12if 



ON PLATINA. 



which is not green, hut yellow. This precipitate on being again 

 difTolved in muriatic acid, and faturated with carbonate of foda, 

 yields no farther green fubftance. 

 The green pre- I mingled a quantity of this green fubftance with vitrified 



itate was re- 



d fbv heat borate of foda, and expofed the mixture for twenty-five mi- 

 vrith borax) to a nutes in a double crucible to the moft intenfe heat I could pro- 

 white brittle -^ ji^g j.g|-^[^ ^^j ^ ^l^jjg j^j.jmg jnetal, which was difficultly 



metal j ' ... r ^ ■ • 



difficultly a(fted a6led upon by nitro-muriatic acid. The weak folution which 

 on by nitro-ra. },ad been obtained by this acid, had a violet colour; it yielded, 

 * on being evaporated, a dark, green refidue, which was foluble 



in muriatic acid, wnth which it formed a green fluid, 

 morefo when On pulverizing another quantity of this white brittle metal, 



powdered. ^^^ ^^^^ expofing it to the a6lion of nitro-murjatic acid, the 



folution was effeded more eafily, it was now more concen- 

 trated, and of a reddiQi-yellow colour. Muriate of ammonia 

 let fall into it, threw down a little brownifli-red precipitate, 

 a proof that this metal (till contained platina. 

 The folution of A quantity of the before-mentioned green fubftance being 

 the green lu - fUf^yiyed jn muriatic acid, acquired a yellow ifli colour on be- 



ftance became _ . . 



yellowifti byfal- ing mingled with fulphureous acid, or with a folution of green 

 piiureous acid or n^^riate of iron. Oxigenized muriate of Hme reftored the 



green muriate or . . ° 



iron. ofigmal green colour. « 



Ox. mur, of j^ thjfd part of the green fiibftance, on being expofed to 



_jpg„^ a violent heat in a, porcelain retort, yielded a blackith-blue 



The green fub- fublimate : the unfublimed part was a metallic fubttance, very 

 bW fablimate, ^'^cultly foluble in nitro-muriatic acid. 



and left metal. A fourth portion of the green fubftance was urged, in a 

 ^^f^'^^J^^^^^'J"^ crucible head, with nitrate of potaHi. After the decompofi- 

 heated with tion of the nitrate had been completed, the mafs was dif- 

 "■'^'■"=/'"'^'=^/''^fufed through water. The alkaline folution was colourlefs, 



was decompolcd. ■.,,, , p,..^, _ 



The alkali was and acids produced no change ot colour ui it. The refidue, 

 diflblved in wa- after repeated ablutions, was hardly aded upon by acids, the 



ter, andnot ., . . ., ^ . , in, ■ ■ 



changed by nitro-munatic acid not excepted. 1 his experiment precludes 



acids, the prefence of chrome and molybdena. 



not aded on by ^' '^ poffible to feparate nearly all the platina which is con- 

 acids, tained in the red triple muriate, by the mere admixture of al- 

 rnTmob'bdTna ''"''°'' ^^^ ^''^ fubfequent addition of dry potafh or foda; for 

 were abfent. doing this much heat is evolved, and the redudion of platina 

 Sepiration of ^^^^^^ ^^^^ ^jj^^^ inftantly. The fame may be efFeded by 



the platina from r , r 



the triple muri- means ol carbonate of potaQi or (oda ; but in that cafe the fo- 

 atc by alcohol, luiion mull be highly concentrated. The redudion of the 



platina 



