•tQQ ON PLATINA, 



When platina is Having fo far proceeded, I made a folution of platina in 

 diffoived in n. nitro-muriatic acid (the platina had been freed from iron as 

 m. acid, a black j^ ^^ poffible by muriatic acid.) During this folution, a 

 powder IS fepa- ,,, ,'i r i-i i 



rated. glittering black powder became leparated, as is always the 



cafe when platina of commerce is diflblved' in nitro-muriatic 



acid. If the operator be careful in collefling this powder as 



faft as it is feparated, the quantity which may be collefted, 



amounts to about 0,03 of the platina employed. But if this 



powder be not removed as faft as it is depofiled in the folution, 



part of it becomes again aded upon, and a much lefs quantity 



is obtained. 



Muriate of pi. The muriate of platina obtained, after having been fuflered 



was decompofed {q repofe and being decanted, I decompofed by adding by a 



monia. ' ' faturated folution of muriate of ammonia; the precipitate was 



feparated by decanting the fupernatant fluid, and repeatedly 



waflied till the water which pafled, did not become green by 



t\]e adc|ition of pruffiate of potafh. The precipitate obtained 



Tell'jw precipl- was of a ydloiv colour. The decanted fluid from which the 



•-^^e. precipitate had been feparated, and the firft quantity of water 



employed for its ablution, after having been mingled together 



The decanted ^^^ concentrated by evaporation to one third of its bulk, were 



fluid being con- again mixed with a folution of muriate of ammonia; the pre- 



centrate , an cipjiatg ^ow obtained was of a dark red colour. On treating 

 more muriate or r & 



amm. added, a the fluid feparated from it, as before, the precipitate which did 



dark red precipi- f^u j^^y^ ^^^ ^f ^ ^^,,/^ ^,,^jy,j_ ^,1 ^,^g{-g ^ifFerent CO- 



tate was obtain- . . •' ^ , ,, , ■ , 



ed. loured precipitates were caretully waflied till they contained no 



The fluid a veftige of copper or iron. 



decanted gave by ^ have remarked that if the folution of platina be flowly pre- 

 mur. amm. a pared, that is to fay, if the platina be introduced into the 

 precip. nitro-muriatic acid, in fmall quantities at a time, and the fub- 



The colour of fequent folution of each quantity be refpe6tively feparated, and 

 piatmTis'da'rkef f'^ps'^ately be decompofed by muriate of ammonia, the colour 

 the more of the of the precipitate or triple fait obtained, is darker in propor- 

 black powder ^jq^ ^^ ^^^ quantity of the black powder which was contained 

 in the lolution. . , ^ , . 



m the folution. 



The black pow- This black powder which is depofited during the folution of 



dens (difficultly) platina of commerce* in nitro-muriatic acid, is fohible (though 

 ioluble in nilr. ,.^ , , , . . . . . , ^ , ^ 



m. acid; and dilticultly) in nitro-munatic acid, compofed of much nitric, 

 dccomp. by mur. and little muriatic acid; its folution is alfo decompofable by 



* This black powder is likewife feparated during the folution of 

 titalleahle platina in nitro-muriatic acid. F. A. 



muriate 



1 



