CHEMICAL HISTORY AND APPLICATION OP GUN-COTTON. 
71 
against this a considerable diminution in the cost of the apparatus used for directing the 
rays where they are wanted. The working expense consists of the coals burnt, the char¬ 
coal points used up, and the wear of the machinery, all of which perhaps scarcely ex¬ 
ceeds the cost of oil under the old system. The magnets are said rather to increase in 
strength than to diminish by use. The salary of an engineer is a more serious item, but 
the expense may be greatly reduced by appointing one engineer to several lighthouses, 
if the electric system become common. Mr. Holmes estimates the working expenses of 
the electric apparatus as compared with the oil lamp, at about 400 against 290. The 
French estimate is, “ Abstracting the expenses of the first establishment, it will be found 
that while the expenses of the annual maintenance of a lighthouse of the first order fed 
with colza oil rise to 9421 francs 75 centimes, those of the same lighthouse illuminated 
by electricity would be 12,240 francs.” Again, “ The annual expense will be increased 
29 per cent, in lighthouses of the first order, but it will have the effect of rendering the 
luminous intensity at least fivefold greater.” 
It has been objected that the light is too bright, dazzling the mariner and misleading 
him as to its distance, but experience will soon removelhis source of error ; and it is hard 
to understand how the light can produce any dazzling effect, unless exhibited at the head 
of a pier close alongside of which the mariner must steer his way. But for harbour 
lights it is not required. Its proper place is on the prominent points of the coast which are 
used as landfalls by vessels, and unless objections present themselves in the future which 
are as yet unknown, we may confidently anticipate that each of these headlands will in 
time be marked by its brilliant electric light .—Quarterly Journal of Science. 
ON THE CHEMICAL HISTORY AND APPLICATION OF GUN-COTTON. 
Delivered at the Boyal Institution of Great Britain, on Friday, April 15, 1864. 
BY PROFESSOR ABEL, F.R.S., DIRECTOR OF THE CHEMICAL ESTABLISHMENT OF THE WAR 
DEPARTMENT. 
The history of gun-cotton affords an interesting illustration of the facility with which 
the full development of a discovery may be retarded, if not altogether arrested for a time, 
by hasty attempts to apply it to practical purposes, before its nature has been sufficiently 
studied and determined. 
When Schonbein, in the autumn of 1846, announced that he had discovered a new 
explosive compound, which he believed would prove a substitute for gunpowder, the 
statement attracted general attention, and attempts were made with little delay in dif¬ 
ferent countries to apply the material to purposes for which gunpowder hitherto had 
been alone used. Schonbein, and Bottger (who appears to have discovered gun-cotton 
independently, shortly after the former had produced it) lost little time in submitting 
their discovery to the German Confederation ; and a committee was appointed for its 
investigation, by whom gun-cotton w r as eventually pronounced inapplicable as a substi¬ 
tute for gunpowder. 
In this country, gun-cotton was experimented with immediately after the method of its 
preparation was published by Schonbein. Researches were instituted into its nature, 
preparation, etc., by Porrett and Teschemacher, John Taylor, Gladstone and others. A 
few experiments were made on its application as a propelling and mining agent, and the 
manufacture of the material upon a considerable scale was set on foot by Messrs. Hall, 
the well-known gunpowder makers at Faversham ; a patent having been previously taken 
out in this country for the production of gun-cotton according to Schonbein’s process. 
This factory had, however, not been long in operation before a very disastrous explosion 
occurred at the works, by which a number of men lost their lives, and which was ascribed 
to the spontaneous ignition of the gun-cotton, by the jury, who endeavoured to in¬ 
vestigate its cause. From that time, the manufacture of gun-cotton upon any consider¬ 
able scale was abandoned in England, and no important contributions to our knowledge 
of this material were made, until, in 1854, Iladow published the results of some valuable 
investigations, which served to furnish a far more definite knowledge regarding the true 
constitution and proper method of producing gun-cotton, than had hitherto existed. 
