Sxey.—Chemical Effects of Oxygenized Graphite. 347 
chlorine has a greater affinity for silver than for copper. There is no 
doubt, however, that the forming of this chloride of silver stops the action 
ata point at which we cannot readily distinguish that any action has taken 
place. 
Art. XLIX.—On certain Chemical Effects of Oxygenized Graphite and 
Platinum. By Wiiu1am Sxuy, Analyist to the Geological Survey of 
New Zealand. 
In the experimental results I am about shortly to describe, I do not for the 
present distinguish between graphite, etc., as combined with a compound of 
oxygen such as nitric acid, which easily gives up oxygen, or graphite, etc., 
as combined with oxygen alone, either as oxygen or ozone. 
In some of them it is most probable that this acid or a product of it, as 
absorbed by the graphite, operates for their production, while in others it 
really appears that it is oxygen which is the sole operant. 
But, as all these experiments were carried on in the presence of nitrogen, 
a gas which is, as we know, susceptible of being acted upon in certain cases 
by oxygen in such a manner that nitric or nitrous acids result ; and, further, 
nitric acid is, as I have long since shown, absorbed by charcoal, and also, 
as will presently appear, by graphite and platinum too, I cannot, therefore, 
as yet unreservedly attribute any of these results to the action of absorbed 
oxygen alone, although, as previously stated, I incline to this view. 
Having thus defined the position I would hold for the present in regard 
to the bearing of these results, I will at once state them. They are as fol- 
lows :— 
1st. That any surface of graphite, native or artificial, which has 
been for some time exposed to the air, liberates iodine from a 
solution of potassic iodide in weak sulphuric acid. 
2nd. That graphite, which can thus liberate iodine, loses this pro- 
perty when washed in ammoniacal or other alkaline solutions ; 
also by ignition. 
8rd. That this property of liberating iodine is restored to such graphite 
y a short exposure of it to the air ; or by evolving nascent hy- 
drogen against it; also by digesting it for a little while with 
hydrochloric or weak sulphuric acid, either at a common temp- 
erature, or at the boiling point of these acids respectively, 
4th. That graphite, which thus liberates iodine, also rapidly deter- 
mines a chemical effect upon mercury, when voltaically paired 
