Chup. 22] CADMIA. 



tenth part of lead 78 and ono twentieth of silver-lead, this 

 combination being the best adapted for taking the colour 

 known as " Gru3c;Kuens." :u The last kind is that known as 

 " ollaria," 50 from the vessels that are made of it : in this 

 combination three or four pounds of silver-lead 81 are added to 

 every hundred pounds of copper. ]jy the addition of lead to 

 Cyprian copper, the purple tint is produced that we see upon 

 the drapery of statues. 



CII.VP. 21. TIIE METHOD OF PRESERVING COPPER. 



Copper becomes covered with verdigris more quickly when 

 cleaned than when neglected, unless it is well rubbed with 

 oil. It is said that the best method of preserving it is 

 with a coaling of tar. The custom of making use of copper 

 for monuments, which are intended to be perpetuated, is of 

 very ancient date : it is upon tablets of brass that our public 

 enactments are engraved. 



CHAP 22. (10.) CAPMIA. 



The ores of copper furnish a number of resources 82 that arc 

 employed in medicine; indeed, all kinds of ulcers are healed 

 thereby with great rapidity. Of these, however, the most 

 useful is cadmia.^ This substance is formed artificially, 



"* " Piumbi nigri" " black h>a<V literally, but not what ice mean by 

 tlial name. 



"'' Tl>t' '* Grecian" colour. It docs not appear to havo been identified, 

 nor does it appear what it has to do with moulds. 



*" " J'ot" eopjxr, or brass. 



M Ik-ckmnnn is <*' opinion that this *' plumbum nrprrntarium" was ft 

 mixture ot equal parU of tin and lead. Hist. Jnv. Vol. 11. p. 220. Jlo/in's 



J&tittOH, 



' Most of these preparations are in reality highly dan^crou*. Oxides, 

 however, or salu of ropper, liave been employed internally with success, 

 acting by alvine evacuation end by vomiting. The GVor/rv I't.uris of the 

 oKl cncmists \\as an oxide of copper. Jt is still used by the peasants of 

 Silesia, Ajas.-on say*. 



h} It is obvious that the "cadmia" litre described must be an csscn- 

 thilly dillVreiit snh>t:ince from the 4< cadinia " mentioned in the second 

 (Mjiijittr of this Uo.ik, that being a natural production, possibly calamiuc 

 or hydroMiicate or carbonate ot xinc ; while the "cadmiu" of this Chapter 

 i* a furnuce-calamine, a product of the fusion of the ore of copper, or 

 zinc. 1J. It is evident, too, that copper ores, impregnated with zinc oroa- 

 lamirie, also pa.s.vd under this name. Sets Btckmaiin, Hist. Inv. Vol. II. 



p. o.'3 '"), Jlttlinx hlition, where this subject is di>'Mi>M-d at co!i>iderabio 



ngtli ; uUu the tixalibc by l^laiussc, in Lciuuirc's hditiou of 1'liny. 



p 

 tv 



