ON ARSENIATED COPPER. Ig^ 



XL 



Ohfervations on Arfeniated Copper, By Hauy *. 



JL HE only ores of arfeniated copper which are well known, Hlftoryof the 

 are ihofe from the county of Cornwall in England. The de- ^'^^^^^'l "/ the 



■' ^ ores, and their 



termination of their true compofition followed clofely on the compofition, 



difcovery of this metallic fubftance, for which we are indebted 



to the fortunate chance wiiich threw forne fpecimens into the 



hands of the celebrated Klaproth. It was in 1787 that hepub- 



lifhed in the Jourti'd de la Soci.te des Curieux de la Nature'^, 



the refult of the examination winch he had made of this new 



mineral. 



The authors who have, fpoken of arfeniated copper fince that 

 period, had only defcribed it under the form of acicular cryf- 

 tals, when Cl'izen Lelievre, member of the Council of Mines, 

 having fufp'::(5led the exiftence of a peculiar fubftance, from 

 the infpedion of a group of green hexagonal bevilled laminae 

 which were given to him, made an elfay of it, and difcovered 

 the prefence of oxide of copper and arfenic acid. Citizen 

 Vauquelin foon afterwards confirmed this indication, and de- 

 termined the proportion of the relative quantities of the two 

 principles contained in ihe fame fubftance. 



About this time the opening of a fecond mine in the county 

 of Cornwall occafioned the re-appearance of arfeniated cop- 

 per, the vein which had been formerly explored being ex- 

 liaufted. ThU difcovery wa.; the more imporlant, as the fub- 

 ftance appeared, in its new fituation, witii characters altoge- 

 ther peculiar, and under forms hitherto unknown. 



M. de Bournon, who was at hand to participate in this in- 

 creafe of riches which refulted to mineralogy, tent to Citizen 

 Gillet Laumont and me, feveral fpecimens chofen from among 

 thofe he polfeffeci ; and that which added to the value of his 

 gift, was his hafte to communicate to u<; the interelting work 

 which he had prepared, on the cryftailography of arfeniated 

 copper, before he publiftied it. 



* Tranflated from a pamphlet in quarto, fent by the author to 

 the Count de Bournon ; probably forming part of a journal, 

 t Tom. VIII. p. 160. 



Mr. 



