10S TLIXT'S NATURAL UISTOIIY. [p,ook XXXIII. 



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

 The method of preparing it consists in introducing \vater 

 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 hardness more particularly ; and yet, hard as 

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

 " lutum."" 6 Like flax and wool, it is of a nature which imbibes 

 liquids. For the purpose of dyeing if, u is tirst bruised in a 

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

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

 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 diy. This done, the chry- 

 Bocolla is dyed by tho agency of schist alum 77 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 78 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 CHUYSOCOLTA IN PAINTING. 



"When chrysocolla has been thus dyed, painters call it " oro- 

 bitis," and distinguish two kinds of it, the cleansed 79 orobitia,* 

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



The ' Reseda luteola," Dyer's weed, or Wild woad. Sec 

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

 the ancients is discussed at considerable length. 



71 As to the identity of this substance, see- B. xxxv. c. 52. 



* d These dru3 have not been identified. 



*' Klutam." Though this is the reading given by the I3ambcr MS., 

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

 with the plant * lutum," as mentioned at the end of'this Chapter. 



* So called, probably, from being made up into little balls resembling 

 tbe 4< orobus " or vetch. 



M A powder, probably, prepared from " ccerulcum." Sec the cud of the 



