86 On Recent Progress in the History of — 
portant advantages over gunpowder as a blasting and 
destructive agent, but the attempts to introduce it as a 
substitute for gunpowder have already been attended by 
most disastrous results, ascribable in part to some of its 
properties and the evident instability of the commercial 
product, but principally to the thoughtlessness of those in- 
terested in its application, who appear to have been induced 
either by undue confidence in its permanence and com- 
parative safety, or from less excusable motives, to leave 
the masters of ships, or others who had to deal with the 
transport of the material, in ignorance of its dangerous 
character. 
The precise causes of the fearful explosions of nitro-gly- 
ceriné, which occurred at Aspinwall and San Francisco 
will, in all probability, never be ascertained ; but they are 
likely to have been due, at any rate indirectly, to the spon- 
taneous decomposition of the substance, induced or acce- 
lerated by the elevated temperature of the atmosphere in 
those parts of the ships where it was stored. Instances are 
on record in which the violent rupture of closed vessels con- 
taining commercial nitro-glycerine has been occasioned by 
the accumulation of gases generated by its gradual de- 
composition; and it is at anyrate not improbable that a 
similar result, favoured by the warmth of the atmosphere, 
and eventually determined by some accidental agitation of 
the contents of the package of nitro-glycerine, was the 
cause of those lamentable accidents. The great difficulties 
attending the purification of nitro-glycerine, upon a prac- 
tical scale, and the uncertainty, as regards stability, of the 
material, even when purified (leaving out of consideration 
its very poisonous character and its extreme sensitiveness 
to explosion by percussion when in the solid form), appear 
to present insurmountable obsatcles to its safe application 
as a substitute tor gunpowder. 
The conversion of purified lignin or wood fibre into an 
explosive substance of the same nature as gun-cotton, was 
accomplished by chemists soon after Schénbein’s discovery 
of gun-cotton was made known. Finely-divided wood, or 
sawdust, may, by treatment with suitable agents, be, to a 
very considerable extent, purified of substances foreign to 
cellulose; and, if then submitted to careful digestion in a 
mixture of the strongest nitric and sulphuric acids, and 
properly purified, it furnishes a highly explosive material, 
similar to the most explosive gun-cotton, and possessed 
apparently of considerable stability. Captain Schultze, a 
