V. ON PLAIINA, 125 



platina then takes place even without the application of heat, 

 but only after the fpace of fome days. 



The fupernatant fluid of the reduced platina, when heated, The fupernatant 

 acquires a. lilac colour, which becomes blue on long expofure f.^'^f^a*^^ *^ 

 to air, depofiting at laft a greenifli fubftance, refembling that 

 hitherto treated of. Oxigenized muriatic acid favours the 

 reparation of this fubftance. 



Sulphuretted hidrogen may alfo be employed for feparating Sulphuretted hi- 

 the platina from the red triple muriate ; the platina becomes fe- drogen aho fepa- 

 parated in the form of a brown powder ; the other metallic fub- 

 liance remains undiflurbed in the folution. It may, however, al- 

 moft totally be precipitated by liquid ammonia. The precipitate 

 obtained is brown. When fufed with potafii in a filver cru- 

 cible, the mafs acquires a green colour : On pouring muriatic 

 acid on it, no complete folution could be effe6ted ; there al- 

 ways remained a powdery fediment which refitted likewife 

 the adion of nitro-rauriatic acid. Carbonate of potafli fepa- 

 rated from this folution a fmall quantity of iron. The clear 

 fluid from which the iron had been feparated, remained per- 

 fectly tranfparent when heated ; but it aqquired a bluifli hue, 

 which increafed on concentration, and after the exficcation of 

 the fait. On adding a little nitric acid to the fait, the blue 

 colour became changed into a dark red. 



CONCLUSION. 



I now flatter myfelf with having proved, by the above experl- Conclufion., 



ments, that the red coloured triple falts of platina owe their The red colour 



colour to the prefence of a peculiar racial, oxidized to a cer- " ^^'"^ toapc- 



, culiar oxide, 



tarn degree. 



That this metal is nearly wholly infoluble In acids; that it nearly infoluble 

 becomes foluble in combination with platina; that when ox-'" ^'^'.'^^' ""'^^^ 

 idized, it appears in the form of a blue oxide inclining to green; platina. See, 

 that its oxides, when combined with platina, are foluble in al- 

 calies ; that its acid folutions are not decompofable by fulphu- 

 retted hidrogen ; that it imparts no colour to borax ; that its 

 oxides are reducible and volatilizable by heat, which vo- 

 latilization becomes favoured by a flreara of oxigen gas ; 

 and, iaftiy, that oxigen gas, aflifled by heat, is capable of 

 oxidizing this metal, and of volatiliidng it in the form of a blue 

 oxide. 



Thcfe 



