ADDRESS. ae 
_ that wet compressed gun-cotton, even when containing sufficient water to 
render it quite uninflammable, can be detonated through the agency of a 
- sufficiently powerful charge of fulminate of mercury, or of a small quantity 
of dry gun-cotton imbedded within it, has led to the perfectly safe appli- 
- cation of gun-cotton in shells, provided the fase, through the agency of 
which the initiative detonating agent in the shell comes into operation, 
is secure against any liability to premature ignition when the gun is 
fired. Many successful experiments have been made with shells thus 
charged with wet gun-cotton, which is now recognised as a formidable 
destructive agent applicable in shells with much less risk of casualty than 
attends the use of many other of the violent explosive bodies which it 
has become fashionable, in professional parlance, to designate as ‘high 
explosives.’ 
Many devices and arrangements, more or less ingenious and compli- 
cated, have been schemed, especially in the United States, for applying 
preparations of the very sensitive liquid, nitro-glycerine, such as 
dynamite and blasting-gelatine, as charges for shells. Some of these 
consist in subdividing the charge by more or less elaborate methods ; 
in others the shell is also lined with some soft elastic packing-mate- 
rial, and paddings of similar material are applied in the head and the 
base of the shell-chamber, with the object of reducing the friction and 
concussion to which the explosive is exposed when the projectile is first 
set in motion. Such arrangements obviously diminish the space available 
for the charge in the shell, and the best of them fail to render these ex- 
plosives as safe to employ as wet gun-cotton. In order to avoid exposing 
‘shells loaded with such explosives to the concussion produced when pro- 
pelling them by a powder-charge, compressed air has been applied as the 
propelling agent, and guns of special construction and very large dimen- 
sions, from which shells containing as much as 500 lb. of gun-cotton or 
dynamite are projected through the agency of compressed air, have 
recently been elaborated in the United States, where great expectations 
are entertained of the value, for war-purposes, of these so-called pneumatic 
A highly ingenious device for utilising a class of very powerful 
explosives in shells, without any risk of accident to the gun, was not long 
since brought forward by Mr. Griisen, the well-known armour-plate and 
projectile manufacturer of Magdeburg. It consisted of a thoroughly 
efficient arrangement for applying the fact, first demonstrated by Dr. 
Sprengel, that mixtures of nitric acid of high specific gravity with solid 
or liquid hydrocarbons, or with the nitro-compounds of these, are sus- 
teptible of detonation, with development of very high energy. The two 
agents, of themselves non-explosive—nitric acid and the hydro-carbon, or 
‘its nitro-product—are separately confined in the shell; when it is first set 
_ in motion by the firing of the gun, the fracture of the receptacle containing 
the liquid nitric acid is determined by a very simple device; the two 
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