376 
ME. F. A. ABEL’S CONTEIBTTTIONS TO 
similar to that which would be presented by a perfectly solid mass. Similarly if, 
instead of water only, the strong vessel be completely filled with a mixture of a solid 
substance ( e . g. a fine powder or a fibre reduced to a fine state of division) and water, 
such a mixture should also, at the instant of detonation, behave as a very compact solid 
with reference to the resistance it opposes, at the instant of explosion, to the detonating- 
charge which it encloses. If this be so, then a mixture of even the most finely divided 
gun-cotton fibre with water, if enclosed in a strong receptacle, such as a shell, should 
be in a condition readily susceptible of detonation, because, at the instant of explosion 
of the initiative charge, the particles of gun-cotton offer great resistance to mechanical 
motion. The correctness of this conclusion has been fully established by experiments, 
which have demonstrated that, while it is indispensable to employ gun-cotton in a very 
compact or highly compressed form in order to ensure its detonation under all other 
conditions, it may, if enclosed in strong vessels, such as shells, be employed with equal 
efficiency in a finely divided state, provided the spaces between the particles be com- 
pletely occupied by water, the small detonating charge being immersed in the aqueous 
mixture. The following experimental illustrations of this will serve to compare with 
the shell-experiments given in Table III. 
Spherical cast-iron shells 5% inches (-138 m.) in diameter, and weighing about 16 lb.^ 
were filled with mixtures of finely divided gun-cotton, or pulp, and water. In some 
instances the pulp (containing no more water than remained in it after thorough drain- 
age in a centrifugal machine) was firmly rammed into the shell, a central cavity being 
formed in the mass to receive the “ primer ” of dry gun-cotton ; water was then poured 
in, so as to fill the shell completely, and ample time was allowed for it to soak 
thoroughly into the rammed pulp and expel the air retained by the latter. The 
primer,” which consisted of a cylinder of air-dry gun-cotton weighing 1 ounce (3T2 
grms.), fitted on to the ordinary “ detonator,” and coated with waterproofing material, 
was then inserted into the cavity provided for it (displacing part of the water contained 
in the latter). It was attached to the screw-plug, as in the experiments given in 
Table III., by which the shell was closed as perfectly as possible when the loading 
was completed. In other experiments the pulp was mixed with water to the con- 
sistency of thick paste, and poured into the shell in this state ; in others it was intro- 
duced in a still more dilute condition, the fitting of the shell being completed, in all 
cases, as above described. The shells thus loaded were broken up by the explosion of 
the detonator into a very large number of fragments, of which from 350 to 400 were 
recoverable, a considerable proportion of the shell being, however, almost pulverized 
and buried in the oak casing of the chamber. Many of the larger fragments were also 
driven into the hard wood with great violence, being very difficult to extract ; and the 
effects (both as regards disintegration and violent dispersion) furnished by from 2 to 
4 ounces of gun-cotton used in this way were far greater than those produced with the 
full charge (about 1 lb.) of gunpowder. 
These experiments conclusively demonstrated that gun-cotton in a fine state of divi- 
