Dr. Wollaston on the Discovery of Palladium. 319 
3dly. It is more usual for the prism to have eight sides by 
truncation of each of its angles, and at each extremity eight 
additional surfaces occupying the place of the eight linear 
angles between the prism and terminating pyramid of the 2d 
variety. The complete crystal has then thirty-two sides. 
4,thly. The eight surfaces last mentioned, as interposed 
between the prism and pyramid, are sometimes elongated into 
a complete acute pyramid having eight sides arising from the 
angles of an octahedral prism. 
The 3d form above described, corresponds so entirely with 
that given by the Abbe Hauy * as one of the forms of the 
hyacinth or jargon, that I have little reason to regret my inabi- 
lity to obtain chemical evidence of the composition of these 
crystals. 
Those, and other impurities, I usually separated, as far as 
was practicable, by mechanical means, previously to forming 
the solution of platina, which has been the principal object of 
my attention. 
§ III. Precipitation of Platina. 
When a considerable quantity of the ore had been dissolved, 
and I had obtained, in the form of a yellow triple salt, as much 
of the platina as could be precipitated by sal ammoniac, clean 
bars of iron were next immersed in the solution for the purpose 
of precipitating the remainder of the platina. 
For distinction it will be convenient to call this, which in fact 
consists of various metals, the first metallic precipitate. 
The treatment of this precipitate differed in no respect from 
that of the original ore. It was dissolved as before, and a portion 
* Traitc de Mineralogie, PI. XLI. fig. 17 . — Jo tun, dcs Mines , No. 26, fig. 9. 
