of a metallic Substance called Palladium. 297 
the effect of muriatic acid upon its solutions ; as is lead, by that 
of the sulphuric. Tin, antimony, bismuth, or tellurium, would 
have left an insoluble residuum with nitric acid. No traces 
could be found of any of the acidifiable metals ; and iron was 
looked for with particular care, but in vain. In a word, the pre- 
cipitation by the metals, seems to exclude all those of easier 
oxidability than mercury ; and this we should not suppose to be 
present, as copper is not in the least whitened, when used to 
precipitate palladium. 
The striking similarity of many of the precipitates of palla- 
dium with those of platina, induced me to multiply the com- 
parative experiments; and I constantly observed contradictory 
facts. The specific gravity, easy fusibility, combination w r ith 
sulphur, precipitation by green sulphate of iron and by prussiate 
of potash, together with other effects, were such as I could not 
reconcile to the known characters of platina; unless I could 
suppose that a substance did exist, which could totally change 
its physical and chemical properties, or so disguise them as to 
render them proof against the evidence of chemical reagents. 
The lightest of the metals is tellurium ; yet, in order to pro- 
duce an alloy of the specific gravity of palladium, (supposing 
for a moment the real density of the alloy equal to the calcu- 
lated mean,) it would require two parts of tellurium and one of 
platina ; and it is highly improbable, that so large a proportion 
of tellurium could exist in any mass, without being detected. 
We have been told of very extraordinary anomalies in chemical 
affinities, by Mr. Berthollet; and Mr. Hatchett has made 
us acquainted with some, not less extraordinary, in the properties 
of alloys. Yet I think we shall cease to wonder at what has 
been related by these chemists, when we learn that palladium is 
