100 
ON LIQUID FUEL. 
the blood-vessels, the bowel, though it may have been completely emptied by a dose of 
oil, may quickly again become tilled with morbid secretions, and hence the need for ail 
occasional repetition of the evacuant dose. If the diarrhoea be associated with vomiting, 
this should be encouraged and assisted by copious draughts of tepid water. The vomit¬ 
ing affords relief, partly by the stimulus which it gives to the circulation, but mainly by 
the speedy ejection of morbid secretions. If there be nausea without vomiting, and, 
more especially, if the stomach be supposed to contain undigested or unwholesome 
food or morbid secretions, an emetic may be given—either a teaspoonful of powdered 
mustard, or a tablespoonful of common salt, or 20 grains of ipecacuanha powder, in 
warm water. In all cases of severe diarrhoea the patient should remain in bed.”— 
British Medical Journal. 
ON LIQUID FUEL. 
BY BENJAMIN II. PAUL, ESQ. 
(,Substance of a Lecture delivered before the Society of Arts.) 
The economy of fuel is a subject of so much importance in a variety of aspects, and 
it affords so much scope for improvement, that any suggestion made with that object is 
always deserving of full consideration ; and, even if such suggestions should be imprac¬ 
ticable or erroneous, it is at least worth while to demonstrate clearly the circumstances 
which may be considered as justifying an adverse opinion. That such a course is appro¬ 
priate in regard to a project which is expected to involve a reconstruction of our navy 
and a radical revolution in steam navigation, will, I apprehend, be readily admitted. 
The proposal to substitute for the coal now used as fuel in steam-vessels some kind 
of liquid combustible, is an off-snoot of the excitement which has prevailed during the 
last few years in regard to the discovery of vast quantities of petroleum in America ; 
and it was that material which was in the first instance recommended as the substitute 
for coal. A commission appointed in America some years ago to investigate the subject 
reported that petroleum was beyond doubt more than twice as effective as anthracite 
coal in the production of steam, and that steam could, by the use of this material, be 
produced in less than half the usual time. 
It was an inference by no means unnatural that if this were the case, and if coal could 
be superseded by this material as the fuel of steam-vessels, a very great portion of the 
space required in merchant steamers for the stowage of coal would be rendered available 
for more profitable cargo ; that steam-packets might become independent of coal depots 
at various points of their passage ; and that vessels of war would be enabled to keep the 
sea for a very much longer time than they now do with coal. Any prospect of such 
advantages as these being attainable might reasonably have been expected to justify a 
more thorough and searching investigation of this subject than it has yet received in 
this country. 
Besides petroleum, several other analogous materials have been proposed as substitutes 
for coal; for instance, the oil obtained by distilling particular kinds of coal, or the shale 
which occurs in coal formations, and more recently the oil known as “dead oil,” which 
is one of the products obtained in rectifying the coal-tar of gas-works. All these ma¬ 
terials resemble each other closely in being composed chiefly of carbon and hydrogen, 
which are, in various proportions, the combustible and heat-producing constituents of all 
kinds of fuel. For the application of these materials and of liquid fuel generally, 
.various methods have been proposed ; but before speaking of them it is desirable to con¬ 
sider what is the evaporative power of these materials respectively, since that is a very 
important point to determine in regard to the question as to the relative merits of these 
different kinds of fuel. 
The heat generated by combustion has been made the subject of the most careful in¬ 
vestigation ; and since the time of Lavoisier, Laplace, and Rumford, the more precise 
measurement of the amounts of heat capable of being produced by the combustion of 
carbon and hydrogen, has been repeated by several physicists with results which agree so 
closely, that they may be safely regarded as well established. The names of Dulong, 
Despretz, Andrews, Favre, and Silbermann are, moreover, an unquestionable guarantee 
that these results, and the methods by which they were obtained, are perfectly trust¬ 
worthy. According to these results, the maximum heat-producing capabilities of carbon 
„gnd hydrogen are in the ratio of 1 to 4’5. The actual quantities of heat generated by 
•ihe combustion of a pound of carbon or of hydrogen are as follows:— 
