6Q MALLEABLE PLATINA. 



platina, and amalgamate them logelher; an(TTb"^ni7s amalgam 

 may be added alternate fmall quantities of platina and mercurj 

 till the whole of" the two metals are combined. Several pounds 

 may be thus amalgamated in a few hours, and in the large way 

 a proper mill might fliorten the operation. 



6. Mould the 6. After the amalgam is completely produced, it muft be 

 amalgam into quickly moulded in bars or plates, or any other forms that may 

 foon become ^^ preferred; taking care that thefe moulded pieces fliould at 

 ^'^^'*^' leaft be half an inch in thicknefs, and of a proper length to 



manage them afterwards in the fire; it is alfo requifite that 

 the moulds fliould be perfe^^ly even and fmooth. Half an hour 

 after the pieces are formed they begin to harden by the oxi- 

 dation of the mercury, and change their brilliant metallic co» 

 lour for a dull leaden one. 



7. Expel the 7. As foon as the pieces have acquired a proper degree of 



mercury, by ig- hardnefs to be handled without danger of breaking^, which 

 nition : i 1 1 • 1 • 1 • 1 , 



commonly takes place in a htlle more than an hour, place them 



in a proper furnace, and keep them ignited under a muffle or 

 in a fmall reverberatory. No other precaution is neceflary in 

 this operation but that of not breaking the pieces during their 

 Laftly, tranfporl. The mercury flies off during the heat, and the pla- 



"on iv'anf "^"^'"^ remains perfedly folid ; fo that, after being ftrongly ig- 

 forge or laminate nited two or three times before the bellows, it may be forged 

 ^^' or laminated in the fame manner as gold or filver; care being 



taken, at the commencement of the forging or of palling it 

 between rollers, not to apply too great a force till the metal has 

 Tofave tlie acquired all its deniity. It r . almoft fuperfluous to add that in 

 mercury on a evaporating the mercury from large quantities of amalgam, a 

 proper apparatus, fuch as in the filver amalgamation, muft be 

 employed to receive the volatiIize,d mercury; but for fmall 

 quantities, where the lofs of this metal is of no confequence, 

 the furnace muft have a proper chimney to carry off the metal- 

 lic vapours. When the platina comes out of the firft fire its 

 dimenfions are about two thirteenth parts fmaller every way 

 Remarkson this than the original amalgam from the mould. The wholeof this 

 procefs. operation feems to be governed by the preffure of the atmof- 



phere and the laws of cohefive attradion: for the air is driven 

 out from between the molecules of the platina, which by their 

 folulion in mercury are moft probably in their primitive and 

 confequently uniform figure. It is very vifible and at the 

 fame time a very amuftng phenomenon to obferve,, (during the 



procefs 



