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113
In spite of adverse criticisms, the process has been a success for
•eight years.*
Hypochlorite of magnesium belongs to the magnesia and not to the
alkali group. It is not caustic, is non-poisonous, and to the clothes is the
least destructive of all the hypochlorites. It is obvious that the stable
solutions of electrolytically-made hypochlorites of magnesium are
preferable to those of sodium and potassium or even calcium, because
for the purposes of rendering the three last mentioned solutions stable
there would have to be used hydroxide of the metals of the alkali or the
alkaline earth calcium, which are extremely caustic, alkaline, and very
soluble, and where varying strengths of electrolytic fluid, containing the
hypochlorites of sodium and potassium, are produced, one may add too
much or too little of the hydroxides of the alkalies when working with
unskilled labour. But when the extremely insoluble hydroxide or
oxide of magnesium is added and mixed, one can add and stir in any
quantity, but only the necessary amount will be absorbed.
* In addition to the plants already supplied to the British War Office and Admiralty,
quite recently plants have been sent to Finland, Buenos Aires and Rangoon. The
Cateshead Municipal Corporation have also given an order for a plant to be erected, and
while this report is being written, a large plant is being installed for the Portsmouth
Corporation. It is interesting to note that in the last case, the fluid to be electrolysed is
sea-water itself which, of course, is close at hand, and a ready and powerful disinfectant
is manufactured by this process without cost of materials but merely that of electric
current.
One feels sure that, when this is generally known, without doubt, other seaside
towns will follow the example of Portsmouth, and afford an unlimited supply of a disinfectant
for municipal purposes for the benefit of the health of the townspeople and visitors.
Since the apparatus was first installed, eight years ago, many improvements have
been made which have been described in previous reports. Recently a very important
improvement has been introduced for the reception of the fluid from the electrolysers.
Instead of the glass receptacles, which are apt to break, and are very costly, specially
made cheap metal drums have been substituted.
Whilst this report is being written, a double cell has been constructed of slate, in
such a form that the "creeping" of the current (which comes direct from the Council's
mains) from one cell to another is prevented. This is a most important item. All slate
Contains metal, and the current in "creeping" from the electrodes in one cell to the
electrodes in the other cell causes erosion to take place, and sooner or later a "dead short"
happens, and a new double cell is required, which is an expense.
The present cells are earthenware, and replaced the original slate ones and were made
by a firm of potters in the Borough at the special request of the Medical Officer of Health
and under his direction and supervision, potters outside the Borough having refused to
make them as they stated the baking would be a failure. However, the tanks or cells
were made and as stated above are the present ones, having been in use for some years.
Electricity, on account of moisture, will even creep with an earthenware cell and efficiency
will be lost and if the partition of the earthenware cell or tank is not properly glazed it
•will in course of time become destroyed by the electrical current (240 volts and 20 amperes)
acting upon the fluid which soaks into the unglazed earthenware. Earthenware cells
take a long time to make (possibly four months), and one is never certain that in the firing
of earthenware there will not be defects in the articles when they are taken out of the
kilns. A slate double-cell can be made in a few days, is cheap, and as now constructed
will not permit the current to "creep" and erosion to take place, whereby we have
cheapness, safety and greater efficiency. The current being taken direct from the Council's
mains saving the expense of a "converter" w ith its consumption of current and necessary
skilled attention.