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4A Proceedings of the British Association. | . 
acid, potassa, and many oxysalts; dilute sulphuric acid yielding 
it in the greatest quantity, while no smell whatever was perceiv> 
ed on the decomposition of solutions of hydracids, chlorides, bro= ~ " 
mides, or iodides, which not only did not evolve it mselves, 
but by their presence, even in small quantity, prevented its evo- 
lution from solutions which would otherwise have produced it 
abundantly. He found, on collecting the oxygen gas evolved at 
the anode, from a solution capable of evolving the odor, that the 
odor might be preserved for some time, by enclosing the gas in” 
well-stopped bottles. From the characters possessed by this oxy- 
gen, he was led to consider the odor due to the presence of a 
minute quantity of anew and hitherto wholly unknown sub- 
stance, of considerable importance in many natural phenomena, 
and he has therefore named it from its most evident character, 
ozone. Its properties are briefly as follows: it is evolved only 
from solutions containing it, by perfectly clean electrodes of pla- 
tinum or gold; whilst charcoal and the more ‘oxidizable metals 
are unable to cause its appearance. It can be obtained only from 
a cold solution, as heat prevents its evolution. When a piece of 
one of the oxidizable metals, such as zinc, tin, iron, mercury, &c., 
or a few drops of solution of the protochloride of tin, or proto- 
sulphate of iron, are placed in a portion of oxygen impregnated 
with ozone, that peculiar substance is almost instantaneously ab- 
sorbed ; and the oxygen becomes inodorous. When perfectly 
clean and dry plates of gold or platinum are immersed in oxy- 
gen containing ozone, they acquire a negatively electric state of 
polarity: silver and copper also become thus electric, but in a far 
less degree than gold or platinum. The plates thus polarized re- 
tain their electric powers in air for a considerable time, but rapid- 
ly lose it when plunged into h drogen gas, in which, if retained 
a sufficient time, they acquire an opposite state, becoming posi- 
tively polarized. He then compares these effects with those pro- 
duced by the odorous matter peculiar to common electric sparks 
and brushes. When a perfectly clean and dry plate of gold or 
platinum is exposed to an electric brush issuing from a charged 
and conducting point, it becomes positively polarized, and the — 
degree of polarity depends on the nature of the point and the 
time which the plate has been exposed to the influence of the 
brush issuing from it. He shows that the power is not due to 
the mere current of electricity escaping from the point, but to 
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