108 plint's itattjral history. [Book XXXIII. 



factured ; much inferior, however, to the native chrysocolla. 

 The method of preparing it consists in introducing water 

 gradually into a vein of metal, throughout the winter and until 

 the month of June ; after which, it is left to dry up during 

 the months of June and July : so that, in fact, it is quite evident 

 that chrysocolla is nothing else but the putrefaction of a metal- 

 lic vein. Native chrysocolla, known as *'uva," differs from 

 the other in its hardiaess more particularly ; and yet, hard as 

 it is, it admits of being coloured with the plant known as 

 *' lutum."^® Like flax and wool, it is of a nature which imbibes 

 liquids. For the purpose of dyeing it, it is first bruised in a 

 mortar, after which, it is passed through a fine sieve. This 

 done, it is ground, and then passed through a still finer sieve ; 

 all that refuses to pass being replaced in the mortar, and sub- 

 jected once more to the mill. The finest part of the powder is 

 from time to time measured out into a crucible, where it is 

 macerated in vinegar, so that all the hard particles may be 

 dissolved ; after which, it is pounded again, and then rinsed 

 in shell-shaped vessels, and left to dry. This done, the chry- 

 socolla is dyed by the agency of schist alum" and the plant 

 above-mentioned ; and thus is it painted itself before it serves 

 to paint. It is of considerable importance, too, that it should 

 be absorbent and readily take the dye : indeed, if it does not 

 speedily take the colour, scytanum and turbistum'® are added to 

 the dye ; such being the name of two drugs which compel it to 

 absorb the colouring matter. 



CHAP. 27. THE USE MADE OF CHEYSOCOLIA IN PAINTIl^G. 



"When chrysocoUa has been thus dyed, painters call it " oro^ 

 bitis,'* and distinguish two kinds of it, the cleansed ^^ orchitis, ^'^ 

 which is kept for making lomentum," and the liquid, the balls 



76 The " Reseda luteola," Dyer's weed, or "Wild woad. See Beckraann'a 

 Hist. Inv. Vol. I. p. 478 — 481, where the identity of the Chrysocolla of 

 the ancients is discussed at considerable length. 



7'' As to the identity of this substance, see B. rxxv. c. 52. 



"^^ These drugs have not been identified. 



'3 " Elutam." Though this is the reading given by the Bamberg MS., 

 " luteam" seems preferable ; a name owing, probably, to its being coloured 

 with the plant " lutura," as mentioned at the end of this Chapter. 



•^o So called, probably, from being made up into little balls resembling 

 the " orobus " or vetch. 



8^ A powder, probably, prepared from " caeruleum." See the end of the 



