ON PLATINA AND NATIVE PALLADIUM FROM BRASIL. . JQ 



ed in any other places than Chcco and Santa Fe, whence it 

 was originally brought, until about two years since Mr.Vau- 

 cjuelin discovered it in some gray silver ores from Guadal- 

 canal in Estremadura. In analysinV these ores, he found ^"^' '^'^"'"'^'' 

 . " 1 n 1 aor;om|)anied 



some fragments that contained as mucli as one tenth or their witli the new- 

 weight of platina, but he did not find it accompanied by "'^^^^Is. 

 any of the new metals, that have lately been discovered in 

 the Peruvian ore of platina. 



The specimen which I am now about to describe is de- ^Q™*^ f'o™ 

 rived from a third source, and it is rendered the more inter- ^iUi native 

 estino^ by having grains of native palladium mixed with it. palladium. 

 This new mineral has lately been received from the gold 

 mines in Brasil, by H. E. Chev. de SouzaCoutiuho, ambas- 

 sador from the court of Portugal, resident in this country; 

 and I am in hopes that some account of it may be accepta- 

 ble to the Royal Society, although the analysis must neces- 

 sarily be very imperfect, from the small quantity to which 

 my experiments have unavoidably been confined. 



The general aspect of this specimen is so different from Appearance 

 the common ore of platina, that I could form no conjecture ^'^^''ent from 



,. ,. ••Tif-i • ''^^' "f 'lie 



of what ingredients it might be found to consist. Its ap- common ore of 



pearcnce was such indeed, as at first sight to induce a sus- P'^'^"^* 

 picion of its not being in a natural state, for it had very 

 much the spongy form, which is given to platina from im- 

 perfect attempts to render it malleable by means of arsenic. 



One circumstance, however, occasions a presumption, that Rjt not owing 

 no art has been employed in giving the grains their present ^^ ^^^' 

 appearance ; as upon close inspection many small particles 

 of gold are discernible, but there is none of the magnetic 

 iron sand, with which the Peruvian ore abounds, nor any of 

 the small hyacinths, which I have formerly noticed as ac- 

 companying that mineral*. 



It is very well known, that the common ore of platina in Common ore 

 general consists of flattened grains, that appear so limch ^^ platina d«. 

 worn at their surface, as to be in a considerable degree po- 

 lished, and the roughness observable in some of the larger 

 grains arises from concave indentations of a reddish brown or 

 black colour. The Erai»ilian platina, on the contrary, has Brasilian. 



* Phil. Trans, for 1805, p. Sl8 ; or Jgumal, Vol. XIII, p. ng. 



C2 n» 



