216 REPORT— 1901. 



The nature of the substitutions in the three benzene nuclei is explained 

 by the author. Observed in thickness of 6 mm. some of the substances 

 show simply a band of transmitted rays in the red, others are also in the 

 violet of much larger extent. The red band is much more persistent, 

 and appareatly is characteristic of the triphenylmethane group of sub- 

 stances and not of the individual members of this group. The band in 

 the red belonging to the greens and blues, Nos. 1 to 1 1 , is narrower than 

 in the remaining colours, which are violet — namely, Nos. 12 to 17. 



Note. — The formulfe given by Nietzki for some of the dye-stuffs 

 examined are the following : — 



1. Malachite green, 

 CoH5C=[C6H4N(CH3).,], 



OH 



2. Urilliant green, 



CeH,C=[CeH,N(C,H,),]2 



I 

 OH 



9. Victoria blue B, 

 (CH3)2N-C,H, /CoHc-NHCcHa 



(CH3),N-CoH/ \ 1 CI 



11. Methyl green. 



/C6H,N(CH3)2CH3C1 

 (CH3),N-C,H,-C/ 



\C6H,N(CH3) 



l\ci 



12. Hexamethylated violet, 



I ^/•'' 



[(0H,),N.C5H.],=C-C.HjN(0H,), 



13, Hexethylated violet, 



A similar formula with C2H5 substituted for CH3. 



The author's summary is as follows : — The colours derived from tri- 

 phenylmethane, which have in general at least two atoms of tertiary 

 nitrogen in the ^jwrci-position relative to the central carbon atom, yield 

 aqueous solutions in which the absorption spectrum transmits a band of 

 rays in the red. The middle of this band is always situated at approxi- 

 mately the wave-length 686 in those compounds which have no more 

 than two tertiary nitrogen groups. The position is invariable, but 

 different for those which include a third tertiary nitrogen group, and lies 

 about wave-length 666. 



