OF PALLADIUM AND PLATINUM. 
279 
It is not impossible but this body may be in reality a mixture of a less basic carbonate, 
with the true hydrated oxide, but I consider that the remarkable constancy of compo- 
sition, indicated by so many specimens, prepared at different times, giving results so 
closely coinciding, argues very strongly in favour of its definite nature. It occurred to 
me also that the content in carbonic acid might arise from the presence of carbonate of 
soda,but I satisfied myself that although it is very difficult to obtain specimens which do 
not after ignition yield traces of alkali, yet it is never present in such quantity as could 
give the above results, when thefreshly precipitated substance has been properly washed. 
The properties of the suboxide of palladium, now first definitely found, are not 
very distinct. The existence of this suboxide had been long suspected, especially 
from the fact, that by heating to dull redness in contact with air, metallic palladium 
becomes coloured blue or green on the surface, which colours are removed by violent 
ignition. Berzelius found, however, that this colouring was not attended with any 
increase of weight, which arises, however, from the minute quantity of oxide formed, 
the colours being those of thin plates ; but there can be now no doubt but that for- 
mation of suboxide does so occur. That the black powder which is left by the dull 
ignition of the basic carbonate is really a definite compound, is strongly supported 
by the fact of the accuracy with which the decomposition stops at its formation, and 
by the analogy of the subchloride, to be hereafter described, it gains additional force. 
Yet I have not been able to combine in any way this suboxide with acids. By con- 
tact with them, it gives an ordinary salt of the protoxide and metal. It is possible, 
however, that in future trials I may be more successful. 
It is known that by the addition of a caustic fixed alkali to a salt of palladium a 
precipitate is obtained, which redissolves in a great excess of the alkali. The preci- 
pitate is in this case a basic salt, not the hydrated oxide, and always contains traces 
of the alkali, from which it is with difficulty freed by washing. The soluble alkaline 
compound cannot be obtained in a definite form by any process that I have as yet 
tried. By evaporation to dryness, the oxide separates anhydrous, and retaining a 
small quantity of alkali. 
When the basic carbonate of palladium (hydrated oxide) is diffused through water 
of ammonia, it partially dissolves, giving a brown powder and a yellow-coloured 
liquor, which when evaporated dries down to a bright yellow deliquescent mass. 
When heated, this decomposes with slight deflagration and copious disengagement 
of gas, leaving metallic palladium. The brown powder also contains ammonia, and 
when heated gives it off with water, and the metal is reduced. I can, however, at 
present only indicate the existence of these two bodies, as the analytical results which 
I have obtained respecting them are too discordant to admit of my assigning any 
definite formulae for their constitution. The soluble compound I conceive to arise 
from the ammonia acting on the carbonate, as it does on any other palladium salt, 
and the insoluble to be the product of the ammonia on the oxide which is present in 
excess. I reserve these bodies, therefore, as objects of future study. 
