Experiments ^tpon Gtinpowder. 35 



all the better kind of fowling-pieces the vent is lined 

 or bouched with gold, and they are found to stand fire 

 for any length of time without receiving the least injury. 

 But everybody knows that gold will run with a less heat 

 than is required to melt iron ; but gold is not liable to 

 be corroded by anything that can be produced in the 

 combustion of gunpowder; but this is not the case with 

 iron, and that I take to be the only reason why a vent 

 that is lined with gold is so much more durable than 

 one that is made in iron. But it seems that iron is 

 more durable than brass ; and perhaps steel or some 

 other cheap metal may be found that will supply the 

 place of gold, and by that means the great expence 

 that attends bouching pieces with that precious metal 

 may be spared, and this improvement may be intro- 

 duced into common use. 



This leads us to a very easy and effectual remedy for 

 that defect so long complained of in all kinds of brass 

 ordnance, the running of the vent; for if these pieces 

 were bouched with iron, there is no doubt but they 

 would stand fire as well as iron guns ; and if steel, or 

 any other metal, either simple or compounded, should, 

 upn trial, be found to answer for that purpose better 

 than iron, it might be used instead of it ; and even if 

 . gold were made use of for lining the vent, I imagine it 

 might be done in such a manner as that the expence 

 would not be very considerable, at the same time that 

 the thickness of the gold should be sufficient to with- 

 stand the force of the flame for a very great length of 

 time. 



But to return to the heat acquired by guns in firing. 

 It being pretty evident that it is not all communicated 

 by the flame, there is but one other cause to which it 



