F. A. P. Barnard on the Explosive Force of Gunpowder, 241 
Art. XXIV.—On the Explosive Force of Gunpowder ; by Prof. 
F, A. P. BARNARD. 
AUTHORITIES very widely differ as to the degree of strain to 
which heavy guns are subjected in experimental or in service 
firing ; and still more widely in their estimate of the expansive 
force which gunpowder would be capable of exerting, could it 
be exploded in a space incapable of enlargement, which it ex- 
actly fills. 'The magnitude of the differences may be illustrated 
by the following examples. 
n the work published in 1742 by Benjamin Robins, entitled 
“New Principles of Gunnery,” the absolute expansive force of 
gunpowder exploded within its own bulk, is set down at one 
thousand atmospheres. This estimate was founded on certain 
experiments which may briefly be described as follows: First, 
by actually collecting the gases generated by the combustion of 
a given weight of powder, Mr. Robins inferred that these gases, 
reduced to the actual temperature previous to explosion, exceed, 
under the ordinary atmospheric pressure, the bulk of the pow- 
der by which they are produced in the ratio of 244 tol. In 
order to ascertain the effect upon elasticity produced by the heat 
of combustion, he drew out a portion of a musket barrel into a 
conical form, leaving an orifice at that end of only one-eighth 
of an inch. The other end being closed, he subjected the appa- 
ratus to the highest heat of a furnace, and then immersed the 
conical end (which he first stopped with an iron plug 
After the tube had sufficiently cooled, he removed the P 
allowed the water to enter. The amount of the fluid found in 
computed the maximum ible elasticity of the gases generated 
das at 9994 atmospheres; or, in round 
At a later period this subject was ghana by Gay Lussac. 
rding to bis determination, the bulk o 
tion at 1000° C.; and computes the resulting elastic pressure at 
more than 2100 atmospheres. 
Am. Jour. Sc1—Szconp Series, Vou. XXXVI, No. 107.—Sxpr., 1863. 
31 
