Acetylene, the Principles of Its Generation and Use | Page 7

in looking after the generating plant.
Where a gas-engine supplied from public gas-mains is used for driving
the dynamo, electric lighting can be had at a relatively small
expenditure for attendance on the generating plant. But the cost of the
gas consumed will be high, and actually light could be obtained directly
from the gas by means of incandescent mantles at far loss cost than by
consuming the gas in a motor for the indirect production of light by
means of electric current. Therefore electric lighting, if adopted under
these conditions, must be preferred to gas lighting from considerations
which are deemed to outweigh those of a much higher cost, and
acetylene does not present so great advantages over coal-gas as to
affect the choice of electric lighting. But in the cases where there is no
public gas-supply, and current must be generated from coal or coke or
oil consumed on the spot, the cost of the skilled labour required to look
after either a boiler, steam-engine and dynamo, or a power gas-plant
and gas-engine or oil- engine and dynamo, will be so heavy that unless
the capacity of the installation is very great, acetylene will almost
certainly prove a cheaper and more convenient method of obtaining
light. The attention required by an acetylene installation, such as a
country house of upwards of thirty rooms would want, is limited to one
or two hours' labour per diem at any convenient time during daylight.
Moreover, the attendant need not be highly paid, as he will not have
required an engineman's training, as will the attendant on an electric
lighting plant. The latter, too, must be present throughout the hours
when light is wanted unless a heavy expenditure has been incurred on
accumulators. Furthermore, the capital outlay on generating plant will
be very much less for acetylene than for electric lighting. General
considerations such as these lead to the conclusion that in almost all
country districts in this country a house or institution could be lighted
more cheaply by means of acetylene than by electricity. In the tabular
statement of comparative costs of different modes of lighting, electric
lighting has been included only on the basis of a fixed cost per unit, as
owing to the very varied cost of generating current by small
installations in different parts of the country it would be futile to
attempt to give the cost of electric lighting on any other basis, such as
the prime cost of coal or coke in a particular district. Where current is
supplied by a public electricity- supply undertaking, the cost per unit is

known, and the comparative costs of electric light and acetylene can be
arrived at with tolerable precision. It has not been thought necessary to
include in the tabular statement electric arc-lamps, as they are only
suitable for the lighting of large spaces, where the steadiness and
uniformity of the illumination are of secondary importance. Under such
conditions, it may be stated parenthetically, the electric arc-light is
much less costly than acetylene lighting would be, but it is now in
many places being superseded by high-pressure gas or oil incandescent
lights, which are steady and generally more economical than the arc
light.
The illuminant which acetylene is best fitted to supersede on the score
of convenience, cleanliness, and hygienic advantages is oil. By oil is
meant, in this connection, the ordinary burning petroleum, kerosene, or
paraffin oil, obtained by distilling and refining various natural oils and
shales, found in many countries, of which the United States (principally
Pennsylvania), Russia (the Caucasus chiefly), and Scotland are
practically the only ones which supply considerable quantities for use
in Great Britain. Attempts are often made to claim superiority for
particular grades of these oils, but it may be at once stated that so for as
actual yield of light is concerned, the same weight of any of the
commercial oils will give practically the same result. Hence in the
comparative statement of the cost of different methods of lighting, oil
will be taken at the cheapest rate at which it could ordinarily be
obtained, including delivery charges, at a country house, when bought
by the barrel. This rate at the present time is about ninepence per gallon.
A higher price may be paid for grades of mineral oil reputed to be safer
or to give a "brighter" or "clearer" light; but as the quantity of light
depends mainly upon the care and attention bestowed on the burner and
glass fittings of the lamp, and partly upon the employment of a suitable
wick, while the safety of each lamp depends at least as much upon the
design of that lamp, and the accuracy with which the wick fits the
burner tube, as upon the temperature at which the oil "flashes," the
extra