408 COMPOUND PRODUCTS. CHAP. I. 



except that its shade is somewhat deeper and 

 more permanent. It is much employed in dyeing 

 silks. 



Y^llo \^ Yellow, which is a colour of very frequent oc- 

 currence among vegetables, and the most perma- 

 nent among flowers, is extracted, for the purpose of 

 dyeing, from a variety of plants. 1st, It is extracted 

 from the Reseda luteola of Linnaeus, by the de- 

 coction of its dried stems. The colouring matter is 

 precipitated by means of alum, and is much used 

 in dyeing wool, silk, and cotton. 2dly, It is ob- 

 tained from the Morus tinctoria, a native of the 

 West India Islands, by means also of decoction. 

 The decoction dyes cloth yellow without the in- 

 tervention of any mordant, and throws down a 

 yellow precipitate if mixed with acids. 3dly, It is 

 obtained from the BLva orcllana, a tree that grows 

 in South America, and produces fruit twice in the 

 year. The seeds are bruised and kneaded with 

 a little oil into a paste known by the name of 

 rocou ; from the decoction of which in water, or 

 solution in alkalies, it is precipitated by alum, with 

 which it forms a yellow lake. 4thly, It is obtained 

 by similar processes from the following plants 

 also : Serratula tinctoria, Genesta tinctoria, Rhus 

 Cotinus, Rhamnus infectorius, and Quercitron, the 

 bark of which last affords a rich and permanent 

 yellow, that is at present much in use. 



Brown. The colouring matter of vegetables that gives a 

 brown dye to cloths is very abundant, particularly 



