272 REPORT— 1895. 



Notes. — The following Azo colours, reported upon last year, were ex- 

 posed after having been applied as acid-colours : Hessian Yellow, Chrjs- 

 amine E, and G, Cresotin Yellow G, and Carbazol Yellow. Those exposed 

 during the past year, and reported upon now, were applied upon chromium 

 mordant. The results now obtained show that all these colours when 

 dyed on chromium mordant are distinctly faster to light than when dyed 

 as acid-colours. An important additional advantage of the chromium 

 coloui'S is that even after a year's exposure the faded colours appear level, 

 showing none of the speckled appearance so frequently noticed with the 

 faded colours dyed by the acid method. When these colours are applied on 

 aluminium and tin mordants they are more fugitive, and may then be 

 classed as ' fast ' or ' moderately fast.' 



It may be noticed that Madder, Munjeet, and Purpurin give faster 

 colours with tin than with aluminium mordant. 



Silk Patterns. 



All the foregoing colours were also dyed on silk, and the patterns were 

 exposed to light, along with those on wool, with the result that the rela- 

 tive fastness of the various colours was practically the same as on wool. 



The only exceptions were the colours obtained from Morinda-root and 

 from Kamala. Morinda yellow, dyed without the aid of any mordant, 

 is much faster on silk than on wool, and although the colour becomes 

 brownish during exposure, it may be classed as ' fast ' on silk. 



The Indian dyestufi' Kamala was reported upon last year and classed 

 as a ' fugitive ' colour. This year the orange-yellow colour exposed was 

 obtained by applying it in conjunction with alum, and found to be much 

 faster than the colour obtained by dyeing in a simple alkaline bath (Na^CO^). 

 A sample of the rich red-orange colour dyed in India was also exposed. 

 Both dyes examined this year may be classed as ' moderately fast.' 



Isomeric Naphthalene Derivatives. — Ninth Report of the Committee, 

 consisting of Professor W. A. Tilden and Professor H. E. Arm- 

 strong. {Brawn up hy Professor Armstrong.) 



In previous reports reference has frequently been made to the trichloro- 

 naphthalenes : during the past year Dr. Wynne and the writer have at 

 length completed their examination of this series, and have satisfied them- 

 selves of the existence of 14, but only 14, such compounds, which is 

 in accordance with theory. A complete table of the 14 trichloronaphtha- 

 lenes having been published in the ' Chemical Society's Proceedings,' 

 No. 151, 1895, p. 85, it is unnecessary here to further refer to them. 



It may be mentioned that the series is the largest hitherto known 

 isomeric series. 



In completing the work on this subject not only have numerous pre- 

 parations been required, but it has been necessary also to make many 

 chlorine determinations, and the grant has been expended chiefly on these 

 latter. I am specially indebted to Mr. R. L. Jenks for his assistance in 

 the analytical work. 



