Quarterly Scientific Intelligence [pp. 350-356]

Quarterly Scientific Intelligence.
minute the test will show the presence of ozone, and in five or
six hours it will be comparatively abundant. Remove the
phosphorus and wash out the acids. The ozone may be preserved by corking the bottle.
To prepare the test for ozone, take 1 part of pure iodide of
potassium, 10 parts of starch, and 200 parts of water, and boil
them together a few moments. This may be put on common
writing paper with a brush; or, by dipping bibulous paper into
the solution, we have Sch5nbein's ozometric test. The test when
moistened turns blue instantly in the presence of ozone, or if
exposed to a dry atmosphere, containing ozone, it becomes
blue on being moistened, in consequence of the evolution of
iodine.
By whichever method ozone is obtained it is identical. Its
principal properties are as follows:-It is a gaseous body of a
peculiar odor, which when concentrated resembles chlorine, but
when dilute it cannot be distinguished from what is called the
electric smell. It is irrespirable, producing catarrhal effects if
inhaled with the air, and killing small animals. Like chlorine
and bromine, and many per-oxyds, it is a powerful electromotive
substance. It discharges vegetable colours with a chlorinelike energy. It acts powerfully on most metallic bodies,
producing the highest degree of oxydation of which they are
capable. It produces oxydizing effects in. most organic compounds, causing a variety of chemical changes; thus guaiacum is
turned blue by it. From what has been said, it would seem to
be a most ready and powerful oxydizer, acting, in many cases,
like Thenard's per-oxyd of hydrogen, or chlorine, or bromine.
With respect to the nature of this body, the two principal
ideas are, that it is a compound of oxygen analogous to the peroxyd of hydrogen, or that it is oxygen in an allotropic state;
i. e. with the capability of immediate and ready action impressed
upon it. When an ozoneized atmosphere is made as dry as
possible, and sent through a red hot tube, the ozone disappears,
being converted apparently into common oxygen gas, and no
water or other result is produced. This agrees with the well
known fact that heat prevents the formation of ozone, and also
with the idea that ozone is only oxygen in an allotropic state.
IMeans of obtaining a Vacuum.-The Philosophical Magazine
for February contains an account of an ingenious mode, devised
by Dr. Thomas Andrews, of obtaining a vacuum in the receiver
of an air pump, not less perfect than the Torricellian vacuum,
which, though sufficiently perfect, is not generally available.
It is rare to find an air pump which will indicate a pressure
.1852.]
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