220 



POPULAE, ECONOMIC BOTANY. 



however is giving way to the mineral colours^ in conse- 

 quence of its want of permanency — the fault of most 

 vegetable colours. The consumption is still very con- 

 siderable, amounting to between 500 and 600 tons per 

 annum. 



Shumac or Sumach. — ^The dried and powdered leaves of 

 ^his Cotinus, (Nat. Ovdi.AnacardiacecE.) (Plate XV. fig. 79.) 



This material was known to the ancients, bv whom it 

 ^ was used for tanning as well as dyeing. It contains large 

 quantities of tannin^ as well as a yellow colouring matter 

 similar to that yielded by fustic ; the wood of this plant 

 has been already described as young fustic. It is brought 

 to this country in small bags, of about one hundredweight 

 and a half. More than 13,000 tons were imported in 

 1852. 



Orchella-weed. — -Under this name are imported several 

 species of Roccella, (Nat. Ord. LicJienes.) 



The lichens which constitute the Orchella- weeds of com- 

 merce are of an ash-grey colour, and consist of long thin 

 flat thalli, or leaves, having a mealy appearance ; they are 

 about an inch and a half to two inches in length, and much 

 branched. 



The ancients were acquainted with one or more of the 



