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 wire 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 yoW the other of s^Vo of an inch in diameter, 
reduced to the standard of a wire Toth of an inch in diameter, I found to be 
409 pounds ; and the mean tenacity of 1 1 -wires, beginning with tto o and end- 
ing with 2 j.noo 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 T joo of an inch gave 290 pounds, and a wire of joioo 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 
full 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 with 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 
a low 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 
