THE INDIGENOUS DYES OP BENGAL. 27 



" A Manual of Dyeing," J. Napier, 1875 j " Die Chemie der natiirlichen Farb- 

 stoffe," H. Rupe, 1900; " Commercial Organic Analysis," A. H. Allen, 1901 ; and 

 '' Chemistry of Dye-stuffs," G. von Georgievics, 1903 ; may be taken as representing 

 European opinion during the last thirty years. 



Indigo. — This dye will not be further considered, as it admittedly stands in the 

 very first rank and has been the subject of numerous investigations. 



Safflower. — " The colours obtained by safflower are the prettiest and cleanest 

 that can be had upon cotton, but they are fugitive." — Napier. 



" The shades obtained by dyeing with safflower are very fugitive, discharged com- 

 pletely by quite small quantities of soda, also by chlorine and sulphur dioxide, 

 bleached quickly by light, but not so quickly as the eosin dye-stuffs." — Rupe. 



" The dyeings are very fugitive." — Georgievics. 



Bakam (Ccesalpinia sap-pan). — "All the colours obtained by this wood are exceeding- 

 ly fugitive, losing their brilliancy on a short exposure to air. The sun has a 

 very powerful influence upon colours dyed by this wood By a short exposure 

 the red colour assumes a blackish tint, passes into a brown and fades away into 

 a light dun colour. Heat is also very destructive to this colour." — Napier. 



" The colours obtained are not fast, either to soap, alkalies or acids." — Rupe. 



"These dyeings are not very fast." — Georgievics. 



Latkan or annatto (Bixa orellana). — " All the colours dyed by annatto are exceed- 

 ingly fugitive, and although neither acids nor alkalies can completely remove 

 the colours dyed by it, still they constantly change and fade by exposure to 

 air and light. On this account annatto is now very seldom used in cotton 

 dyeing, and when it is used it is only as an auxiliary. It is, however, still 

 used for silks and woollens, as the objections to its use for cotton do not apply 

 so strongly in relation to these substances " — Napier. 



" The colours dyed by annatto are fine and bright and resist well acids, soap 

 and chlorine. But they easily fade in light." — Rupe. 



Al {Morinda tinctoria). — " On cloth mordanted for Turkey-red, Anderson obtained 

 a dark, brownish-red colour, devoid of beauty but perfectly fixed, with other 



mordants not very stable nor very fast to washing So far as this colouring 



matter is concerned, there is a field of enquiry yet open to the practical dyer." 

 — Napier. 



' Used in a manner similar to Madder in Turkey-red dyeing, one obtains a fast 

 red." — Rupe. 



Manjista (Rubia cordifolia). — " Reds dyed with manjista are very brilliant but 

 fugitive, being destroyed by a short exposure to light and air." — Napier. 



" Dyes cotton, mordanted with alumina or oil, of an orange-red colour, but the 

 colour is not fast to light or soap." — Rupe. 



Catechu. — " Is an extremely valuable dye-stuff. It is used only for silk-dyeing, 

 in cotton-dyeing and calico-printing for browns. The colour obtained is red- 

 brown or grey-brown according as chrome or iron mordants are used ; neither 

 is handsome or bright, but both are extremely fast." — Georgievics. 



