420 Dr. Wollaston on a new Metal , 
The colour of the solution that remains after the precipitation 
of platina, varies, not only according to its state of dilution, but 
also according to the strength and proportions of the nitric and 
muriatic acids employed. This colour, though principally owing 
to the quantity of iron contained in it, arises also in part from a 
small quantity of the ammoniaco-muriate of platina, that neces- 
sarily remains dissolved, and from other metals contained in 
still smaller proportions. 
(A. 1.) To recover the remaining platina, as well as to 
separate the other metals that are present from the iron, I 
have in some experiments employed zinc, in others iron, for 
their precipitation. The former appears preferable ; but, when 
the latter has been used, the precipitate may immediately be 
freed from the iron that adheres to it, by muriatic acid, without 
the loss of any of those metals which are at present the subject 
of inquiry. 
(A 2.) Having in one instance dissolved such a precipitate 
in nitro-muriatic acid, and precipitated the platina by sal am- 
moniac, I suffered the remaining fluid to evaporate without heat ; 
and obtained a mixture of various crystals, very different from 
each other in form and colour. From these, I selected for exa- 
mination some that were of a deep red colour, partly in thin 
plates adhering to the sides of the vessel, and partly in the form 
of square prisms having a rectangular termination. 
(A3.) A portion of these crystals being heated in a small 
tube, yielded sal ammoniac by sublimation, and left a black 
residuum, which, by greater heat, acquired a brilliant metallic 
whiteness, but could not be fused under the blowpipe. Having 
obtained this substance from a distinctly crystallized salt, I was 
inclined to consider it as a simple metal ; and, as I found it to 
