S Procefs for rendering Platina malleable, 



Philofophical Magazine, it will meet the eyes of thofe for 

 whom it is intended. If any benefit refult from it to fcience, 

 or the arts, my end is gained, and I (hall feel amply repaid 

 for my trouble. The method I piirfue is as follows : — 



To a given quantity of crude platina. I add 15 times its 

 weight of nitro-muriatic acid (compofed of equal parts of 

 nitric and muriatic acids) in a tubulated glafs retort, with a 

 tubulated receiver adapted to it. It is then boiled, by means 

 of an Argand's lamp, till the acid has aflumed a deep faffron 

 colour: it is then poured off; and if any platina remains un- 

 diflblved, more acid is added, and it is again boiled until the 

 whole is taken up. The liquor, being fuffered to reft till 

 qiiite clear, is again decanted: a folution of fal-ammoniac 

 is then added, by little and little, till it no longer gives a 

 cloudinefs. By this means the platina is thrown down in 

 the form of a lemon-coloured precipitate, which having fub- 

 lided, the liquor is poured off, and the precipitate repeatedly 

 waflied with diftilled water till it ceafes to give an acid tafte; 

 (too much water is injurious, the precipitate being in a cer- 

 tain degree foluble in that liquid :) the water is then poured 

 off, and the precipitate evaporated to drvnefs. 



So far my procefs is in a great meafure fimilar to that 

 which fome others have alfo followed ; but my method of 

 managing the fubfequcnt, and which are indeed the principal 

 manipulations, will be found to poffefs many advantages 

 over any that has yet been made public. The beft procefs 

 hitherto followed has been, to give the precipitate a white 

 heat in a crucible, which in fome meafure agglutinates the 

 particles; and then to throw the mafs into a red-hot mortar, 

 or any fimilar implement, and endeavour to unite them by 

 iifing a peftle or ft;amper. But the mafs is fo fpongy that it 

 is hardly poflible to get a fingle ftroke applied to it before the 

 welding heat is gone ; and though by peculiar dexterity and 

 addrefs fome have in this way fucceeded, it has been found 

 to require fuch innumerable heatings and hammerincs, that 

 moft of thofe who have attempted it, have either failed en- 

 tirely, or given it up as being too laborious and expenfive. 

 I have fucceeded in obviating all thefe difficulties, by adopt- 

 ing the following fimple, eafy^ and expeditious method : — 



A flrong, 



