The Sun.
London, England, 1866-05-05 00:00:00

Royal Institution.

At the weekly meeting of the members of the Royal
Institution yesterday evening, Professor Abel delivered a
lecture on " Recent Progress in the History of Proposed
Substitutes for Gunpowder." Notwithstanding the many
substitutes hitherto proposed, gunpowder still maintains
its position as the best of explosive compounds for the
various uses to which it is applied. Its component parts
remain the same as when originally invented, for nothing
has been found to answer the purpose better than a mixture
of charcoal, saltpetre, and sulphur. Improvements have,
however, been made in the proportions of those substances,
and in the mode of manufacture, so as to render the ex-
plosive action more or less rapid, according to the various
objects for which it is used. For small arms and for shells
a rapid action is required, hut for !ergo ordnance and for
blasting a much slower combustion is necessary to produce
the required effects. Professor Abel exemplified the diffe-
rent degrees of rapidity with which various samples of
gunpowder explode, from the slow smoking kind, continued
to bo used by the Chinese, to the almost instantaneous ex-
plosion of the fine-grained powder used for small arms.
He explained the action of gunpowder to depend on the
rapidity of the supply of oxygen for the ombustion of the
charcoal. In saltpetre the oxygen is closely combined
with potass, and it requires a certain force and time to
rend them asunder. The sulphur is added to facilitate
the combustion, and he showed how much more
slowly the combustion of charcoal takes place
when it is mixed with saltpetre only than when
sulphur is added. Professor Abel mentioned numerous
substances that had been tried as substitutes for charcoal
and for saltpetre, including tanning, sawdust, and chloride
of potass, and exhibited the explosive effects of such com-
pounds, to all of which there are objections that pre-
vent their general adoption. He also explained the
methods that had been tried to render gunpowder less
dangerous when stored in magazines, such as mixing it
with powdered glass, and keeping the ingredients apart
until the time they were wanted, and he showed the im-
practicability of all such expedients. One of the recently
proposed substitutes for gunpowder was nitro-glycerine,
which explodes by percussion, and the dangerous nature
of which, he said, had been proved by a disastrous explo-
sion at Aspinwall. After having mentioned some other
proposed substitutes, Professor Abel proceeded to notice
gun-cotton, and to state some of the improvements that
have been made in its manufacture during the last two
years. He showed various specimens of it, and pointed
out the important differences that are effected by mecha
nical compression in various way, so as to enable it to
explode more or less:rapidly as required. Two pieces of the
slime weight, about three grains each, were exhibited, one
of which had been tightly compressed, the other remain-
ing fibrous, and the instantaneous explosion of the for-
mer was contrasted with the comparatively slow action
of thelatter. Gun-cotton, indeed, seems to be susceptible
of being made to suit all explosive purposes, and it pos-
sesses the great advantage of producing no smoke and of
leaving no residuum. Another advantage of no lessim-
portance is the safety with which it may be manufactured
and stored, for it can be wetted and rendered incombus-
tible, and its explosive properties are restored without in-
jury when dried. Some doubts have recently been enter-
tained IF Austria, where the great improvements in gun-
cotton •eFere first made, whether it is not injured by keeping.;
but Professor Abel considers that when manufactured with
properly prepared cotton there is little fear of its deprecia-
tion, and his experience at Woolwich, where the manu-
facture has been conducted on a large scale, leads him to
believe that gun cotton can be kept for years without in-
jury to its properties. Among other applications of whicL
gun-cotton is susceptible is that of fireworks, which might
be exhibited in a room without nuisance, and he concluded
the lecture, which was illustrated with numerous experi-
ments, by giving a brilliant pyrotechnic display.

PRODUCE OF THE COLONIES.—A Parliamentary
return shows that in the year 1865 10,250,524 cwt.
of unrefined sugar were imported into the United King-
dom, and 9,878,933 cwt. were retained for consumption—
viz., 5,002,326 cwt. from British possessions and 4,876,607
owt. of foreign sugar. The net revenue from sugar of all
sorts was X 5,193,816. The import into the United King-
dom of rum from British possessions advanced in 1865 to
6,478,494 gallons; the import of coffee to 112,321,2781 b.;
of cocoa to 4,793,8641 b. 465,778,8801 b. of cotton wool
were imported from British possessions. Of this quantity
14,485,6321 b. came from the Bahamas ; how that got to the
Bahamas may be easily guessed. The import of cotton
wool from India fell in 1865 to tt3,877,0881b.