280 
I)R. KANE ON THE CHEMICAL HISTORY 
Chlorides of Palladium. 
The properties of the ordinary protochloride of palladium have been for the most part 
so fully described by those chemists that have previously occupied themselves with the 
study of this metal, that I shall notice it but briefly. From a strong solution, it cry- 
stallizes in prismatic needles which are very deliquescent. These crystals were found 
to contain two atoms of water of crystallization, which they lose by a gentle heat. 
The action of a high temperature on protochloride of palladium developes some 
facts of considerable interest. It is not so reduced to the metallic state unless by 
very violent ignition, but just at a red heat it melts and begins to evolve chlorine, 
which continues until it has parted with one-half of that which it contains. The 
liquefied mass which remains is a true subchloride, which is not further acted upon, 
unless the heat be very much increased. 
The following numerical results will render this decomposition evident : — 
A. 29*881 grains of the crystallized protochloride being carefully dried as long as 
they gave off any traces of watery vapour were found to have lost 5*247 grains, or 
1 7’56 per cent. 
The dried mass was heated until it had completely fused. It was then dull red. 
In this state it was found to weigh 22*055 grains, having given off 2*577 grains of 
chlorine, or 8*63 per cent. 
T his was next kept melted at a bright red heat until it appeared to cease giving 
off any gas. It then weighed 19 , 632 grains, having lost in addition 2*423 grains, or 
8*1 1 per cent, of chlorine. 
This residue was now fully ignited with some carbonate of ammonia, until the 
metallic palladium remaining appeared to be quite pure ; this then weighed 14*554 
grains, or 48*71 per cent., the quantity of chlorine abandoned in this final stage 
having been 5*078 grains, or 16*99 per cent. 
The quantity of palladium and the total quantity of chlorine and water, show that 
the salt in its crystalline condition has the formula Pd Cl -f 2 H O, by which we have 
Theory. Experiment. 
Palladium . . 53*3 49*95 48*71 
Chlorine . . 35*4 33*18 33*73 
Water . . . 18*0 16*87 17’56 
106*7 100*00 100*00 
The relation between the proportions of chlorine which were evolved at the differ- 
ent periods, were as 8*11, 8*63, and 16 99. I do not attach much importance to the 
two first being so nearly equal, but to the fact that the quantity which was not ex- 
pelled by the heat was sensibly equal to half the total quantity in the salt. 
B. 58*919 grains of dried protochloride were heated in a porcelain crucible to full 
redness, until it fused without any disengagement of gas. The residual subchloride 
weighed 47*782 grains, or 81*13 per cent. 
