172 ARTIFICIAL ILLUMINATION, 
great advantage it at present has over electric lighting on the point of 
economy. 
The future of gas lies, however, not only in the direction of lighting, 
but also in its extended use as a heating agent and as a source of 
power. Already it is far the cheapest, cleanest and most manageable 
fuel for cooking, and it is making such rapid strides as a source of 
motive power that, in the opinion of the best judges, the gas engine is 
destined to be the engine of the future. 
The matter of the residual products of gas making is an important 
feature. The products of one ton of coal carbonised by a gas company 
are approximately 10,000 cubic feet of gas, 10 gallons of tar, 25 to 30 
gallons of ammoniacal liquor, and 12% cwt. of coke. From the tar 
and ammoniacal liquor no less than 44 different substances are now 
extracted which are invaluable in medicine, in the arts and manu- 
factures, and inagriculture. They include many of the most valuable 
dyes, anti-septics, and fertilisers, andare as useful as the gas itself, and 
it is considered that the cessation of the production of these articles 
would be infinitely more serious than the stoppage of the gas supply. 
Apart from lighting, therefore, the future of the gas industry 
is assured, and it must endure as long as workable bituminous coal- 
fields exist. Should the London Gas Companies succeed in the 
effort which they are now making to influence the Board of Trade 
to sanction the reduction of the illuminating standard of gas from 
16 to 14 candles, the great expense now attending the enrichment 
of the gas necessary to give it the extra 2 candle power above the 
natural value of about 14 candles will be saved, and gas companies will 
be able to largely reduce the price to the consumer without seriously 
impairing the illuminating power. This should result in an enormous 
stimulus to the use of gas for cooking, heating, and motive power, and 
might even lead to the displacing of coal in generating stations for 
electric lighting. Sir William Siemens used to say that it was a 
scandalous waste to burn bituminous coal as we do in our fire-places 
and furnaces, so much of the valuable products passing away unburnt 
to poison the atmosphere and lower the vitality of the inhabitants of 
our great cities, and giving that pestilential and destructive character 
to the fogs which envelop us in dirt and darkuess. Sir William 
Siemens was, of course, right. All bituminous coal should be separated 
into its gaseous and other parts, and each applied separately to its special 
purpose. No doubt, in the near future, the laws governing our health 
will be more generally appreciated than they are now, and, under the 
stimulus of a benevolent legislature, this will be carried out, and we may 
even look forward to the time when dwellers in towns will enjoy a 
pure atmosphere, subject only to colourless fogs as harmless as the 
mist of the mountain, and will live in houses and work in factories 
comfortably warmed and ventilated by gas; brilliantly lighted by gas 
on the incandescent system or by electricity generated by gas engines, 
while they will enjoy good food cooked by gas in spotless kitchens 
where the tradition of the smutty and wasteful coal ranges of former 
years will be a reminiscence of an ignorant and barbarous past. 
