158 On Ozone and its Relations to 
which the direct cause may be traced to this principle, in 
others it offers the best explanation as to the reactions of 
substances on each other. The behaviour of finely di- 
vided platinum, known as “spongy platinum” on a mix- 
ture of hydrogen gas and atmospheric air or oxygen gas 
is an instance in question. In the voltaic action of an acid 
on an oxidizable metal influenced by the presence and 
contact of another less oxidizable metallic body. Fermenta- 
tion, the germ of decay and organic decomposition, mias- 
mata and aromas, may even be comprehended by the same 
hypothesis. It is only necessary to disseminate the inactive 
principle, the neutral body, in the presence of certain other 
substances capable of being affected by it, and the resulting 
action takes place, leaving the inactive principle intact for 
future generation. But this property is more remarkable, 
and, perhaps, most practically useful, in the action of animal 
charcoal or soluble organic matter. 
An alcoholic solution of gum guiacum should be effected 
in the following manner :—4} oz. of pure solid gum in ten 
ozs. of alcohol, sp. gr. °830, four ozs. of distilled water to be 
added, which ought not to precipitate the gum. If such 
should take place, or should the mixture assume a turbid 
appearance, more alcohol must be added to render the 
solution clear, and the clear liquid decanted in stoppered 
bottles, and wnxerposed to light. The test thus prepared is 
for the detection of ozone or zascent oxygen, the substance 
containing which under experiment for it should show a 
neutral reaction to test paper. 
One hundred grains of fresh burnt animal charcoal may 
be now plaeed ina test tube; on to it a quantity of the 
test liquid is poured so as to about quarter fill the vessel, 
by stopping the aperture and slowly turning the tube over 
to expose the charcoal alternately to the air, and then 
covering it with the liquid contents of the tube, and repeat- 
ing the operation about a dozen or more times, a slight 
but decided change of colour of the test liquid will become 
perceptible; in some instances a longer time is necessary 
to indicate the same effect. Gum guiacum in a powdered 
state is of a nearly white tint when first pulverized, but on 
exposure to the air soon assumes a green hue. It possesses 
a strong affinity for uncombined or nascent oxygen in par- 
ticular, becoming discoloured from its normal condition to 
a purple or deep blue when in combination with it. The 
alkaline permanganates and chlorates yield an equivalent 
of oxygen in contact with the gum, both being a solution, 
