n 



Peril a ps too 

 nay contain 

 osmium, and 

 rhodium. 



Palla- 

 diurn dis- 

 tiru'iushable 

 Vv ^bres di- 

 ▼erging from 

 oneextremiiy 



ON PLATINA AND NATIVli PALLADIUM FROM BRASIL. 



larger fra<>;mci)t for the sake of discovering the cause of this 

 appearance. Hot nitric acid dissolved by far the greatest 

 part; but there remained a black powder on which a fresh 

 addition of this acid alone had no farther effect. But when 

 a drop or two of muriatic acid was added, the whole was 

 very soon dissolved. By the addition of muriate of ammo- 

 nia, it became evident from the precipitate, that the residu- 

 um was principally platina. But this precipitate, instead of 

 being yellow, had the deep red colour, which is usually oc- 

 casioned by the presence of iridium. The platina reduced 

 from this precipitate was also too black for pure platina, and 

 when it was again dissolved, the solution was of a deep red, 

 and the precipitate by muviate of ammonia red, as before; 

 so that although the grains of Brasilian plartina appear to be 

 free from iridium, as we'd as from many other impuritie* 

 that form part of the Peruvian ore, yet the grains of native 

 palladium that accompany them affcrd a trace of this in- 

 gredient, and occasion a presumption, that osmium and rho- 

 dium may hereafter appear, when we can obtain this mine- 

 ral in larger quantity. 



Since the whole weight of metal employed in the last ex- 

 periment did not exceed 1 j-V gnsin, it is in vain to attempt 

 to estimate the proportion of the ingredients, but if 1 am 

 near the truth, in considering the quantity of the red pre- 

 cipitate as about one fifth of a grain, of which less than half 

 is platina, those who are best acquainted with the intense 

 colouring power of iridium may endeavour to form a con- 

 ception of the extrer^ely small quantity that can be pre- 

 sent. 



As soon as I had ascertained the existence of native pal- 

 ladium, I endeavoured, by examination of its external cha- 

 racters, to distinguish its appearance from that of the sur- 

 rounding substances, and I found it by no means difficult, 

 although no difference of colour could be discerned. Hav- 

 ing remarked that the larger fragment appeared rather 

 fibrous, and that the fibres were in some degree divergent 

 from one extremity, I examined the remainder of the small 

 specimen which had originally been given to me, and by 

 this peculiarity of structure I soon detected a third frag- 

 ment, which upon trial proved to be the same substance. 



By 



