THE ROYAL ARTILLERY INSTITUTION. 
413 
THE DETERMINATION 
OF 
THE EXPLOSIVE FORCE OF GUNPOWDER. 
A PAPER READ AT THE R.A. INSTITUTION, WOOLWICH, MARCH 15 , 1871 , 
BY * 
CAPTAIN J. P. MORGAN, R.A. 
Colonel W. J. Shythe, R.A., E.R.S., in the Chaik. 
This subject Has been investigated by some very able men, botli theoreti¬ 
cally and practically; but though the facts thus elicited are very valuable, 
the conclusions which have been derived from them are not sufficiently 
harmonious to warrant us in believing that the question has been completely 
solved. 
I. Wiiat has been done. 
1. Theoretically . 
The explosive force of gunpowder may be calculated from the products 
of combustion, on the assumption that certain laws hold good, such as that 
the tension of a gas varies with its density and also with its temperature. 
It must, however, be borne in mind that these laws have been verified only 
within certain limits of pressure and temperature, and, therefore, when we 
come to such very great pressures and temperatures as are met with in the 
explosion of gunpowder, any conclusions founded on them must be received 
with caution until the results have been confirmed by experiment. 
Robins, about the middle of last century, endeavoured to calculate the 
force of gunpowder from the amount of elastic fluid produced. He found 
that the gaseous products would occupy 244 times the bulk of the powder, 
at the temperature and pressure of the atmosphere. If this amount of gas 
were confined in a space of the same size as that occupied by the powder, 
the pressure would be 244 atmospheres, without making any allowance for 
the enormously increased temperature at the moment of combustion. By 
heating a piece of musket barrel to “ the extremest degree of red hot iron ” 
—his assumed temperature of exploded gunpowder—and cooling it in water 
with certain precautions, he found that the heated air it contained contracted 
to one-fourth of its bulk, and concluded that the increase of heat increased 
the elastic force of the gases fourfold. Thus the 244 volumes of gas at the 
temperature referred to would possess an elastic force of 1000 atmospheres, 
or 6*7 tons per square inch. 
