THE 



PHILOSOPHICAL MAGAZINE. 



I. Defcr'iptlon of the Arjeniates of Copper and of Iron. By 

 the Count deBovRNoa*. 



T 



SECTION I. 



Arfeniates of Copper. 



HE natural combination of the arfenic acid with copper, 

 and the different afpefts under which this combination ap- 

 pears, according to the proportions in which thefe two fub- 

 ftances are united, were anions: ihofe objefts of mineralogy 

 refpefting which our imperfeft knowledge required the aid 

 of ftudy and obfervation. A new copper mine, lately worked, 

 called Huel Gorland, in the parifh of Gwennap, in the county 

 of Cornwall, having, within the lafi; two years, enriched the 

 cabinets of London with fome very fine fpecimens of thefe 

 arfeniates, I have been induced to pay particular attention to 

 them; and I offer the refult of my obfervations to the Royal 

 Society as an acknowledgment of that gratitude which I and 

 all Frenchmen, faithful to tlieir king, ought to feel and pro- 

 fefs to a country which has diftinguifhed itfelf as the proteftor 

 of honour and loyalty. 



Although there appears, according to fome German au- 

 thors, realon to think that arfeniate of copper has been found 

 in Silefia, its much greater abundance, as well as the various 

 afpefts under which it cxifts, in the county of Cornwall, may 

 entitle it to be confidered as one of the many mineral fub- 

 flances which are peculiar, or nearly fo, to England, 



Of the various works on niineralogv lately publiflied, there 

 are few which have not mentioned arfeniate of copper among 

 tiie ores of this metal. It fecnis, howex'er, that fome of their 

 authors had no knowledge of this ore, except from the very 

 imperfecl account communicated by the celebrated Klaproth, 

 in 1787, in the Schriften dcr Gifc/l/'chaft Naturforjcheiuicr 

 Freunde, vol. vii. in which he has given an interelUng fkctch 



* From Tritnjadiom cf the Royal Society of London for iSox. 



A a of 



