1 86 DYEING 



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red colouring matter is extracted by water, what 

 remains is a resinous substance called shell lac^ used 

 for various purposes, as varnishes, sealing wax, &c. 

 Water dissolves lac, and the decoction is of a deep 

 crimson colour. The precipitate, with alum or 

 nitro-muriate of tin, forms a fine red. 



Brazil-wood is an article used in dyeing. It is 

 the central part of a large tree, that grows in Brazil. 

 It is heavier than water, and affords a decoction of a 

 red colour with water. The precipitate, with alum 

 and nitro-muriate of tin, is a fine red. 



Peach-wood gives a colour inferior to Brazil, and 

 also in smaller quantity. 



Logwood affords a colouring matter extensively 

 used in dyeing. It is very heavy, and sinks in 

 water. Its decoction is yellow, but by alum be- 

 comes violet or purple ; by sulphate of iron it 

 becomes black. 



Carthamus is the flower of a plant cultivated in 

 Spain and the Levant. It contains two colouring 

 matters ; a yellow, which is soluble in water ; and 

 a red, which is insoluble in water, but soluble in 

 alcaline carbon ats. The red colouring matter of 

 carthamus, extracted by carbonate of soda, preci- 

 pitated by lemon-juice, and ground with talc, con- 

 stitutes the rouge employed as a cosmetic: the 

 fineness of the talc, and the proportion of it mixed 

 with the carthamus, occasion the difference between 

 the cheaper and dearer kinds of rouge. 



Wool is died scarlet, which is the most splendid 

 of all reds, by cochineal. Alum will do as a mor- 

 dant for fixing the red ; but nitro-muriate of tin, 

 or what is still better, the murio-sulphate of tin, are 

 now used as preferable mordants. To die wool 

 scarlet, a bath is made by mixing pure tartar with 

 a little cochineal and nitro-muriate of tin 5 but as 



