rendering Platina malleable. 103 



top, with a heavy hammer, so as at one heating effectually to 

 close the metal If in this process of forging, the cylinder 

 should become bent, it should on no account be hammered on 

 the side, by which treatment it would be cracked irremediably; 

 but must be straightened by blows upon the extremities, dex- 

 terously directed, so as to reduce to a straight line the parts 

 which project. 



The work of the operator is now so far complete, that the 

 ingot of platina may be reduced, by the processes of heating 

 and forging, like that of any other metal, to any form that 

 may be required. After forging, the ingot is to be cleaned 

 from the ferruginous scales which its surface is apt to contract 

 in the fire, by smearing over its surface with a moistened mix- 

 ture of equal parts by measure of crystallized borax and 

 common salt of tartar, which, when in fusion, is a ready solvent 

 of such impurities*, and then exposing it, upon a platina 

 tray, under an inverted pot, to the heat of a wind-furnace. 

 The ingot, on being taken out of the furnace, is immediately 

 to be plunged into dilute sulphuric acid, which in the course 

 of a few hours will entirely dissolve the flux adhering to the 

 surface. The ingot may then be flattened into leaf, drawn 

 into wire, or submitted to any of the processes of which the 

 most ductile metals are capable. 



The perfection of the methods above described, for giving 

 to platina complete malleability, will best be estimated by 

 comparing the metal thus obtained, in respect of its specific 

 gravity, with platina, which has undergone complete fusion ; 

 and by comparing it, in respect of its tenacity, with other 

 metals possessing that quality in the greatest perfection. 



* The chemist will find this flux very serviceable for removing from 

 his crucible or other vessels of platina those ferruginous scales with 

 which, after long use, and particularly after being strongly heated in a 

 coal or coke fire, they become incrusted. In the analysis of earthy mi- 

 nerals, I have been in the habit of using a similar flux, composed of two 

 parts by weight of crystallized carbonate of soda, and one of crystallized 

 borax, well ground together. It has the advantage of not acting, like 

 caustic alkali, upon the platina crucible, and is a powerful solvent of 

 jargon and many other minerals, which yield with difficulty to other 

 fluxes. If the mineral to be operated on requires oxidation, in order to 

 decompose it, a little nitre or nitrate of soda may be added. 



