It will be observed that the practical results vary largely from the
theoretical values, but they seem to indicate that gun-cotton and No.
1 dynamite are very nearly equal to each other, and that in the
nitro-glycerine compounds, except where gun-cotton is added, the force
appears to be nearly in proportion to the nitro-glycerine contained.
From the foregoing it seems fair to estimate roughly the values of
bursting charges of shells as follows:

Powder 1
Gun-cotton and dynamite 6 to 10
Nitro-glycerine 13 to 15
Blasting gelatine 15 to 17

Attention has been turned in Europe for more than thirty years toward
firing high explosives in shells; but it is only within very late
years that results have been reached which are claimed as
satisfactory, and it is exceedingly difficult to obtain reliable
accounts even of these. Dynamite was fired in Sweden in 1867 in small
quantities, and a few years later it was fired in France. But two
difficulties soon presented themselves. If the quantity of
nitro-glycerine in dynamite was small, it could be fired in ordinary
shells, but the effect was no better than with gunpowder. If the
dynamite was stronger in nitro-glycerine, it took but a small quantity
to burst the gun.

As early as 1864, dry gun-cotton was safely fired in shells in small
quantities, but when a sufficient quantity to fill the shell cavity
was used, the gun burst. Some few years ago it was found that if the
gun-cotton was either wet or soaked in paraffin, it could be fired