286 
DR. KANE ON THE CHEMICAL HISTORY 
This empirical formula assumes more interest when rationally expressed : it be- 
comes Pd Cl + 3 Pd O + N H 3 + 3 H O. It therefore consists of the ordinary 
oxychloride, with an atom of ammonia in place of one atom of its water of hydra- 
tion, or it may be written Pd Cl . N H 3 + 3 (Pd O . H O), being- a compound of 
ammonia-chloride and hydrated oxide. But it is more consonant to analogy to con- 
sider it as containing a metallic amidide, and its formula is then written Pd Cl 
+ 2 . Pd O + Pd . N H 2 + 4 H O. It is thus the perfect analogue to the yellow 
powder produced by the action of water on the white precipitate of mercury, except 
that like all the copper and palladium bodies, it is hydrated, whilst the corresponding 
mercurial compounds are anhydrous. Such I consider to be the real constitution of 
this olive powder, and by our knowledge of its existence we are enabled to view the 
other ammonia-chlorides of palladium more intimately than previously had been pos- 
sible. Thus the change of the pink ammonia-chloride to the yellow must, as I con- 
ceive, be attended with an alteration in the mode of combination of its elements. 
The pink body is formed only by the direct union of ammonia with chloride of pal- 
ladium. It appears to be truly and simply Pd Cl + N H 3 ; but the yellow crystal- 
line substance is produced only by processes in which the palladium has certainly 
passed, at least in a great degree, from union with chlorine, and has combined with 
oxygen or amidogene. It is hence most probable that the yellow substance cannot 
also be simply Pd Cl + N H 3 . The arrangement of its elements may be expressed by 
the formula H Cl + Pd . N H 2 , or else there may exist for palladium a compound ana- 
logous to the mercurial white precipitate, its formula being Pd Cl + Pd N H 2 , and this 
combined with sal-ammoniac may form the yellow substance, precisely as the true 
white precipitate (Hg Cl + Hg . Ad) by union with sal-ammoniac forms Wohler’s 
white precipitate, the composition of which, as I have elsewhere shown, is expressed 
by the simple formula Hg Cl + N H 3 . 
C. By boiling a solution of the colourless crystalline ammonia-chloride of palla- 
dium (Pd Cl + 2 N II 3 + H O) with caustic potash in excess, for a long time, an 
olive-green powder falls, which when heated deflagrates like loose gunpowder. A 
quantity of it which I had prepared for analysis and incautiously heated, was thus 
lost, and I can therefore merely indicate the existence of this body, and defer the 
exact account of it to a future time. 
In the memoir already often alluded to, Fehling has noticed that, on dissolving 
the pink ammonia-chloride in boiling water, a small quantity of a brown powder is 
sometimes left undissolved, and on analysing it (determining only the content of 
metal and chlorine), he deduced that it had the formula Pd 3 Cl + 3 NH 3 . He re- 
marks, however, that the origin of a body having that formula, is under the circum- 
stances incomprehensible ; it indeed assumes the existence of a peculiar chloride of 
palladium for which there is no other evidence whatsoever. I have on two occasions 
