248 



stituted by an alkyl or aryl will vield oxy.cen ethers. \Yisbing 

 however to prove this contention definitely, we endeavoured to pré- 

 pare thèse ethers by a method. which would leave no doubt as to 

 the position of the alkyl or aryl introduced, and compare them 

 with the substances obtainable by the old method. To this end we 

 Condensed isatin with a-benzylhydroxvlamine and compared the thus 

 formed isatinoxime benzyl ether with the product of interaction of 

 benzylchloride and isatinoxime silver. This comparison bas shown. 

 that the two substances are identical. and it follows therefrom, that 

 the ethers obtained by Baeycr's method are oxygenethers, and that 

 the constitution of the silver sait may be expressed by one of 

 the followinü: formulae: 



C = NOAi 



or 



N 



C = NOAo 



I 

 C.ÜH 



It remains yet to be shown wliether tliey contain a hydro- 

 xylgroup or not. 



In the last part of the paper results are described which 

 were obtained studying the absorption of ultraviolet rays by isatin 

 and its varions derivatives in alcoholic solutions. Isatin. chloroisa- 

 tin and methyl-isatin cause, in accordance with Hartley's results, 

 a well defined band in tlie région of the kü line and a strong end- 

 absorption. On the other band nitroisatin and acetylisatin show no 

 charaeteristic band, a fact. which may be explained by supposing. 

 that the solutions of these substances contain in realitv nitro or 

 acetylisatic acid. for the sodium sait of isatic acid behaves quite 

 similarly. and nitroisatin and acetylisatin yicld with ease chinoxa- 

 line-derivatives. The oxime of isatin and its benzylether, as well as 

 the oxime of methylisatin cause no charaeteristic absorption bands. 

 From amongst other derivatives we examined indophenazine, chlo- 

 roindophenazine, N-tolyl-ps-indophenazine and N-methyl-ps-indophen- 

 azine. The two first named cause no charaeteristic absorption bands 

 but the two latter give two very distinct bands past the thallium line. 



In deseribing the various derivatives of chinoxaline, indophen- 

 azine. ps-indojihenazine and cumarophenazine we will make use of 

 the following formulae: 



I 



