Some Ancient Dyes. 159 



solution in aniline showed the absorption spectrum of 

 indigo blue. It is evident, therefore, that indigo in some 

 form or other was the material used in dyeing this colour. 



Yellozv. — The colour of the patches dyed yellow was so 

 evidently faded, and showed so little intensity, as to make 

 it very uncertain whether analysis would lead to any precise 

 result; the examination was therefore omitted. 



Green. — Of the material dyed this colour, I had but a 

 small quantity, but it was sufficient to allow of some con- 

 clusion regarding the means whereby the colour was 

 produced. On being treated for some days with dilute 

 hydrochloric acid it imparted to the latter a deep yellow 

 colour. The portion left by the acid, after being washed 

 and dried, yielded indigo blue on treatment with boiling 

 aniline. It is probable, therefore, that the colour was pro- 

 duced by first dyeing the fabric with indigo, then treating 

 with some mordant, such as alum, and, lastly, dyeing with 

 some yellow colouring matter, most likely of vegetable 

 origin. With the small quantity of material at my disposal, 

 I found it impossible to ascertain the nature of the yellow 

 colouring matter employed. 



Red. — This was the most pronounced, and at the same 

 time the most interesting, of the colours examined. The 

 colour of the fabric was a full deep red. It might be called 

 a Turkey red : the dye, in fact, proved on examination to be 

 a kind of Turkey red as having the characteristic properties 

 of that dye. 



On being burnt, the fabric left a considerable quantity 

 of ash, consisting of calcium sulphate, alumina, aluminium 

 phosphate, ferric oxide, and silica. A large portion 

 of this ash no doubt represents the mordant employed 

 in producing the colour. On treatment with hot dilute 

 hydrochloric acid the fabric lost its red colour and became 

 yellow. After removal of the acid by washing with water, 

 and pressing between blotting paper, treatment with boiling 



