[ 238 ] [Book VI. 



CHAP. XXXVI. 



P L A T I N A. 



l Hi/lory ef ibis curious MftaL Its Properties. The moj? pon- 

 derous Body in Mature. Its Hardnefs and Infujlbility . Soluble only 

 in Aqua, Regia and oxygenated muriatic Add. Its Union with other- 

 Metals. Crucibles formed "of it.-~Migljt be applied to various Ufes 

 which no other Metal can anfwer. 



IN the beginning of the year 1749, the firft fpe- 

 cimen of this metal was brought into England 

 from Jamaica. It was faid to have been originally 

 brought from the Spanifh Weft Indies, and it is ftill 

 almoft exclufively found in the gold mines of Spanifh 

 America. It is brought over in the form of fmall 

 fmooth grains, jrregularly figured, with round edges, 

 and is often mixed with ferrugineous fand and grains 

 of quartz or cryftal. The grains of platina are whiter 

 than iron, but lefs fo than filver, and their flat form is 

 probably owing to the preffur'e they undergo in the 

 mills in which the gold is amalgamated. 



In confirmation of this opinion, fmall particles of 

 gold and mercury are ufually found mixed with the 

 grains of platina. In the ftate in which they are 

 brought over, they fall fhort of the weight of gold, 

 but by purification, which is performed by wafhing 

 with the muriatic acid, and by expofing them for a 

 long time to the heat of the moft violent furnaces, 

 which, however, are faid to be inefficient to melt them*, 



* This is the opinion of the generality of mineralogifts; but my 

 friend and ./chemical preceptor, Dr. Higgins, affixed me, he had 

 melted platina in his furnace. 



they 



