OF PiiLLADIUM AND PLATINUM. 
281 
C. 138-397 grains were fused in a porcelain crucible and kept at a full red heat 
until all effervescence from loss of chlorine ceased. When cold it weighed 11 O' 185 
grains, equivalent to 8CP41 per cent. 
These results fully prove that the loss of chlorine which the protochloride under- 
goes when kept for some time fused at a full red heat, is perfectly definite ; and also 
that the loss represents one-half of the chlorine which the salt contains. Thus, 
by theory Pd 2 = 106‘6 produce Pd 2 = 106-6 
Cl 2 = 70'8 produce Cl = 35‘4 
177’4 142-0 
or 80-05 per cent. The substance formed is a true subchloride analogous to calomel, 
or to subchloride of copper, and its formula is Pd 2 Cl. 
The fused mass obtained by the methods now described, is of a deep red brown 
colour, and highly crystalline in structure. Its powder is light red. It deliquesces 
rapidly, and becomes dark -coloured from the separation of metallic palladium and 
the formation of protochloride. This change is effected almost instantly by contact 
with water, or solutions of sal-ammoniac, or iodide of potassium, also by water of 
ammonia. It is, however, not all decomposed; the quantity of metallic palladium 
which separates, I have found to be but from one-fifth to one-sixth of that which the 
subchloride contained. The liquor formed contains, therefore, both the subchloride 
and the protochloride dissolved together. The action of reagents on this liquor, 
however, does not differ materially from that produced with solutions of the proto- 
chloride. The liquor is much darker coloured than a solution of protochloride of 
the same strength should be, and is rendered turbid by dilution with more water. 
The first action of ammonia appears to be, the formation of a white compound, which 
is however almost instantly broken up into the pinkish ammonia-protochloride, and 
metallic palladium. 
In the double salts formed by the protochloride of palladium with the chlorides of 
the alkaline metals, I have found the similarity of constitution so usual between the 
compounds of ammonium and potassium to be violated. The double chloride of 
palladium and potassium has been fully shown by Berzelius to have the formula 
Pd . Cl + K . Cl, and not to contain any water of crystallization ; but the double 
chloride of palladium and ammonium retains an atom of water when crystallized. I 
examined a quantity of this salt which had formed long rectangular prisms of an 
olive colour with a rich bronze lustre. They were quite free from any foreign impu- 
rities. When heated, they yielded water, muriatic acid, sal-ammoniac, and left me- 
tallic palladium. 
By a very cautious application of heat the water may be completely expelled. 
From many experiments its quantity was found to be from 5'52 to 5‘95 per cent., 
2 o 
MDCCCXLII. 
