POWDEB.] 



SHOOTING, 



[pOWDEB. 



sation of the air, immediately in advance of it, 

 may be very great before the resistance trans- 

 mitted to the muzzle is at all considerable ; in 

 which case the mutual repulsion of the particles 

 of the air so compressed will offer an absolute 

 barrier to the advance of the wadding. If this 

 explanation be correct, additional recoil, when 

 a gun is loaded with small shot or sand, may 

 arise, in some measure, from the condensation 

 of the air contained between their particles, 

 but chiefly from the velocity communicated 

 by the explosion to those particles of the sub- 

 stances in immediate contact with the powder, 

 being greater than that with which a wave can 

 be transmitted through them. It otherwise 

 affords a reason for the success usually attend- 

 ing the blasting of rocks. That the destruction 

 of the gun-barrel does not arise from the 

 property possessed by fluids, and in some 

 measure also by sand and small shot, of press- 

 ing equally in all directions, and thus exciting 

 a force against a large portion of the interior 

 surface, seems to be proved by a circumstance 

 mentioned by La Vaillant and other travellers 

 — that for the purpose of takiug birds without 

 injuring their plumage, they filled the barrel 

 of their fowling-pieces with water, instead of 

 loading them with a charge of shot. The same 

 reasoning explains a curious phenomenon which 

 occurs in firing a still more powerfully explosive 

 substance. If we put a small quantity of ful- 

 minating silver upon the face of an anvil, and 

 strike it slightly with a hammer, it explodes ; 

 but, instead of breaking either the hammer or 

 the anvil, it is found that that part of the face 

 of each in contact with the fulminating silver 

 is damaged. In this case, the velocity com- 

 municated by the elastic matter disengaged 

 may be greater than the velocity of a wave 

 traversing steel; so that the particles at the 

 surface are driven, by the explosion, so near to 

 those next adjacent, that when the compelled 

 force is removed, the repulsion of the particles 

 within the mass, drives back those nearer the 

 surface with such force, that they pass beyond 

 the limits of attraction, and are separated 

 in the shape of powder. The success of the 

 experiment of firing a tallow candle through a 

 deal board would bo explained in the same 

 manner, by supposing the velocity of a wave 

 propagated through deal, to be greater than 

 that of a wave passing through tallow. 

 504i 



Experiments to try the strength of their 

 powder have often been made by sportsmen ; 

 but the excellence of powder is generally de- 

 termined by the quality of the nitre of which 

 it is partly composed. This ingredient, as 

 already observed, having a strong tendency 

 to absorb moisture, requires that it should be 

 kept in its purest state for the manufacture 

 of powder. When mixed with salt its quality 

 is greatly deteriorated ; and, in all good pow- 

 der, it is well known that its expansive force 

 is in proportion to the velocity with which the 

 communication flies through the whole mass. 

 It is this principle which renders it so well 

 adapted to sporting purposes. No bird or 

 quadruped can fly or run with such rapidity as 

 to get beyond the quickness of its action, pro- 

 vided either be within range. It is this quick- 

 ness of ignition which gives, in the field, such 

 an advantage to powder over every other sub- 

 stance. 



The method of testing the quality of pow- 

 der, instituted and pursued by the Board of 

 Ordnance, is as follows : — The triers first take 

 out of the several barrels of gunpowder a 

 measure-full, of about the size of a thimble, 

 which is spread upon a sheet of fine writing- 

 paper, and then fired. If the inflammation be 

 very rapid, the smoke rises perpendicularly; and 

 if the paper be neither burned nor spotted, it 

 is then judged to be good powder. Then two 

 drachms of the same powder are exactly 

 weighed and put into an epreuvette, which, if 

 it raise a weight of twenty-four pounds to the 

 height of three inches and a-half, is received 

 into the government magazine as proved. 



This powder-trier just mentioned, called an 

 epreuvette, may be seen in many gunsmiths* 

 shops. It does not, however, test the power 

 of the explosive substance with very great 

 nicety, but it is, nevertheless, a useful instru- 

 ment ; and it furnishes the sportsman with a 

 general idea on the subject, which enables him, 

 in many cases, to detect a bad and impure com- 

 modity. 



Percussion gunpowders have effected great 

 changes in sporting art, and the science of 

 projectiles generally. Detonating substances 

 are but of modern date. 



The discovery oi fulminating mercury, which 

 forms the percussion powder now in use, is 

 attributed to Mr. Howard ; the full particulars 



