G02 
ON LIQUID FUEL. 
case some deduction required to be made for the steam applied as a blast to the fire, but 
the amount was not ascertained. This result was also obtained under peculiarly favour¬ 
able circumstances as regards the proportion of heating surface of the boiler to the rate 
of evaporation. 
In regard to the supply of material capable of being used as liquid fuel, it is necessary 
to make a few remarks. First, as regards petroleum, I imagine it is now generally ac¬ 
knowledged that this material in its natural state is not well adapted for the purpose. 
In that state it contains a large amount of very volatile hydrocarbon, which, even at the 
ordinary temperature, vaporizes by contact with air, and the mixture of this vapour with 
air is explosive. At the temperature of a steam vessel’s stokehole this vaporization 
would take place more readily, and if there were any leakage in the supply pipes or 
tanks, disastrous consequences might ensue. In order to remove this objection to the 
use of petroleum as liquid fuel, the more volatile portion of it must be separated by 
distillation, and that operation, when carried far enough to render the oil fit for use 
with safety, would reduce the quantity to about one-third. 
Another objection to petroleum in its natural state is its bulkiness, the gallon 
weighing only about 8 pounds. This is to some extent removed by the distillation, 
and by the reduction of the quantity to one-third an oil is obtained which weighs 
about pounds per gallon. 
According to the latest returns, the total production of petroleum in America— 
which is out of all proportion the most abundant source of this material—amounts 
to about 360,000 tons a year. It would be mere speculation to offer any opinion as 
to whether this rate of production is the maximum which is attainable, or as to the 
time it may continue; but the prevailing impression is that the sources from which 
this supply originates are subterranean accumulations, and, therefore, not to be de¬ 
pended on beyond a certain limit. The experience of oil-winning in America has 
confirmed this view, for it has been found that the wells which were at first what are 
termed “ flowing wells,” i. e. yielding their oil spontaneously, have gradually ceased to 
flow; and that after pumping has been resorted to for bringing the oil to the surface, 
even that means gradually declined in its effect. It would therefore be unwise to 
rely upon the supply of petroleum as affording material for fuel. And then, if we 
consider the vast consumption of coal for the purpose of steam navigation—amounting, 
I believe, to not less than 10,000,000 tons a year in steam vessels belonging to this 
country alone, it will be seen that the production of petroleum—gigantic as it is in rela¬ 
tion to the use to which it has been applied—is insignificent when compared with the 
requirements of steam navigation for fuel; that, in fact, the total production does not 
amount to 5 per cent, of the fuel consumed in the steam vessels of this country. 
The possibility of obtaining an oil analogous to petroleum by distilling certain kinds 
of coal and some varieties of bituminous shale, constitutes another source of liquid fuel, 
and one which I consider to be far more important, for this country at any rate, than 
petroleum is. The material obtained from this source, and commonly known as crude 
paraffin oil, requires to be submitted to the same operation as petroleum, in order to re¬ 
move the more volatile portion, and obtain an oil suitable for use as liquid fuel, but it 
would have the advantage of yielding rather a larger amount of such oil than petroleum 
does. To what extent the production of this oil might be developed as a source of sup¬ 
ply for steam navigation, it would be almost impossible to form any approximative idea 
at present; but I may state, in regard to this point, that owing to the low price at 
which petroleum is now imported from America, the coal and shale oil works of this 
country have been almost entirely stopped, because of their inability to manufacture oil 
for burning at such a price as to compete with the American product. Circumstances 
which it would be out of place to enter into here, induce me to believe that if the use 
of liquid fuel were introduced to any extent into practice, it would be a very great ad¬ 
vantage to the oil manufacturers of this country, and would be a means of enabling 
them to meet successfully the competition of the American oil used for burning in lamps. 
I have already spoken of the supply of “dead oil,” furnished by the rectification of coal- 
tar, and need here only remark again that the quantity is very small. This is certainly 
the most suitable material for use as liquid fuel which I am acquainted with, and its ex¬ 
cellence in this respect induces me to mention another possible source of a similar material, 
viz., the distillation of “slack,” or the waste coal-dust, which accumulates at the mouth 
of a coal-pit. It is quite possible that by such means a quantity of oil, similar to that 
