276 
MODERN GUNPOWDER AND CORDITE. 
There are only two of the methods referred to in the table which our 
limited time will allow us to mention in detail. The first is change of 
form and moulding. It needs no explanation to demonstrate that a 
charge consisting of regularly shaped moulded powder of uniform size 
will give (other things being equal) more uniform results than could 
be obtained by an equal weight of irregular grains or lumps. But the 
modern shape, the perforated moulded prism, possesses further advan¬ 
tages over the other forms, which are worthy of consideration. If we 
take any of the old grain powders, or a mass or lump like P 2 , we know 
that it burns from surface to centre. This being so, the surface of 
combustion decreases as the shot travels in the bore, or as the space 
behind the shot increases. That is to say, we find a reducing evolution 
of gas when you really most require an increasing one; and hence the 
speed or velocity of the projectile is not developed in the most satis¬ 
factory manner. On the other hand, if we now look at the perforated 
prism, we find that as the outside surface is diminished by combustion 
so the inside surface of the perforation is increased; thus we see a ten¬ 
dency to keep up a constant supply of speed producing gasses; and 
further, when the combustion reaches a certain point it is more than 
probable that the prisms break up across the lines of least resistance 
(they are marked in fig. a 3 a } b } h, and so on), thereby producing 
Partly burned, and broken up across Unburned, 
the lines of least resistance. 
twelve new surfaces f\ / 2 , / 3 , &c., for combustion ; fully developing 
the progressive character of the powder, and helping the projectile 
along as its speed is accelerated. 
The second detail of the diagram to be brought to notice is “ Blend¬ 
ing,” upon which chiefly the uniformity of character of the powder 
depends, and few who have not practically studied the subject, can 
realise how difficult it is to obtain this uniformity. For example, a 
day’s production represents about a unit or lot of 100 barrels, equal to 
10,000 lbs. of gunpowder. This large quantity must be absolutely 
uniform in itself. That is to say, every charge from it, fired from the 
same gun, under similar circumstances, should give identical results as 
to speed and pressure. This batch of powder is, however, made in 
many machines, on the out-turn of which the weather and temperature 
exert considerable influence, and besides this, the machines are tended 
and worked by different men, each of whom has what may be termed 
