produced. At the same time the new process ensures a uniform density
throughout the block, and permits of any required density, from 1.4
downwards, being attained; it is also possible exactly to regulate the
percentage of moisture, and to ensure its uniform distribution. The
maximum percentage of moisture depends, of course, upon the density. By
the methods of compression gun-cotton blocks hitherto employed, blocks of
a greater thickness than 2 inches, or of a greater weight than 9 lbs.,
could not be made, but with the new process blocks of any shape, size,
thickness, or weight that is likely to be required can be made readily and
safely. The advantages which are claimed for the process may be enumerated
as follows:--(1.) There is no space wasted, as in the case with built-up
charges, through slightly imperfect contact between the individual blocks,
and thus either a heavier charge--i.e., about 15 per cent. more gun-
cotton--can be got into the same space, or less space will be occupied by
a charge of a given weight. (2.) The metallic cases for solid charges may
be much lighter than for those built-up, since with the former their
function is merely to prevent the loss of moisture from wet gun-cotton, or
to prevent the absorption of moisture by dry gun-cotton. They can thus be
made lighter, as the solid charge inside will prevent deformation during
transport. With built-up charges the case must be strong enough to prevent
damage, either to itself or to the charge it contains. For many uses a
metal case, however light, may be discarded, and one of a thin waterproof
material substituted. (3.) The uniform density of charges made by this
process is very favourable to the complete and effective detonation of the
entire mass, and to the presence of the uniform amount of moisture in
every part of the charge. (4.) Any required density, from the maximum
downwards, may be obtained with ease, and any required amount of moisture
left in the charge. These points are of great importance in cases where,
like torpedo charges, it is essential to have the centre of gravity of the
charge in a predetermined position both vertically and longitudinally, and