Comhitftion of Guiipowdir in a Clojed Vejjftl. 4c« 



VI. 



An Account offome £xpcriments to detcrmint the Force of Fired Gunpowder. By BENJAMIN 

 Qount of Rum FORD, F. R. S. M. R. I. A. * 



A. 



wFTER obferving that no' human. invention, except perhaps the art of printing, appears 

 to have produced fuch important changes in civil fociety as the invention of gunpowder ; 

 that notvvithflandlng the extenfive ufes to whicli this wonderful agent is applied, it feems 

 not hitherto to have been examined with the attent ion it merits, and that probably this want 

 of inveftigation may have arifen from the danger attending the experiments ; our author 

 proceeds to relate his own experiments and obfervations. 



Several eminent philofophers and mathematicians have, from time to time, diredled their 

 attention to this fubje£l. The modern improvements in chemiftry have greatly elucidated 

 the caufe and circumftances attending the explofion of gunpowder. But the great defide- 

 ratum, namely, the real meafure of the initial expanfive force of this agent, has not yet been 

 determined. Robins, from his experiments, concluded that the elaftic force of the fluid 

 generated in the combuftion of gunpowder, is one thoufand times greater than the mean 

 preflure of the atmofphere ; but the celebrated Daniel Bernouilli determines its force to be 

 notlefs than ten thoufand times the faine mean preflure. Count Rumford, being ftruck with 

 the great difference in thefe refults, has occafionally, for many years, endeavoured to afcertain 

 the truth by experiment. In a paper printed in the year 1 781, in the Tranfadions, he gave 

 an account of an experiment, No. 92, by which it appeared that, calculating even upon Mr. 

 Robins's own principle, the force of gunpowder mufl. be at leaft 1308 times greater thant 

 the mean preflure of the atmofphere ; and from that, and many other experiments, he be- 

 came convinced that it was neceffary to abandon the methods of that philofopher, and make 

 others with a very different apparatus. 



His firft attempts were to fire gunpowder in a confined fpnce, thinking that when he 

 had accompliflied this he fliould find means of meafuring its elaRic force without difficulty. 

 A very ftrong fliort gun-barrel was prepared, and attempts made to fire gunpowder in the 

 fame, by means of a fmall vent, provided in one inftance with a valve, and in another expe- 

 riment lined with gold to prevent corrofion. Thefe attempts were unfuccefsful ; the force 

 of the explofion proving fufficiently great to enlarge the hole, and fo rapid as not to allow 

 time for clofure of the valve. It became neceffary, therefore, to endeavour to fire the gun- 

 powder by means of heat conveyed through the mafsof the metal itfclf. This was fuccefs- 

 fuUy performed in a barrel of the befl forged iron, 3,45 inches long, the diameter of its bore 

 ^'■jthsof an inch, and its ends clofed up by two fcrews, each one inch in length, which were 

 iirraly and Itrunov^ably fixed in their places by folder. The vacuity between ihem in the 

 barrel was confequently 1,15 inch in length, and conflituted the chamber of the piece, 

 whofe capacity was nearly -,\thsof a cubic inch. The thicknefs of the metal was equal to 

 the bore of the piece. An hole 0,37 of an inch in diameter was bored through both fides 

 of the barrel, through the centre of the chamber, and at right angles to its axis. Two tubc» 

 of iron, 0,37 of an inch in diameter, the diameter of whofe bore was rjth of ^n inch, were 

 iiimly fixed in thefe holes with folder, iu fuch a manner, that, while their internal openinos 



.^bric'god from ;!if ?liilofoii'>ica! Tranfaftions for 1797, p. ;s«. 



3 N 2 were 



