Phenomena of the Camhiijlian of Gunpvwder, cj r 



VII. 



An Account of fame Experimstits to deterin'me the Force of fired Gitiipowier. By BENJAMIN 

 Count of RvMFORD, F.R.S. M.R.I./!. 



A. 



[Concluded from page 468.] 



^FTER tabulating the experiments, of which an abftrafl was given in our lad number, 

 the Count proceeds to afcertain the law, according to which the elafticities-increafe in pro- 

 portion to the quantities of powder ufed for the charge. For the fake of brevity, as well as 

 becaufe the fubjefl appears to require ftill further invcfligation than he has bellowed upon 

 it, I fliall refer the reader to the paper itfelf, inftead of attempting to give an abridged ac- 

 count of this part, and ftiajl proceed to relate the other experimental refults contained in his 

 paper. 



After having fhewn the extreme force of fired gunpowder, he adverts to an objedion 

 which may be made againft his deduftions. How does it happen that fire-arms and ar- 

 tillery of all kinds, which certainly are not calculated to withlland fo enormous a force, are 

 not always burft when they are ufed ? Inftead of anfwering this queftioii, by aficing how it 

 happened that the extremely ftrong barrel ufed in his experiment could be burft by the force 

 of gunpowder, if tliis force be not in fad): much greater than it has ever been fuppofed to be, 

 he proceeds to fl^ew that the combuftion of gunpowder, inftead of being inftantaneous, as 

 Mr. Robins's theory fuppofes, is much lefs rapid than has hitherto been apprehended ; an 

 obfervation, which, if eftablifhed, is certainly fufficient to anfwer the objeiftion. 



He remarks, that it is a well known fa£t, that on the difcharge of fire-arms of all kinds, 

 cannon and mortars as well as mufkets, there is always a confiderable quantity of uncon- 

 fumed grains of gunpowder blown out of them ; and what is very remarkable, as it leads di- 

 reftly to a difcovery of the caufe of this effedl, thefe unconfunied grains are not merely blown 

 out of the muzzles of fire-arms, but come out alfo by their vents or touch-holes, where the 

 fire enters to inflame the charge, as many perfons who have had the misfortune to ftand 

 with their faces near the touch-hole of a mulket, when it has been difchargedj have found 

 to their coft. 



It appears extremely improbable to our author, if not abfolutely impoflible, that a grain of 

 gunpowder aiflualiy in the chamber of the piece, and completely furrounded by flame, 

 fiiould, by the aiftion of that very flame, be blown out of it without being at the fame time 

 fet on fire. And, if this be true, he confiders it as a moft decifive proof not only that the 

 combuftion of gunpowder is lefs rapid than it has generally been thought to be, but that a 

 grain of gunpowder adually on fire, and burning with tiie utmoft violence over the whole of 

 its furfacc, may be projedcd with fuch a velocity into a cold atmofphcrc, as to extinguiflithe 

 fire, and fufl^er the remains of the grain to fall to the ground unchanged, and as inflammable 

 as before. 



This extraordinary fa£t was afccrtained beyond all poffibility of doubt by the Count's ex- 

 periments. Having procured from a powder-mill in the neighbourhood of the city of Mu- 

 nich a quantity of gunpowder, all of the fame mafs, but formed into grains of very different 

 fjzesjfomc as fmall as the grains of tlic fincfl: Battle powder, he placed a number of vertical 



3 U 2 fcreens 



