OF RENDERING PLATINA MALLEABLE. 7 



wire, determined by comparing the weight of a given length of it with the 

 weight of an equal length of gold Avire drawn through the same hole, I find 

 to be 21.5, which is the maximum specific gravity that we can well expect to 

 be given to platina. 



The mean tenacity, determined by the weights required to break them, of 

 two fine platina wires, the one of ^cV o? the other of ^^Vo of an inch in diameter, 

 reduced to the standard of a wire xVth of an inch in diameter, I found to be 

 409 pounds ; and the mean tenacity of 11 wires, beginning with ^f joir and end- 

 ing with j3-.0(j5 of an inch, reduced to the former standard, I found to be 589 

 pounds ; the maximum of these 1 1 cases being 645 pounds, and the minimum 

 480 pounds. The coarsest and the finest wire which I tried, present exceptions, 

 since a wire of tAtt of an inch gave 290 pounds, and a wire of ttj^cs of an 

 inch, 190 pounds. If we take 590 pounds, as determined by the 11 consecu- 

 tive trials, to be the measure of the tenacity of the platina prepared by the pro- 

 cesses above described, and consider that the tenacity of gold wire, reduced 

 to the same standard, is about 500, and that of iron-wire, 600, we shall have 

 Ml reason to be satisfied with the processes, detailed in the present paper, by 

 which Platina has been rendered malleable. 



To this paper I beg to subjoin an account of some processes relating to two 

 of the metals which are found in the ore of platina. 



To obtain malleable Palladium, the residuum obtained from burning the 

 prussiate of that metal is to be combined Avith sulphur, and each cake of the 

 sulphuret, after being fused, is to be finally purified by cupellation, in an open 

 crucible, with borax and a little nitre. The sulphuret is then to be roasted, at 

 alow red heat, on a flat brick, and pressed, when reduced to a pasty consistence, 

 into a square or oblong and perfectly flat cake. It is again to be roasted very 

 patiently, at a low red heat, until it becomes spongy on the surface. During 

 this process, sulphur flies off' in the state of sulphurous acid, especially at those 

 moments when the heat is allowed occasionally to subside. The ingot is then 

 to be cooled ; and when quite cold, is to be tapped with a light hammer, in 

 order to condense and beat down the spongy excrescences on its surface. The 

 alternate roastings and tappings (or gentle hammerings) require the utmost 



