1^4 ^'^ ^^•''^ Quantify of Sulphur and Iron 



of crabs eyes: they dccrealed 22 parts, and for that reafon, 

 'I prcfunie that this lofs might be afcribed to the water which 

 is found, at lead in the gelatinous matter, fince it is dried as 

 much as poffible ; but as there ftill remains four parts, I 

 afcribe the lofs to a portion of the gelatinous matter which 

 is found dillbh'ed in the liquid employed for the analyfis, and 

 to a fmall quantity of a faline fubflance which I did not exa- 

 mine, and which may be diflblved in it. Should this effay 

 be of any utility, the end I propofed will be anfwered"". 



VI [. Mc-tkod of dctcntwiing the Qnaniify of Sulphur a?id 

 Iron contained in Yelloiu Copper Ore. By B. G. Sage, 

 DireBor ofthefrfl School of Mines f. 



JL HE colour of this ore is a bright yellow inclining to 

 that of gold ; on the furface of it there is often obferved rcd- 

 difh, violet, purple, and greenifli blue varying fliades, on which 

 account it has been called peacock's-tail or pigeon's-neck 

 copper ore. The form of this yellow copper ore is the equi- 

 lateral tetracdron and its varieties. Though it is rare to find 

 thefe cryftals regular, the ore, in a conipa<Sl:, irregular, and 

 fometimes lamollated mafs, is very common; fome of it is 

 met with in the fchiltous imprcffions of fiflxfound at Eifleben 

 and Mansfeld. 



T have faid, in the fecond volume of my Mineralogy, that 

 the yellow copper ore always contains iron and fulphur in 

 greater or Icls quantity : the proportions I have been able 

 10 determine by the following experiments. The yellow 

 copper ore which I employed had no matrix. Having pul- 

 verifcd it in a copper mortar, four hundred grains of it were 

 expofed to torrefaftion in a teft, but, as it was too much 

 healed, the ore became fufed, and produced a yellow compact 

 brilliant mafs, which had a violet appearance in fome parts 

 of its fraflure. This ore was not in the ftate of flag, that 

 is to fay, in a black maf?, as is the cafe when torrefied on x 

 large fcale. 



•'■ Tlis analyfis agrees pretty wtll with tliat of r^Ir. Haichett already 

 given in this Magayitw;, Nos. ;i and ?4. 



f From t'lc jnurna! de Plyx-jl'fic, ri^iria', ^r. c. 



Having 



