714 EXPERIMENT STATION RECORD. [Vol.36 



mucic acid is then filtered througli asbestos In a Gooch crucible, washed with 

 nitric acid and water, dried, and weighed. From the weight of the material 

 in the crucible the weight of the added mucic acid is subtracted, and the 

 amount of galactose in the original sample is calculated. 



For determining galactose in glucosids, a moisture-free sample of from 

 0.25 to 1 gm. is hydrolyzed with about 25 cc. of from 2 to 5 per cent sulphuric 

 acid. After the hydrolj^sis is complete the material is allowed to stand for 

 24 hours, filtered, washed with water, dried, and weighed. The filtrate and 

 washings are treated with dilute alkali until only slightly acid, and then 

 concentrated on the water bath. After sufllcient concentration the liquid is 

 made alkaline and 30 cc. of the liquid oxidized with 30 cc. nitric acid (50 

 per cent). The procedure is then carried out as described above for the 

 determination of free galactose. A curve and tables for converting milligrams 

 of mucic acid to milligrams of galactose up to 1,000 mg. galactose are submitted. 



Some analytical data submitted indicate the accuracy of the procedure. 



A thermostat or constant-temperature cabinet for the flour-testing labora- 

 tory, C. H. Bailey (Jour. Indus, and Engin. Cheni., 8 {1916), No. 12, pp. 11^2- 

 1144, fiffs. 5). — The construction of a constant-temperature cabinet, used by the 

 author at the Minnesota Experiment Station in baking and fermentation tests, 

 is described. The thermo-element is so arranged that the cabinet can be used 

 to cover a considerable range in temperature. The apparatus can be constructed 

 at a nominal cost. 



Investigation and determination of hydrocyanic acid in string beans 

 (haricots), L. Guignaed {Ann. Falsi/., 9 {1916), No. 94-95, pp. SOl-305, figs. 

 2). — The preparation of a simple test paper for the detection of hydrocyanic 

 acid in beans is described. The solution used contains 1 gm. picric acid in 100 

 cc. distilled water to which, after complete solution, 10 gm. crystallized potas- 

 sium carbonate is added. The test is performed by hydrolyzing the pulverized 

 sample in a suitable flask and suspending the paper in the neck of the con- 

 tainer. The production of an orange-red color (after sufficient time is allowed 

 for hydrolysis) indicates the presence of a cyanogenetic glucosid. 



For the quantitative determination of hydrocyanic acid in imported beans the 

 silver nitrate titration method with the distilled acid is used. This procedure 

 is deemed to yield sufficiently accurate results. 



The microscopic character of the bean {Phaseolus vulgaris) is also described. 



Separation and identification of food-coloring substances, W. E. Matthew- 

 soN {U. 8. Dept. Agr. Bui. 448 {1911), pp. 55).— This bulletin describes and dis- 

 cusses a scheme of analysis of dyes which embraces about 130 chemical in- 

 dividuals. The method of separation is based mainly on the use of immiscible 

 solvents. 



The general topics considered are reagents used in color analysis, preliminary 

 treatment of food products, separation and purification of coloring substances, 

 and identification of coloring substances. Tabulated data relative to the extrac- 

 tion of coloring substances from aqueous solutions by immiscible solvents, 

 behavior of dry colors or of dyed fibers with reagents, behavior of colors when 

 treated with reducing agents followed by oxidizing agents, classification of 

 colors according to the reactions obtained by the bromin test, behavior of 

 colors when treated with sodium nitrite and with cyanid solution, and the 

 numbers by which dyes are designated in different published tables. 



A modification of Price's method for the separation of the seven permitted 

 coal tar dyes to include tartrazin, C. Estes {Jour. Indus, and Engin. Chem., 

 8 {1916), No. 12, pp. 1123, 1124).— A slight modification of Price's method 

 (E. S. R., 25, p. 502) for determining the permissible coal tar dyes, including 



