12 EXPERIMENT STATION RECORD. * 



Orange I, Orange II, Poncean 3 R, Crocein Orange. Amaranth, Fast Red E, 

 and New Coccin. were given a second crystallization, or salting out, and seemed 

 practically free from organic impurities. 



The methods described are for the determination of Fast Red E and similar 

 colors in Amaranth (E. S. R., 26, p. 506), approximate determination of New 

 Coccin and similar dyes in Amaranth, determination of monosulphonated dyes 

 in Ponceau 3 R, and determination of Orange II in Orange I. " Determined by 

 these methods in the dyes intended for sale as food colors. Amaranth contains 

 from 1 to 5 per cent lower sulphonated colors, and somewhat more New Coccin 

 and similar dyes. Ponceau 3 II contains from 1 to 5 per cent lower sulphonated 

 dyes, and Orange I the same amount of Orange II." 



The identification of small amounts of dyestuffs by oxidation with bromin, 

 W. E. Mathewson {U. S. Dept. Agr., Bur. Ghem. Circ. 114, PP- 3). — "The test 

 to aid in identifjing small amounts of coloring matters, which is described in 

 this paper, has been in use in the New York laboratory [of the Bureau of 

 Chemistry] for some time. It is simple, in many cases very sensitive, and seems 

 to require no special care to obtain reasonabl.v dependable results. 



"A few cubic centimeters of the dye solution are treated with bromin water, 

 added drop by drop until about twice as much has been used as is required to 

 destroy the color. Some hydrazin sulphate solution is then added to talie up the 

 excess of bromin, and finally an excess of sodium carbonate. A second test 

 portion is treated in exactly the same way, except that a few drops of a-naphthol 

 solution (10 per cent in 50 per cent alcohol) are added just before making 

 alkaline with the carbonate." 



The dyes studied in connection with this test were Naphthol Yellow S, Tar- 

 trazin. New Coccin, Amaranth, Fast Red C, New Red L, Light Green S F 

 Yellowish, Erythrosin, Rhodamin B, Alizarin Red S, Safranin, Azocarmin G, 

 Quinolin Yellow, Fustic, Saffron, and Cochineal. 



" In general it may be said that if in testing unknown solutions the dye is 

 bleached by bromin and restored by hydrazin, or if the coloration with 

 a-naphthol and sodium carbonate is different from that with sodium carbonate 

 alone, a coal-tar color is present." 



Sampling cane for chemical analysis, J. T. Crawley (Porto Rico Sugar 

 Growers' Sta. Rpt. 1912. pp. 13. 14). — In securing samples of caue for analysis, 

 tt is practically impossible to obtain those which will be representative 

 of the whole field or plat. In addition to this, when using a small labora- 

 tory mill for grinding the cane, the extraction is not as complete as it would 

 be on a large scale, and, furthermore, there is a notable difference between the 

 composition of the juice expressed and that left in the cane. In order to get 

 accurate data along these lines comparisons were made with the juice obtained 

 by the laboratory mill and from a large sugar mill. 



" There is comparatively little difference in the sucrose and purity of the 

 canes from the different plats according to the factory sample, whereas there 

 is a great difference between the different plats according to the laboratory 

 mill samples. . . . Great differences as to the sucrose and purity would have 

 been indicated where, as a matter of fact, such differences did not exist. 



"As additional data along this line 4 samples were taken from each of 

 2 plats, passed through the hand mill, and the juice analyzed. ... In the 

 first set of samples there was a variation of 6.2 -per cent sucrose and 14.5 

 points in purity, and a variation of 2.3 per cent sucrose and 6 points purity 

 in the second set. In view of these results we must look with suspicion on 

 any general deductions made from results secured by passing small samples of 

 cane through a hand mill." 



