NEW METAL FOUND IN CRUDE PLATINA. 41 



very obfervable; namely, lhat in viewing any cryftal obliquely^ 



it appears of a dull brown, that ariies from a mixture of the 



red and green.* 



The characters of palladium that have been enumerated, un- Probability that 



doubtedly belong to none of the fimple fubftances that we are w^s miilllto* 



acquainted with; and no experiment that I have wade, has infer that palta- 



tended to confirm the fufpicion of its being a compound, con- lum ls a corri - 

 ' n . r ... rrn • pound, from its 



fining or any known ingredients. The experiments above being found in 



related, fhow evidently, that the ore of platina contains a very P latin a- 

 fmall quantity of palladium ; and it is not unlikely that this may 

 have been a constituent pari of fome of the compounds obtained 

 by Mr. Chenevix, and may have milled him, by fome pro- 

 perties which he would consequently obferve, into the fuppo- 

 fition that he had formed palladium. 



It is not, however, without having repeatedly endeavoured to All attempts of 



imitate his experiments, that I have ventured to diffent from the autho . r t0 



. r . compare it were 



luch authority. I made many attempts to unite pure platina unfuccefsful. 



with mercury, by folution, and by amalgamation; but without 



fuccefs, in any one inftance. 



From a folution of platina, carefully neutralized, as Mr. 

 Chenevix directs, with red oxide of mercury, and mixed with 

 a folution of green fulphate of iron, I indeed obtained fuch a 



■ 



* The change of colour above defcribed, though certainly un- 

 common, is neverthelefs not peculiar to the falts of palladium, but 

 may be feen alfo in fome kinds of tourmalin. " Among thofe which 

 come to us from Ceylon, fome are tranfparent; and one variety is 

 of a deep red in the direction of its axis, but of a yellowifh green 

 .when viewed tranfverfely. There is alfo a correfponding, but op- 

 pofite contraft of colours, that has been obferved by Muller, and 

 defcribed by Bergmann, in fome of the Tyrolefe tourmalins. The 

 general afpect of thefe ftones is black, and apparently opaque. — 

 Some, however, of which the fracture is vitreous, are found to 

 tranfmit a yellowilh-red light when viewed tranfverfely, but in the 

 direction of their axis the colour is a dull bottle green. 



In each of thefe tourmalins, as well as in the falts of palladium, 

 • the colour in the direction of the axis is at leatl ten times more intenfe 

 than in the tranfverfe direction. A thin lamina, cut from the end 

 of a Tyrolefe tourmalin for thispurpofe, tranfmitted novifible light, 

 till it was reduced to -^ of an inch in thicknefs; and, when lefs 

 than T -I^. of an inch, it was not more tranfparent -than another 

 portion of the fame cryftal feen tranfverfely, ^% of an inch in thick- 



nefs. 



precipitate 



