^ Experiments on Tlatlna, 



Large grains of platina picked and healed, emit alfo an 

 odour of fulphur accompanied with fumes. A perfon em- 

 ployed by government to colleft platina informed me, that 

 the largeft grains he ever faw never exceeded the fize of a 

 pea; and that he had given feveral of that fize to the arch- 

 bifhop of Santa-Fe. In regard to the enormous grain faid 

 to be depofiled in the cabinet of Vergara, the dircdlor of the 

 Bifcayan fociety affured me that he had no knowledge of it. 



When crude platina is brought to a red heat in a covered 

 crucible, no odour of fnlphur is perceived with the vapour of 

 the charcoal, but at the moment when the crucible is unco- 

 vered this odour manifefts itfelf very powerfully; but if the 

 crucible be fhut clofe it ceafes. It was long before I was 

 able to difcover the nature of this vapour; but the experi- 

 ments, which will be defcribed hereafter, proved to me that 

 it is nothing elfe than concentrated fulphuric acid. 



From 1600 grains of white crude platina well purified, 

 and heated in a retort, I obtained only half a grain of mer- 

 cury and a grain and a, half of water, without any kind of 

 gas. Having broken the retort before it was quite cold, it 

 exhaled a fulphurous odour. The platina became black, 

 and was found (lightly cemented, and adhering to the glafs. 



A mixture of 400 grains of the fame crude platina and an 

 equal quantity of fweet muriate of mercury, healed in a re- 

 tort, gave, after the fublimation of the mercury, a very light 

 ftratum of cinnabar, which adhered to the top of the retort, 

 and, when fcraped a little, affumed a vermilion colour. 



Crude platina, heated in a crucible and immediately pourQ 

 into a filver difh, blackens the vefiel in the fame manne ^s 

 fulphur. In a word, all folutions of platina form an ?Jun- 

 dant precipitate with barytcs. 



As fulphurets of platina, both native and artificial ^'o ^^ot 

 fufFer their fulphur to efca^)e when heated in coveted veliels, 

 there is reafon to believe that this metal cannot be entirely 

 freed from it by an open fire ; for the fulphuret which occu- 

 pies the centre of each grain, may then be co^fi'lsred as ihut 

 up in a vefTel. 



Here, then, we have fulphur as a conf^'t^ient part of crude 

 platina. It may here l)e a{ked, with vnat combuftible this 

 fulphur is united. If it be recoUeacJ that iron, and even 

 copper, exifts alfo in this ore, it wi^ not be fuppofcd that it 

 is combined with the platina; ^•id yet it is with this metal 

 that the fulphur is united, as wH be feen hereafter. In the 

 mean time it may be deduc.;d, from the preceding experi- 

 ments, that what is at prefcnt called, and what ought to bo 

 coalinued to be called, crude flalinay is evidently nothing 



elle 



