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to effect its condensation under a force of more than 60,000lbs. 
per square inch. By carrying the pressure in this way far 
beyond the ordinary limits, it was expected that the precise 
influence of compression on the properties of the powder 
would be more clearly and accurately exhibited. 
The samples of powder were placed in a wrought iron box, 
and compressed by a lever acting upon them by a solid piston 
with a force varying from 38,000lbs. to 67,OOOlbs. per square 
inch in the different specimens. When taken from the apparatus, 
the powder was found to have been consolidated into cylinders 
of 1;| inches in diameter with smooth polished surfaces, every 
trace of its granular character having disappeared. 
From the Report of Mr. Abel, the Chemist of the War 
Department, we learn that the specific gravity of the speci- 
mens was increased by the pressure, but not to so great an 
extent as might have been expected. 
The specimens having been granulated were then burned, 
and it was found, on comparing the results with those of 
similar experiments on ordinary press-cake, that the amount 
of residue left by the compressed powders, after ignition, was 
greater in proportion as the pressure was increased. This 
increase of residue is probably to be attributed to the more 
gradual combustion and the diminished intensity of heat 
generated by compressed powder. 
Experiments were then instituted to determine the amount 
of charcoal left uneonsumed in the residue. They showed 
conclusively that the condensation of the powder had caused 
a more perfect chemical action in combustion, as the per- 
centage of carbon was considerably diminished in the 
compressed powders. Nitric acid was very carefully searched 
for in the residues of the compressed powders, but none could 
be detected, although in ordinary gunpowder a portion of the 
acid of the saltpetre always escapes decomposition. 
An important objection to the application of increased 
pressure in the manufacture of gunpowder, notwithstanding 
