d02 PHILOSOPHICAL TRANSACTIONS. [aNNO 1742. 



Separated from 9 dwts. of fresh powder: From Q dwt. of powder collected after 



Nitre 6 dwt. 2 gr. having been discharged with ball : 



Residuum .... 2 7 Nitre 4 dwt. 18 gr. 



Residuum .... 2 15 



Loss O 15 Sand, &c o 11 



Loss 1 14 



Twelve grains of the powder gathered and put into separate boxes, after firing 

 with ball out of the short piece, as before mentioned, being fired in the ex- 

 hausted receiver, sunk the mercurial gage from 29-^ inches to 23-fV- And the 

 same weight of fresh powder being fired in the same manner, sunk the gage to 

 22f ; the diflference being 4-^ of an inch. 



From these experiments the committee are of opinion, that the 1st part of 

 the 1 St question, Whether all the powder of the charge be fired ? is sufficiently 

 determined in the negative. 



As to the 2d part of the 1st question. Whether all the powder that is fired, 

 be fired before the bullet is sensibly moved from its place ? The committee are 

 of opinion, that the bullet is sensibly moved from its place before all the powder 

 that is fired, has taken fire.* 



This, indeed, has net been determined by any direct experiment, but seems 

 a consequence of the determination of the first part of the question, that the 

 whole of the charge is not fired. 



For let it be considered, that from the moment any part of the powder 

 within the barrel takes fire, the flame of the powder already fired is always con- 

 tiguous to some part of the powder as yet unfired ; and consequently some 

 part of this last must be continually taking fire, so long as any unfired powder 

 remains within the barrel ; that is, the firing of the powder cannot be over, till 

 all the unfired powder is driven out of the gun : but before any part, how 

 small soever, of the unfired powder is driven out of the gun, the bullet which 

 lies between the charge and the muzzle, must necessarily have been driven out 

 of the gun. Therefore the firing of the powder is not over, or all the powder 

 that is fired, is not fired till after the bullet is driven out of the gun. And 

 consequently the bullet must be sensibly moved from its place, before all the 

 powder that is fired has taken fire. 



As to the 2d question. Whether the distance to which the bullet is thrown, 

 may not become greater or less, by changing the form of the chamber, though 



• Mr. Robins afterwards determined that the ball is not sensibly moved from its place, when the 

 powder is fired. 



