OF PALLADIUM AND PLATINUM. 
283 
Of the Ammonia-chlorides of Palladium. 
It is well known that on adding water of ammonia to a solution of chloride of pal- 
ladium, a pink-coloured precipitate is produced, which by boiling dissolves, giving a 
brownish yellow liquor, from which on cooling a crystalline yellow substance sepa- 
rates. These two bodies have the same per cent, composition, expressed by the formula 
Pd Cl -f- N H 3 . Of this I need not detail any evidence, as it has been fully established 
by the labours of Berzelius, and quite recently by the experiments of Fehling. 
By means of an excess of ammonia, the pink red precipitate which first forms may 
be totally redissolved, giving a colourless solution, from which by evaporation, a salt 
is deposited on cooling, in colourless rectangular prisms. The existence of this salt 
has been long known, and as its analysis has been recently published by Fehling, 
I need not detail any of my own experimental results, which fully coincide with his. 
The formula of this body is Pd Cl + 2 N H 3 + H O, or rationally, according to the 
principles I have elsewhere laid down for the copper salts, N II 4 . Cl + Pd O . N H 3 . 
When gently heated it evolves water and ammonia, and leaves the yellow substance 
Pd Cl + N H 3 . The same decomposition may be effected by evaporating its solu- 
tion to dryness, in which case the yellow salt generally crystallizes in cubes. Were 
it not hazardous to draw any inference with regard to the isomorphism of bodies be- 
longing to the regular system, I should notice this fact as illustrative of the equiva- 
lency of Pd Cl . N H 3 with K. By a very cautious application of heat to the colour- 
less crystallized salt, some water may be expelled before the ammonia begins to come 
off, but I have never succeeded in rendering it quite anhydrous. It however partially 
assumes the formula N FI 4 . Cl + Pd.N H 2 , to which we shall find the ammonia- 
sulphate of palladium to present an equivalent. 
By the action of solutions of caustic potash on solutions of these ammonia-chlorides 
of palladium, a variety of products are formed, according to the proportions employed 
and the circumstances of temperature. For the complete investigation of these bo- 
dies I have not yet accumulated materials, but the results which have been already 
obtained are not without interest as indicative of the analogies of palladium to other 
metals whose laws of combination are better known. I shall consequently describe 
those substances I have as yet examined, although I intend to resume and extend 
their investigation before long. 
A. When the pink -red precipitate is boiled with a large quantity of water it dis- 
solves, and on cooling but little of the isomeric yellow salt crystallizes out. On adding 
to the brownish yellow liquor so obtained a solution of caustic potash not in excess, 
a yellowish precipitate falls, which by boiling becomes brown red, and distinctly 
crystalline. If the pink red substance (Pd Cl + NH 3 ) be dissolved in the hot water 
without much boiling, there is generally no precipitate on adding the caustic potash, 
and the solution is merely yellow, not brownish coloured. It appears necessary 
that, by the boiling, partial decomposition should occur, and some ammonia be ex- 
2 o 2 
