276 
DR. KANE ON THE CHEMICAL HISTORY 
Section I. — Palladium Compounds. 
Oxides of Palladium. 
It has been long established that palladium combines with oxygen, at least in two 
proportions, forming the protoxide , which is the basis of its ordinary salts, and the 
deutoxide, which appears to be analogous to the deutoxide of platinum, and to react 
in many cases as an acid. To this last body I have not hitherto directed much at- 
tention, but some properties of the protoxide which I have noticed appear not un- 
worthy of being described. 
The protoxide of palladium is best prepared by the decomposition of the protochlo- 
ride, by means of a solution of carbonate of soda in excess. The precipitate which 
first forms is light-coloured, but it soon becomes darker, carbonic acid gas is disen- 
gaged, and finally an ochrey brown powder falls, which, by drying, becomes dark 
brown. The precipitation is in this case by no means perfect, the liquor is coloured 
yellow by traces of the metal dissolved, and the precipitate retains with obstinacy 
traces of the alkali, from which, however, it may be freed by washing. 
When this substance is heated, it first evolves water and then oxygen, leaving a 
black powder, to the nature of which I shall recur. By a very high temperature (full 
white heat) it is totally reduced to the metallic state. 
The analyses of this hydrated oxide when first performed led to very irreconcile- 
able results, owing to two circumstances, — 1st, that the oxide of palladium is by no 
means so easily reduced to the metallic state by the mere agency of heat as has been 
supposed; and 2nd, that although the precipitation of the hydrated oxide is accom- 
panied with the disengagement of much carbonic acid, yet the precipitate always 
contains some traces of that acid ; it effervesces very distinctly when dissolved in 
dilute muriatic acid, and is in fact a highly basic carbonate of palladium, rather than 
a true hydrated protoxide. The following details of the experiments made as to its 
composition, will place these circumstances in evidence. 
A. 53*524 grains of a specimen which had been carefully washed until the liquors 
ceased to react alkaline, were gently heated over the flame of a spirit-lamp, until no 
more traces of water were evolved. The residue, a jet black powder, of anhydrous 
oxide, weighed 45*224 grains, or 84*49 per cent., having lost 15*51, apparently only 
water. 
B. 41*102 grains of another portion, similarly treated, gave a dry residue of 34*512 
grains, or 83*96 per cent. This was then heated to full redness, and when cold 
weighed 31*779 grains, or 77*32 per cent. 
C. 72*481 grains of a specimen prepared at another time gave, when dried until 
the last traces of water had been driven off, a black powder weighing 61*241 grains, 
or 84*49 per cent., and at exposure to a red heat was reduced to 56*131 grains, or 
77*45 per cent. 
D. 56*578 grains of a different specimen gave when dried 48 306 grains, or 85*38 
