January 18, 1873.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
567 
ployment, though at present it appears doubtful whether 
they can enter into competition with the more violent 
•explosive agents which have within the last six years 
become formidable rivals of powder. 
Gun-cotton was gradually growing into extensive 
use, as a mining agent in England, within a year of its 
■discovery by Schonbein; but its application was ar¬ 
rested for many years by the explosion which occurred 
at Messrs. Hall’s works in 1847. Between that period 
and 1863, when its manufacture was resumed in Eng¬ 
land, the material was made the subject of elaborate ex¬ 
periment in Austria. Important improvements were 
eventually introduced in its production and purification 
by Baron von Lenk, and it was converted by him into a 
form decidedly better adapted for mining purposes than 
the gun-cotton wool, namely, that of a compact rope, 
having a central perforation, and cut into suitable 
lengths for mining charges. An extensive series of ex¬ 
periments, instituted in Austria with gun-cotton in this 
form, appeared satisfactorily to establish its superiority 
over gunpowder, bulk for bulk, as regards rending and 
shattering effects, when used in hard rock or when con¬ 
fined in strong cases. The absence of smoke, and the 
■considerable reduction in weight of the charge required 
to produce a particular result were also important ad¬ 
vantages, substantiated by the experiments of Sir Ed¬ 
ward Sabine’s Committee on Gun-cotton, and by the 
results of practical trials in this country. The benefits, 
in point of economy and efficiency, derived from the 
■employment of the rope-charges, were very greatly in¬ 
creased when the system was devised of reducing the 
gun-cotton fibre to pulp, and converting it by powerful 
compression into compact homogeneous masses, having 
about double the density of the rope. Important conse¬ 
quences of the large reduction in the space occupied by 
gun-cotton, when used in this form, were the very con¬ 
siderable increase in the amount of tamping which could 
be used in blast-holes, and the greater concentration of 
the force applied; the destructive effects in hard rock 
were consequently much augmented, and the blast-holes 
could be placed further apart, and reduced in dimensions. 
Large charges of compressed gun-cotton occupied so 
much less space than the rope-charges, and were so con¬ 
siderably lighter than powder-charges, that the material 
became specially valuable for submarine operations. 
Other peculiar advantages were presented by the com¬ 
pressed material; thus, its cost of production was 
greatly reduced, because cotton-waste could be em¬ 
ployed in its manufacture, and because its conversion 
into the required forms required comparatively little 
time ; its purification was more complete, a3 the finely- 
divided fibre was much more readily washed than the 
long fibre required for furnishing rope-charges ; and its 
uniformity was much greater, because the products of a 
large number of successive small operations were inti¬ 
mately blended together in the pulping and washing 
processes. 
One point of inferiority, exhibited by gun-cotton in 
the form of wool or rope, was not at first remedied, but 
nather increased by its conversion into compressed 
masses. This consisted in the necessity for very strong- 
confinement of the material, for the proper development 
of its explosive force. If used just like gunpowder, in 
rock which was soft or contained fissures, its destructive 
effects were very imperfect, and under these circum¬ 
stances very irritating and unwholesome vapours were 
produced by its ignition. Large charges used in mili¬ 
tary operations or for the removal of great masses of 
rock required to be confined in very strong receptacles. 
Hence, although -the use of compressed gun-cotton in 
•ordinary blasting and quarrying operations in hard rock 
soon began steadily to increase, and though its value for 
submarine operations was undoubted, it continued for 
some time to be uncertain in its effects when employed 
in a particular class of mining operations and when used 
for military engineering purposes. After it was found, 
however, that compressed gun-cotton could be ex¬ 
ploded through the agency of detonation, the metamor¬ 
phosis being thereby so rapidly transmitted throughout 
a mass as to render any confinement unnecessary, its 
application became extended to new and important pur¬ 
poses, and it became closely allied, in regard to the 
results which it furnished, to the companion explosive 
agent, nitro-glycerine, which has been raised within 
the last nine years from the obscure position of a useless 
chemical product to an exalted rank among practically 
useful explosive agents entirely through the labours of 
Mr. Alfred Nobel. 
In 1S63 Mr. Nobel first attcmplecl to apply nitro-gly¬ 
cerine by impregnating the grains of gunpowder with 
it, and igniting the mixture in the usual way. But this 
mode of proceeding being uncertain in its results, he 
concluded that the certainty of exploding nitro-gly¬ 
cerine would be increased if a small portion of the 
mass were raised by some special contrivance to the 
heat at which it would violently explode, the explosion 
being thereby transmitted through the entire mass. 
He suggested several devices for producing what he 
termed the initiative explosion of a portion of the 
charge, but the most simple and successful one con¬ 
sisted in the employment of a large percussion cap, by 
the explosion of which the adjacent particles of nitro¬ 
glycerine were suddenly exposed to a high temperature 
and to a sharp concussion. This was the first instance 
in which the violent explosion or detonation of com¬ 
pounds of this class, known not to explode violently un¬ 
less strongly confined, was accomplished through the 
agency of initiative detonation. Compressed gun-cotton 
was soon afterwards observed by Mr. Brown to behave 
similarly, and in the course of an investigation insti¬ 
tuted by Mr. Abel into these and other phenomena ex¬ 
hibited by explosive agents, this susceptibility to violent 
explosion, without the aid of confinement, through the 
agency of a detonation, wa3 found to be shared by all 
explosive compounds and mixtures, even including gun¬ 
powder, though the force and nature of the detonation 
required to develope the explosive metamorphosis dif¬ 
fered very considerably with different substances. Nu¬ 
merous interesting results were obtained which showed 
that the development of detonation was at any rate not 
simply due to the exposure of particles of the substance 
to a very high temperature or to the suddenness and 
violence of the concussion to which they were sub¬ 
mitted. 
Mr. Nobel’s discovery of a simple method of explod¬ 
ing nitro-glycerine placed this substance at once at 
the head of practically useful explosive agents in point 
of power; and the success with which he developed 
the manufacture of nitro-glycerine soon rendered this 
remarkable liquid available for extensive technical uses. 
Its value as an explosive agent for mines, especially 
where very hard rock had to be operated' upon, was 
speedily established in Sweden, Germany, and some 
other countries ; but its extensive manufactur e and em¬ 
ployment was very soon followed by numerous fearful 
accidents, which appear mainly ascribable to the phy¬ 
sical peculiarities of the substance. Its liquid nature, 
though valuable in special instances of its employment, 
constituted a serious obstacle to its safe transport, 
storage, and use; its liability to leak from receptacles 
in which it was stored and the great susceptibility to 
explosion, by friction or blow, of portions which es¬ 
caped confinement, were unquestionably fruitful sources 
of accident. The precaution of storing and transport¬ 
ing nitro-glycerine in the form of a non-explosive solu¬ 
tion in wood-spirit did not prove to bo a trustworthy 
safeguard against accident, as the spirit was liable to 
evaporate or become weaker, and thus allow the nitro¬ 
glycerine to separate from it to a sufficient extent to 
re-establish danger. 
A very simple expedient, which Nobel devised in 1S67, 
soon enabled him to provide the miner with nitro-gly- 
