122 
to the practical knowledge and ability of 
our countrymen, that in the good city of 
Paris, the focus of all the talent of 
France, it should be found necessary to 
engage Englishmen, for directors, and 
managers of their, gas-works! But it 
is not, my intention, in the present in- 
stance, to make, invidious comparisons 
between the practical talent of the two 
nations. Iam an advocate for the most 
unlimited interchange between the two 
countries, not onlyin speculative science, 
but in all the useful-arts. And I fully 
agree with you, Mr. Editor, that both 
mations: would derive incalculable ad- 
vantage from the unrestricted inter- 
course that will result from a repeal of 
the present absurd laws regarding the 
exportation of machinery, and the ex- 
patriation of working mechanics. These 
matters ought tu be always left to find 
their own level. 
As you justly state in your last num- 
ber, the subject of gas-lighting is at pre- 
sent one of very considerable import- 
ance; and .the more its principles be- 
come. understood, the more highly it 
will be appreciated. It has already ar- 
rived at a point of perfection in England 
which forms a most important feature in 
civileconomy. _As a measure of police, 
it has produced the best effects in our 
streets; and for artificial lights, in the 
jnterior of houses, its greater safety, 
convenience, and ultimate economy, are 
‘now so well understood, as to render it 
superfluous to offer any remarks on 
that head. I shall, therefore, with your 
permission, ayail myself of a column 
or two of your yaluable miscellany, to 
enter into a brief examination of the 
relative advantages of gas made from 
coal, and that made from oil, Having 
no interest whatever to gratify in the 
question, my enquiries have been di- 
rected to the subject merely as an inte- 
resting department of science ; my state- 
ments, therefore, if they be not alto- 
gether conclusive, will at least be im- 
partial. 
I shall not follow the system of the 
writer in the Revue Encyclopédique of 
giving a history of the progress of the 
Invention; considering it would, be a 
waste of your valuable pages, when 
several treatises have been already pub- 
lished on.the subject. But these works 
have been limited to the question of 
coal-gas manufacture only; whilst the 
competition that is likely to exist, by 
the establishment of oil-gas works, not 
only in the metropolis, but in many of 
the great towns of the kingdom, renders 
Comparative Value of Coal and Oil Gas. 
(Serr. 1, 
it desirable to have a clear view of the 
comparative value of oil gas and coal 
gas, both as to the economy of produc- 
tion, and the value of each gas in illu- 
minating power. 
With respect to the first point; the 
cost of production, I shall be extremely 
brief. For the projectors and managers 
of gas-works -are ~presumed to be per- 
fectly well acquaimted ‘both with the 
nature of the process, and the amount 
or value of the product ; but with regard 
to the comparative illuminating power 
of the two kinds of gas, there is great 
diversity of opinion, even between some 
of the most scientific men of the day. 
In the manufacture of gas, the first 
consideration is, The price of the raw 
material ; 2d. The expense of manufac- 
ture. In the first point of view, coal 
possesses the most decided ‘advantages 
over oil; whilst in the manufacture, in- 
cluding, the original expense of the ne- 
cessary apparatus, oil has greatly the 
advantage over coal. The only proper 
view of the question, however, is, which 
commodity affords the greatest quantity 
of gas, or rather affords the greatest 
quantity of light, in proportion to the 
original cost of the raw material ? 
In answering this question, I shall 
take the published accounts of the dif- 
ferent companies as authority for my 
calculations. 
It requires, on an average, about three 
bushels of the best Newcastle coals to 
produce 1,000 feet of good purified gas. 
Whilst it requires about ten gallons of 
good whale or cod oil to’ produce an 
equal quantity of oil-gas. Now if we 
take the price of coals consumed in the 
distillation at three shillings, and that 
of the oil at twenty shillings, coal ap- 
pears to be more economical than oil, 
in the ratio of 63. 
There is, moreover, a residuum of 
coke, tar, &c., after the production of 
coal-gas, equal to about two-thirds of 
the value of the original coals consumed. 
While the distillation of oil leaves no 
residuum of the smallest value. — By this 
mode of estimate, therefore, it would 
appear .that coal is more economical 
than oil in the proportion nearly 10-1, 
taking bulk for bulk of the gas pro- 
duced. 
But the cost of production in capital 
and labour in manufacturing coal-gas, 
being at least double that of oil-gas ; 
whilst the value of oil-gas in illuminat- 
ing power, is greater than that of coal 
gas, the advantages of the two commo- 
dities are, to a certain degree, counter- 
balanced. 
