54 COAL-TAR COLORS USED IN FOOD PRODUCTS. 



albumen and casein, No. 65, Fast Red B, of the Green Tables, has 

 been found to be not harmful by tests actually described; No. 56, 

 Ponceau 3 R, belongs to a class of colors generically permitted by the 

 law of Austria; Nos. 55, Ponceau 2 R, and 106, New Coccine, have 

 been reported on both favorably and unfavorably by different experi- 

 menters; No. 434, Light Green SF bluish on physiological examina- 

 tion has been described as suspicious. 



From this it appears that two colors, physiologically probably 

 harmless, precipitated all the five strengths of albumen, and three 

 colors, which are perhaps no more than suspicious, likewise precipi- 

 tated all five strengths of albumen. 



No. 107, Amaranth, which has been examined with favorable 

 results by two different experimenters, precipitates four out of the 

 five strengths. 



Of the two colors precipitating the first three strengths, both have 

 been examined physiologically with favorable results, namely, Nos. 

 14, Orange G, and 85, Orange I. 



The color which precipitated only the first two strengths, namely, 

 No. 462, Acid Magenta, has likewise been examined physiologically, 

 and the reports are favorable. 



Thus it would seem that there is no definite connection between the 

 physiological action and the ability to precipitate albumen from 

 acetic acid solution in the case of acid colors. 



In the case of basic colors the situation seems to be somewhat 

 different. 



OTHER AUTHORS. 



Rosenstiehl (Fifth International Congress of Applied Chemistry, 

 Vol. Ill, p. 700) states that when the color is present in an excess, 

 yeast absorbs 8 per cent of Magenta (448) and 5 per cent of Malachite 

 Green (427, 428). The Acridins (528-538), the Thionins (649-657), 

 the Safranins (583, 584), and the Rosanilins (447-448) dye yeast the 

 best; solutions containing 3 per cent by weight of the dry weight of 

 the yeast are completely decolorized by such yeast and at ordinary 

 temperatures. The Eosins and Phthaleins dye the yeast only incom- 

 pletely, whereas Azo dyes (7-393) (with the exception of Benzo Pur- 

 purin, 277, 278, 279, 309) do not dye yeast at all. Such dyed yeast, 

 however, is not dead ; it has merely lost its power to cause fermenta- 

 tion. The numbers in parentheses are the corresponding numbers in 

 the Green Tables as nearly as they could be identified. 



Bokorny (CJiem. Ztg., 1906, v. 30, p. 217) examined Magenta (448), 

 Safranin (584), Victoria Blue (487, 488 or 490), Methylene Blue (650), 

 and Alizarin Blue (562 or 563) (the numbers in parentheses are the 

 probable Green Table numbers) as to their effect on micro-organisms 

 such as yeast cells, infusoria, and the like, and found that these dyes 



