For the past ten or fifteen years the manufacture of ozone, for the
reasons related above, has remained in abeyance, and it is to a new
mode, which will, I trust, mark another stage of advancement, that I
now wish to direct attention. Some years since, Mr. Wimshurst, a most
able electrician, invented the electrical machine which goes by his
name. The machine, as will be seen from the specimen of it on the
table, looks something like the old electrical machine, but differs in
that there is no friction, and that the plates of glass with their
metal sectors, separated a little distance from each other, revolve,
when the handle of the machine is turned, in opposite directions. The
machine when it is in good working order (and it is very easily kept
in good working order) produces electricity abundantly, and in working
it I observed that ozone was so freely generated, that more than once
the air of my laboratory became charged with ozone to an oppressive
degree. The fact led me to use this machine for the production of
ozone on a large scale, in the following way.
From the terminals of the machine two wires are carried and are
conducted, by their terminals, to an ozone generator formed somewhat
after the manner of Siemens', but with this difference, that the
discharge is made through a series of fine points within the
cylinders. The machine is placed on a table with the ozone generator
at the back of it, and can be so arranged that with the turning of the
handle which works the machine a blast of air is carried through the
generator. Thus by one action electricity is generated, sparks are
discharged in the ozone generator, air is driven through, and ozone is
delivered over freely.
If it be wished to use pure oxygen instead of common air, nothing more
is required than to use compressed oxygen and to allow a gentle
current to pass through the ozone generator in place of air. For this
purpose Brin's compressed oxygen is the purest and best; but for
ordinary service atmospheric air is sufficient.[2]
[Footnote 2: For illustration to-day, Messrs Mayfield, the
electrical engineers of Queen Victoria Street, E. C., have been
good enough to lend me a machine fitted up on the plan named. It
works so effectively that I can make the ozone given off from it
detectable in every part of this large hall.]
The advantages of this apparatus are as follows:
1. With care it is always ready for use, and as no battery is required
nor anything more than the turning of a handle, any person can work
it.
2. It can be readily moved about from one part of a room or ward to
another part.
3. If required for the sick it can be wheeled near the bedside and, by
a tube, the ozone it emits can be brought into action in any way
desired by the physician.
I refer in the above to the minor uses of ozone by this method, but I
should add that it admits of application on a much grander scale. It
would now be quite easy in any public institution to have a room in
which a large compound Wimshurst could be worked with a gas engine,
and from which, with the additional apparatus named, ozone could be
distributed at pleasure into any part of the building. On a still
larger scale ozone could be supplied to towns by this method, as
suggested in Hygeiopolis, the model city.
It will occur, I doubt not, to the learned president of this section,
and to others of our common profession, that care will have to be
taken in the application of ozone that it be used with discretion.
This is true. It has been observed in regard to diseases, that in the
presence of some diseases ozone is absent in the atmosphere, but that
with other diseases ozone is present in abundance. During epidemics of
cholera, ozone is at a minimum. During other epidemics, like
influenza, it has been at a maximum. In our paper Dr. Moffatt and I
classified diseases under both conditions, and the difference must
never be forgotten, since in some diseases we might by the use of
ozone do mischief instead of good. Moreover, as my published
experiments have shown, prolonged inhalation of ozone produces
headache, coryza, soreness of the eyes, soreness of the throat,
general malaise, and all the symptoms of severe influenza cold.
Warm-blooded animals, also, exposed to it in full charge, suffer from
congestion of the lungs, which may prove rapidly fatal. With care,
however, these dangers are easily avoided, the point of practice being
never to charge the air with ozone too abundantly or too long.
A simple test affords good evidence as to presence of ozone. If into
twenty ounces of water there be put one ounce of starch and forty
grains of potassium iodide, and the whole be boiled together, a starch
will be made which can be used as a test for ozone. If ozone be passed
through this starch the potassium is oxidized, and the iodine, set
free, strikes a blue color with the starch. Or bibulous paper can be
dipped in the starch, dried and cut into slips, and these slips being
placed in the air will indicate when ozone is present. In disinfecting
or purifying the air of a room with ozone, there is no occasion to
stop until the test paper, by change of color, shows that the ozone
has done its work of destroying the organic matter which is the cause
of impurity or danger. For my own part, I have never seen the
slightest risk from the use of ozone in an impure air. The difficulty
has always been to obtain sufficient ozone to remove the impurity, and
it is this difficulty which I hope now to have conquered.--_The
Asclepiad._
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