534 
THE RAPIDITY OF DETONATION 
at CIRCUMSTANCE of singular interest has recently 
been revealed in connection with the investigations 
still being carried on with gun-cotton at Woolwich Ar- 
senal. The experiments made with this powerful explo- 
sive have now extended over a period of ten years, and 
although many discoveries of vital interest have been 
made by Professor Abel and by Mr. E. O. Brown, who is 
aiding in the research, the results teach us, before every- 
thing, how much more we have yet to learn of the pro- 
perties of pyroxilin. First of all, the violence of its 
explosion had to be tamed, then a compressed form of 
the material was devised, and after that it was shown 
that, like its sister-explosive, nitro-glycerine, gun-cotton 
could be violently detonated, if ignited by a charge of 
fulminate. Gun-cotton, in fact, turns out to be sympa- 
thetic, for, according to the energy with which it is in- 
flamed, so it responds in its behaviour: thus, if gently 
ignited by a spark, the cotton, in the form of yarn, smoul- 
dered slowly away ; when set fire to by a flame, it burnt 
up rapidly ; if in the form of a charge it was exploded in 
a mine or a fire-arm, it at once resented the shock and 
replied with corresponding energy, behaving like gun- 
powder under similar circumstances ; while, lastly, if fired 
with great violence with a few grains of fulminate, it is 
detonated with as much force and with the same terrible 
effect as its instigator. 
More recently, as many may have heard, our inves- 
tigators have succeeded in detonating, or, in other words, 
exploding to the best advantage, gun-cotton when in a 
damp condition ; and in this state the explosion is every 
bit as violent as when the material is dry. This grand 
discovery is naturally of the utmost importance, because, 
although many objections may be advanced as to the 
danger of storing and using gun-cotton when dry, the 
most nervous of us would scarcely hesitate to employ it 
sopping wet. In this latter condition the material is, 
strange to say, not only non-explosive, but positively non- 
inflammable ; so much so, indeed, that it would be probably 
as serviceable in putting out a fire as a wet blanket 
or a damp towel would be. It can neither be inflamed 
nor exploded when wet; and further, unless one has 
the key to its detonation—a little fulminate of mercury— 
it is of no more value as an explosive than so much wet 
paper pulp. When placed in contact, however, with a 
fuse of the proper construction and a cake of dry gun- 
cotton, to start the action, the wet pyroxiline, as we have 
said before, detonates as readily as when the moisture 
amounts to but a fraction of a percent. Moreover, the 
quantity of water in the material is really of no import- 
ance, for it has been found that for submarine mines, 
compressed cakes enclosed in a fishing-net and thrown 
overboard with a dry primer and a fulminate fuse, will 
explode with just as much energy as when confined in a 
water-tight steel case. 
It is in respect to this detonation, and more particularly 
to the rapidity of its action, that we desire to speak at the 
present moment. Recent experiment has shown that the 
rapidity with which gun-cotton detonates is altogether un- 
precedented, the swiftness of the action being truly mar- 
vellous. Indeed, with the exception of light and electricity, 
the detonation of gun-cotton travels faster than anything 
else we are cognizant of. Thus, detonation will run along 
a line of gun-cotton cakes, placed so as to touch one 
another. with a rapidity only inferior to that of electricity, 
setting fire to a charge or conveying a signal, if desired, 
almost instantaneously. Twenty thousand feet, or nearly 
three miles per second, is calculated to be its rate of 
travelling according to Noble’s electric chronoscope. In 
one experiment forty-two feet of the material was fired,and 
records secured at every six feet; and in this case the 
results given were most uniform, for the velocity only 
varied from nineteen to twenty thousand feet per second, 
the ratio of transit being in no instance less than this. 
NATURE 
[Oct. 23, 1873 
To form an approximate idea of this extraordinary 
rapidity, it is necessary to call to mind the rates of 
travelling of other mediums. Light and electricity we 
may leave out of the question, as these are immaterial 
bodies. A bullet usually flies at the rate of 1,300 feet 
per second, although rifled barrels have been known to 
project a shot with a velocity of 1,400 feet. Sound is 
much slower in travelling, for a second of time is required 
in getting through some I,100 feet. A quick match of the 
most delicate construction would probably be longer still 
in making way, and a train of gunpowder would be left 
far behind. So it may be safely affirmed, we think, that 
the detonation of gun-cotton travels more rapidly than 
any other known medium, with the exception, we repeat, — 
of light and electricity. 
It is curious to note that not every detonating or fulmi- 
nating substance will induce the detonation of gun-cotton, 
It seems as if a certain number of vibrations require to” 
be set up—a certain key-note to be struck—in order to 
secure the decomposition of the material. Thus it is 
found that fulminate of mercury detonates guncotton 
readily, while again it is also capable of being detonated 
by itself; so that if a line of compressed cakes is deto- 
nated at one end by a charge of fulminate of mercury, 
the detonation is communicated rapidly from one cake to 
another, until they are all consumed. Nor does the force — 
diminish at all as it runs along the line, as might perhaps 
be imagined ; if this were the case, the detonation set up 
at the beginning of a line would only run up to a certain 
distance, and there come to a full stop, as soon, that is, 
as the vibrations are insufficient to explode the gun-cotton. 
This, however, does not happen in actual experiment ; 
and, on reflection, it stands to reason that if the first cake 
of pyroxilin is capable of firing the second one, the 
ninety-ninth is just as ready to detonate the hundredth, 
Thus the detonation can be carried along a line of any 
length, and the force is as powerful and violent at the end 
as it was at the beginning. 
This property of gun-cotton may obviously be put to 
valuable use both in industrial and military operations. 
In any case where it is of importance that a-series of 
blasting or mining charges should be fired simultaneously, 
their connection together by means of gun-cotton would 
ensure such a result. True, the same effect could be 
obtained by means of an arrangement of insulated wires, 
the charges being detonated simultaneously with the aid 
of a battery, but such a plan is not always convenient 
nor practicable. For cutting down palisades, or stout 
wooden walls, a line of gun-cotton discs exploded in this 
way would be most efficacious ; and a more ready plan of 
felling timber does not probably exist than that of placing 
around the stem of a tree a chain or necklace of the ex- 
plosive in the form of compressed cakes, the detonation 
of these dividing the trunk as sharply as the keenest axe. 
NOTES 
WE read in the Daily News :—‘‘ Mr. Ilenry Cole, C.B., pre- 
sided at the annual meeting of the Hanley School of Art, on 
Monday evening, and after speaking of the results of the South 
Kensington Museum, said it was his painful duty to announce 
that this organisation, which had borne such great fruits, and 
which was so highly prized by the nation, and was so indispen- 
sable to the commercial and social progress of this country, was 
in jeopardy. The Government contemplated changes which 
were directly opposed to the further development of the Science 
and Art Department. It had hitherto flourished under a 
management which ensured individual Parliamentary responsi- 
bility, but it was now proposed to hand over South Kensington 
to the Trustees of the British Museum, who were already fully 
occupied in their own departments. The management of the 
British Museum was not such as to make them desirous of seeing’ 
