THE 



AMERICAN 



JOURNAL OF SCIENCE AND ARTS. 



[SECOND SERIES.] 



ART. XII. — On the Measurement of the Pressure of Fired Gun- 

 powder in its Practical Applications ; by William E. Wood- 

 bridge, M.D* 



Early in the history of scientific gunnery the pressure of the 

 gases generated by the combustion of gunpowder was made the 

 subject of inquiry and experiment. Gen. Antoni of the Sar- 

 dinian army, writing about the year 1785, narrated experiments 

 on this subject, and stated that fine war-powder fired in a cylin- 

 dric cavity half an inch in diameter and height, with no other 

 opening for escape than the vent through which it was fired, 

 exerted a pressure of from 1900 to 1400 atmospheres. This he 

 deduced from the weight required to close the orifice of the 

 eprouvette against the force of the explosion. 



Count Eumford, in his experiments made in 1793, on the same 

 subject, used an apparatus in which the escape of gas by the vent 

 was prevented ; the powder being fired by heating the closed 

 end of a tube filled with it and communicating with the interior 

 of his eprouvette. The pressure of the gases was measured by 

 the means before referred to. The capacity of his eprouvette 

 was about 25'5 grains of powder. With this apparatus he ex^ 

 perimented on the force exerted by different charges from one 

 grain upward, and from the results constructed an empirical 

 formula, expressing very nearly the relation of the indicated 

 expansive force of the gases to their density. The maximum 



SECOND SERIES, VOL. XXII, NO. 65.— SEPT., 1856. 



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