160 MR. E. R. WATSON ON 



Scarlet RRR (Fr. Bayer & Co.) = Biebrich Scarlet or Ponceau 3R. 

 Fast Pink CGL (Fr. Bayer & Co.) =Magdala Red. 

 Developed — 



Primuline, subsequently treated by Soda. 

 ,, developed with Phenol. 



/?. Naphthol. 

 Adjective — 



Alizarine, dry 50% (Fr. Bayer & Co.). 



That the dyes chosen are well known and commonly used in the silk-dyeing trade 

 may be judged from von Georgievic's observations; he points out that great fastness 

 is not generally looked for in silk dyeing, and that acid dyes are very generally used. 

 In a short list of the more commonly used dyestuffs Orange II is one out of the only 

 two oranges mentioned, and the Ponceaus and Magdala Red are both mentioned in a 

 list of only seven reds. The shade-card above mentioned issued by the Badische Anilin 

 and Soda Fabrik contains only dyeings with 40 different dyestuffs, and of these six have 

 been used in this investigation, viz., Magenta, Auramine II, Orange II, Metanil Yellow, 

 Naphthol Yellow S and Thiazine Red. Again, that several of the dyes chosen have a 

 high reputation for fastness is shown by the following remarks : Hurst, in speaking of 

 dyeing with Primuline developed by /^-Naphthol, says : " The red thus got is bright and 

 fast to acids, soaping and alkalies." Chrysophenine, the same author remarks, "gives 

 bright yellows fast to light and washing " and " all the (neutral) yellow colouring 

 matters are pretty fast to light and resist soaping very well, especially chrysophe- 

 nine." Auramine " gives greenish yellows very fast to light and soaping." Messrs. 

 Cassella & Co.'s select list of dyeings especially fast to boiling off includes Primuline 

 subsequently treated with Soda, Primuline developed with Phenol and the same dye 

 developed with /3-Naphthol. These Primuline dyeings are said to stand a very severe 

 treatment with soap, and their fastness to acids is characterised as very satisfactory. 

 Subsequently treated with Soda, Primuline is designated as eminently fast to light. 

 The same firm includes Orange II in its list of acid colours, all of which are 

 characterised as very fast to rubbing and acids and possessing good resistance to light 

 and ironing. 



The dyed samples were prepared according to the methods described in the 

 publications above mentioned. 



Determination of Fastness of dyed samples. 



As in the case of cotton dyeings, the dyed samples were examined with regard 

 to the following points : — 



(i) Fastness to light, 

 (ii) ,, to washing with soap, 

 (hi) ,, to alkali, 

 (iv) ,, to acid. 



