There has lately been held, at No. 31 Lombard Street, London, a private
exhibition of the Holmes and Burke primary galvanic battery. The chief
object of the display was to demonstrate its suitability for the
lighting of railway trains, but at the same time means were provided
to show it in connection with ordinary domestic illumination, as it is
evident that a battery will serve equally as well for the latter as for
the former purpose. Already the great Northern express leaving London at
5:30 P.M. is lighted by this means, and satisfactory experiments have
been made upon the South-western line, while the inventors give a long
list of other companies to which experimental plant is to be supplied.
The battery shown, in Lombard Street consisted of fifteen cells arranged
in three boxes of five cells each. Each box measured about 18 in. by
12 in. by 10 in., and weighed from 75 lb. to 100 lb. The electromotive
force of each cell was 1.8 volts and its internal resistance from 1/40
to 1/50 of an ohm, consequently the battery exhibited had, under the
must favorable circumstances, a difference of potential of 27 volts at
its poles, and a resistance of 0.3 ohm.
When connected to a group of ten Swan lamps of five candle power,
requiring a difference of potential of 20 volts, it raised them to vivid
incandescence, considerably above their nominal capacity, but it failed
to supply eighteen lamps of the same kind satisfactorily, showing that
its working capacity lay somewhere between the two. A more powerful lamp
is used in the railway carriages, but as there was only one erected it
was impossible to judge of the number that a battery of the size shown
would feed. _Engineering_ says the trial, however, demonstrated that
great quantities of current were being continuously evolved, and if,
as we understood, the production can be maintained constant for about
twenty-four hours without attention, the new battery marks a distinct
step in this kind of electric lighting. Of the construction of the
battery we unfortunately can say but little, as the patents are not yet
completed, but we may state that the solid elements are zinc and
carbon, and that the novelty lies in the liquid, and in the ingenious
arrangement for supplying and withdrawing it.
Ordinarily one charge of liquid will serve for twenty-four hours
working, but this, of course, is entirely determined by the space
provided for it. It is sold at sevenpence a gallon, and each gallon is
sufficient, we are informed, to drive a cell while it generates 800
ampere hours of current, or, taking the electromotive force at 1.8
volts, it represents (800 x 1.8) / 746 = 1.93 horse-power hours. The
cost of the zinc is stated to be 35 per cent. of that of the fluid,
although it is difficult to see how this can be, for one horse-power
requires the consumption of 895.2 grammes of zinc per hour, or 1.96 lb.,
and this at 18_l_. per ton, would cost 1.93 pence per pound, or 3.8
pence per horse-power hour. This added to 3.6 pence for the fluid, would
give a total of 7.4 pence per horse-power per hour, and assuming twenty
lamps of ten candle power to be fed per horse-power, the cost would be
about one-third of a penny per hour per lamp.
Mr Holmes admits his statement of the consumption of zinc does not agree
with what might be theoretically expected but he bases it upon the
result of his experiments in the Pullman train, which place the cost at
one farthing per hour per light. At the same time he does not profess
that the battery can compete in the matter of cost with mechanically
generated currents on a large scale, but he offers it as a convenient
means of obtaining the electric light in places where a steam engine or
a gas engine is inadmissible, as in a private house, and where the cost
of driving a dynamo machine is raised abnormally high by reason of a
special attendant having to be paid to look after it.
But he has another scheme for the reduction of the cost, to which we
have not yet alluded, and of which we can say but little, as the details
are not at present available for publication. The battery gives off
fumes which can be condensed into a nitrogenous substance, valuable, it
is stated, as a manure, while the zinc salts in the spent liquid can be
recovered and returned to useful purposes. How far this is practicable
it is at present impossible to say, but at any rate the idea represents
a step in the right direction, and if the electricians can follow the
example of the gas manufacturers and obtain a revenue from the residuals
of galvanic batteries, they will greatly improve their commercial
position. There is nothing impossible in the idea, and neither is it
altogether novel, although the way of carrying it out may be. In 1848,
Staite, one of the early enthusiasts in electric lighting, patented a
series of batteries from which he proposed to recover sulphate, nitrate,
and chloride of zinc, but we never heard that he obtained any success.
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