f9 The 'Pron^fs folloxued at Montpellier In 



obfen'fir, Js, that the oxydes of copper obtained by fire are 

 very different from thofp produced by the dpcompofition of 

 acjds on that metal. The colour of them is grey, inftead of 

 being green ; and when the calcination is continued a long 

 time at a violent heat, they niay be concentrated to a red 

 oxyde of ^ blood qolour. This phenomenon was pbferve^ 

 by Kunckel in his chemical laboratory. 



Saline fubftances are not the only ones capable of oxydat- 

 jng copper green. All oils ^nd fat matters produce the fame 

 cffeci. Even water, when left for a cor^fiderable time in 

 copper veffels, caufes an oxydatjon. But what wjll appear 

 very extra,ordinary is, that the greater part of thefe fubftances 

 have no fenfible effe6t upon copper, except when cold, 

 Thofe falts even which corrode that metal when left at reft 

 in veflels, do not ^tt^cjc it in fo fenfible a manner when in a 

 ftate of ebullition. 



Of all the preparations of copper by oxydation, there is 

 none more valuable than tliat made by vinegar, All the 

 vcrdigrife ufed in pommerce is prepared by that acid, and it 

 is at Montpellier in particular and in the neighbourh(jpd, that 

 the manufa&ories of it are eftablifhed. In the Memoirs of 

 the Academy of Paris for 1750 and 1753, may be feen a very 

 exact defcription of the procefs; thpn followed at Montpellier 

 for making vcrdigrife ; but as that procefs ha^ \nten muchj 

 improved, and as at prefent the hufks of grapes are employed 

 inftead of the ftalks, a method far more economical, fmce 

 wjne is no longer ufed, the following account of the rnan- 

 ner of manufa3:uring vcrdigrife, as now praftifed, m^y be of 

 utility to the public, 



The firft materials ufed for this purpofe arp copppr a^id the 

 huflcs or (kins of grapes left after the laft preffing. The 

 copper employed was forinprly all imported from Sweden; 

 but at prefent it is brought from different foundries efta- 

 blifhcd at SaintBel, Lyons, Avignon, Be^arieux, Montpellier, 

 &c. It is in round plates half a line in thicknefs, and from 

 twenty to twenty-five inches in diameter. Each plate at 



Montpellief 



