Native Palladmnjrom Brasll, 1 6t 



tina 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 muriate of am- 

 monia red, as before; so that although the grains bf Bra- 

 silian platina appear to be free from iridium, aS well a5 

 from many other impurities that form part of the Peruvian 

 ore, yet the grains of native palladium that accompany 

 them, alTord a trace of this ingredient, and occasion a 

 presumption that osmium and rhodium may hereafter 

 appear, when we can obtain this mineral in larger quan- 

 tity. 



Since the whole weight of metal employed in the last 

 experiment did not exceed lyV grain, it is in vain to at- 

 tempt to estimate the proportion of the ingredients ; but if 

 I am near the truth, in considering the quantity of the red 

 precipitate as about one fifth of a grain, of which less than 

 ialf is platina, those who are best acquainted with the in- 

 tense colouring power of iridium may endeavour to form i 

 conception oi the extremely small quantity that can be 

 present. , . \ ^ ' * - ..;.,,. 



As soon as I had ^ascertaiived lhe,eikistehGe.o)F native ^^^^^^^ 

 Jadium, I endeavoured, by examinatiou of its external cha- 

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

 rounding substances, and I found it by no means difficulty 

 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 

 upecimen 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 favour of the Chev. de Souza I was also ])ermltted5 with 

 this view, io examine the specimen which remained in his 

 possession, and had soon the satisfaction of discovering two 

 more fragments of the same mineral ; and as I was in no 

 one instance deceived in my choice, by attending to the 

 radiating fibres, I am in hopes that this external character 

 will enable persons to distinguish that metal, in situations 

 where they have not an opportunity of deciding by chemical 

 experiment* 



hi XKVIII. On 



