I(x6 On Plainia and 



tity to be estimated with correctness, but certainly did not 

 exceed the -y-^of a grain. This, it is to be observed, is 

 another circumstance in which tlie present mineral differs 

 from the Peruvian ore of platina, which I beheve never 

 contains (in the ore itself) the smallest quantity of gold. 



In this experiment also, I tried to detect the existence of 

 palladium in the solution, and by prussiate of mercury aj^ain 

 .ascertained it^ presence; but it was in too small quantity 

 for estimating the proportion it bore to the whole mass. 



It may deserve to be remarked, that though neither the 

 Peruvian nor Brasilian grains of platina contain any silver, 

 yet the gold which accompanies them is in each instance 

 so much alloyed with silver, that from about thirty small 

 scales of gold picked from Peruvian platina, weighing two 

 c^raiiTS, I obtained as much as four tenths of a grain of 

 silver, or one fifth part of their weight. 



Native Palladium, 

 The two fra?"ments, that had been separated from the 

 first solution, next claimed my attention, and evidently de- 

 served a careful examination. They were each placed in 

 a drop of nitric acid, aiul each communicated a deep red 

 colour, which, by the tests of prussiate of mercury and 

 ^reen sulphate of iron, I was satisfied arose from palladium. 

 The smaller fragment was then divided, and one portion 

 •allowed to remain in the acid till it seemed completely dis- 

 solved, and the other examined by the blow-pipe. The 

 utmost Iveatlhat could be given, appeared to have no effect : 

 but when a small piece of sulphur w-as applied to it, it 

 fused instantly; by continuance of the heat, it parted with 

 the sulphur, and became completely malleable In short, 

 it perfectly resembled palladiuni ; aiid as it retained its bril- 

 liancy in cooling, I judged it to be nearly pure. 



But as the surfaces which had beeir acted upon by nitric 

 acid had a degree of blackness, that might be owinc to 

 some insoluble impurity, 1 have since that time dissolved 

 the larger fragment for the sa'.ce of discovering the cause of 

 this a[)pearance. 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 further effect. 

 But when a drop or two of muriatic acid was added, the 

 •whole was very soon dissolved. By i;he addition of muriate 

 of ammonia, it became evident from the precipitate that 

 .the residuum was principally platina. But this precipitate, 

 instead or bemg yellow, had the Jeep red colour, which is 

 usually occa«>ioned by the presence of iridiuna. The pla- 

 tina 



