OCTOBEE 20, 1922] 



SCIENCE 



455 



acid. Tartrates suitable for source of organic 

 acid. Best results in mordanting require careful 

 consideration of combining weights of reduced 

 chrome. Amount of chrome used as mordant 

 should have as near as practical a weight adjusted 

 to combining weight of quantity of dye to be used. 



Influence of tin weighting on the dyeing of 

 silTc: L. J. Matos. 



Quercetin, constitution and uses: Geo. L. Ter- 

 RASSE. A brief synopsis of the constitution of 

 flavone, flavonol and quercetin is given and atten- 

 tion is called to the brilliant synthetic worli on 

 these bodies performed by chemists of repute, 

 these researches leaving no doubt about the cor- 

 rectness of the accepted formulas of the sub- 

 stances just mentioned and other bodies similarly 

 constituted. In spite of the technical importance 

 of quercetin and allied dyes the commercial syn- 

 thetic non-production of them is emphasized. The 

 color of quercetin in relation to its constitution is 

 discussed and the reasons for the adjective dyeing 

 qualities of this dye are considered. The influence 

 of tautomerism, of the alpha hydroxyl and of the 

 hydroxyls in other positions in the molecule are 

 touched upon, as well as the influence of the 

 quinoid formulation on its color. The application 

 of quercetin to the various fibers with several 

 different mordants is recorded and the character- 

 istics of these dyeings are mentioned. The use of 

 this dye on leather is also given and the analogy 

 of the usual commercial forms of the dye to the 

 tannins is indicated. The production of the vari- 

 ous lakes of this color is likewise touched upon. 

 It is pointed out that until the necessary original 

 intermediates be produced much cheaper, or that 

 entirely new and cheap syntheses be developed, 

 quercetin must continue to be produced from nat- 

 ural sources. 



An outline of the history and chemistry of the 

 important natural dyestuffs: David Wallace and 

 Emil Lesser, Ph.D. This paper covers the his- 

 tory of natural colors as used in ancient times 

 and the impetus given to tlie industry by the 

 discovery of America with its source of valuable 

 natural dyestuffs, particularly logwood, fustic, 

 liypernic and quercitron bark. Mention is made 

 of the history of the development of the use of 

 these colors. The chemistry of natural dyestuffs 

 presents an interesting and complex study. It re- 

 ceived j'ears of study by such men as Chevroul, 

 Erdmann, Graebe, Kostanacki, Herzig and Perkin. 

 Most of their work was done on h^motoxylin and 

 brezdlin, the coloring principles of logwood and 

 hypernic. In this country, the work of Perkin 

 has been thoroughly reviewed and extended in the 



search of a method for producing additional dye- 

 stuffs from natural sources. The sources, chem- 

 istry and application of the above mentioned dye- 

 stuffs are discussed. A brief mention is made of 

 the present status of the industry. 



Color and constitution: M. L. Crossley and 

 P. v. EosENVELT. A study was made of the 

 effect of isomerism on the color of certain azo 

 dyes. It is shown that there appears to be a 

 definite relation between the reactivity of the 

 naphthol sulfonic acids of beta-naphthol and the 

 color of the dyes, produced from them. The 

 effect of the suLEouie acid group on the beta- 

 naphthol ring appears to be greatest when it is 

 in position 3. In this position it acts as a bathy- 

 chromic group, while in position 7 it acts as a 

 hypsochromic group. The influence of the nitro 

 group on the benzene ring in an ortho position to 

 the diazo group shifts the absorption of the dyes 

 toward red. This effect is manifested to a maxi- 

 mnm degree by the nitro group in the ortho posi- 

 tion. When the nitro group is in the meta posi- 

 tion it acts as a hypsochromic group, shifting the 

 color of the nitrobenzene-azo-.beta-naphthol-sul- 

 fonic acids in the entire series toward the yellow 

 and beyond that of the corresponding benzene- 

 azo-B-naphthol-sulfonic acid series. The methyl 

 group substituted on the benzene ring has less 

 influence on color than the nitro group. Chlorine 

 appears to have very little influence on the color 

 of the chlorobenzene-azo-B-naphthol-snlf onic 

 acids. Bromine in the ortho position to the diazo 

 group acts as a bathychromic group in dyes re- 

 sulting from P acid and K salt but has no influ- 

 ence on the color of the dyes resulting from G 

 salt and B-naphthol-3.6.8-trisulfonic acid. The 

 sulfonic acid group introduced on the benzene 

 ring shifts the color of the benzene-azo-B-naph- 

 thol-sulfonie acids towards yellow, the maximum 

 effect being manifested by the meta position. 



Constitution and chemical reactivity: M. L. 

 Crossley and P. V. Eosenvelt. It is shown that 

 there is some apparent relation between chemical 

 constitution and reactivity in the B-naphthol- 

 disuKonie acid products. The 2-naphthol-3.6- 

 disulfonic acid, E salt, couples readily with azo 

 compounds to give corresponding dyes, while the 

 2-naphthol-6.8-disulfonic acid and the 2-naphthol- 

 3.6.8-trisulfonic acid, both of which contain a 

 sulfonic acid group in the 8 position, do not react 

 under ordinary conditions for coupling, with cer- 

 tain diazo compounds, particularly those contain- 

 ing a methyl group in an ortho position to the 

 diazo group. Since the hydrogen atom in the ad- 

 jacent position to the hydroxyl group is the only 



