlight is desirable ; bright light is essential for this work. 

 This method will detect any coloring as blue, tumeric or carbon." It can also 

 be employed for determining whether tea has been faced, but instead of the 

 white paper, black, unglazed paper is used, on which the facing leaves a white 

 streak. 



The chloral hydrate test for charlock, A. L. Winton (Orig. Commun. 8. In- 

 ternat. Cong. AppL Chem. [Washington and New York], 26 {1912), Sects. 

 Vla-XIb, pp. 409-411). — For general use the following reagent and procedure 

 is proposed : 



" Dissolve 16 gm. of crystallized chloral hydrate in 10 cc. of water. To the 

 solution add 1 cc. of concentrated hydrochloric acid. In making the test, mount 

 about 10 mg. of the mustard flour (or an equivalent amount of prepared mus- 

 tard) on a slide in the reagent, heat cautiously (never to boiling) for a moment, 

 and examine under a lens. Note the proportion of fragments of hulls that ac- 

 quire a carmin red color (charlock) to those not changed in color." 



Progress made in the chemistry of milk and dairy products during the 

 year 1911, M. Siegfeld {Chcm. Ztg., 36 {1912), Nos. I40, pp. 1369, 1370; 14I, 

 pp. 1378, 1379; 143, pp. 1394, 1395).— This deals with the advances made in 

 regard to the chemistry, physiology, and technology of milk and other dairy 

 products. The topics are dealt with under the headings of physiology, general 

 chemistry of milk proteins, fats, sugar, ash, enzyms, tests for detecting heated 

 milk, and cream, butter, and milk preparations. 



New method for determining fat in cheese by the acid method without the 

 use of amyl alcohol, W. D. Kooper {Milchw. Zentbl, 41 {1912), No. 24, pp. 

 753-757). — It is a well-known fact that the use of amyl alcohol is undesirable, 

 particularly because it forms compounds with some of the cheese particles 



29663°— No. 3—14 2 



