200 ELEMENTARY PRINCIPLES OF GUNNERY. 



tioned that in theory every particle of the original substances 

 of which it is composed should be converted into gas, leaving 

 no residuum to foul the barrel. In practice this is never the 

 case, for though a powder may be made so correctly as to 

 burn away almost entirely on a piece of white paper, yet in 

 a tube it will always leave a stain over and above the sul- 

 phuret of potassium, which is a necessary product, and this 

 increases if not wiped away with each succeeding discharge. 

 The reason of this is, that there is no air admitted to supply 

 extra oxygen for the sulphur to combine with, and this 

 material, therefore, robs the nitre of a small portion of that 

 element which is wanted to effect a perfect union with the 

 carbon in order to form the carbonic oxide and acid which 

 result. Gunpowder may be made entirely of nitre and char- 

 coal, and for large charges it answers perfectly well, but for 

 sporting purposes the addition of sulphur has many advan- 

 tages, preserving the other two materials from the effects of 

 damp, and also maintaining the granulation which is so im- 

 portant in effecting perfect combustion. In this country 

 the proportions which are thought to answer best in prac- 

 tice are 



Nitre 77|lbs. 



Charcoal 16 



Sulphur 10i,, 



This will make 1041bs. of powder, leaving the 41bs. for 

 loss by waste in the various operations of mixing, pressing, 

 granulating, &c. These three substances must first be 

 ground into a very fine powder, and mixed together most 

 intimately, so that the atoms are mechanically prepared for 

 instantaneous combination as soon as they are heated to 

 the temperature which admits of it. But if left in this 

 state of fine powder, though the combination is very rapid 

 in the parts first heated, yet the flame cannot permeate the 

 mass, and it burns imperfectly as a whole. To avoid this 

 difficulty the powder is first wetted, then pressed and dried, 

 and afterwards made up into grains of various sizes and 

 shapes, according to the use for which it is designed. This 



