GUNPOWDER. 457 



From the large quantity of oxygen which nitre contains, and 

 the facility with which it imparts that element to combustibles 

 at a red heat, it is much employed in making gunpowder and 

 other deflagrating mixtures. An intimate mixture of nitre in 

 fine powder with l-3rd of its weight of wood charcoal, when 

 touched by a body in ignition, burns with great brilliancy, but 

 without explosion. A mixture of 3 parts of nitre, 2 of dry car- 

 bonate of potash, and 1 of sulphur, forms pulvis fulminans, 

 which heated gently till it enters into fusion, inflames suddenly, 

 and explodes with a deafening report. The violence of the ex- 

 plosion is caused by the reaction between the sulphur and nitre 

 being instantaneous, from their fusion and perfect intermixture, 

 and the consequent sudden formation of much nitrogen gas from 

 the decomposition of nitric acid. Gunpowder contains both 

 sulphur and charcoal, of which the former serves the purpose of 

 accelerating the process of deflagration and supplying heat, 

 while the latter supplies much of the gas, to the formation of 

 which the available force of the explosion is due. Gunpowder 

 yields about 300 times its volume of gas, measured when cold ; 

 but its explosive force is greater than this indicates, from the 

 high temperature of the gas, and not less than 1000 atmos- 

 pheres. The ordinary proportions of gunpowder approach very 

 nearly 1 eq. of nitre, 1 of sulphur, and 3 of carbon, as will be 

 seen by the following comparison : 



COMPOSITION OF GUNPOWDER. 



Theoretical Mixture. English. Prussian. 



Sulphur . . 11.9 . .12.5 . . 11.5 

 Charcoal . . 13.5 . . 12.5 . . 13.5 

 Nitre . . . /4.6 . 75. . 75. 



100. 100. 100. 



By the combustion of the mixture, carbonic acid and nitrogen 

 gases are formed, with a solid residue of protosulphuret of 

 potassium. Thus : 



DEFLAGRATION OF GUNPOWDER. 



Before Decomposition. After Decomposition. 



3 Carbon. 3 Carbon. -_^3 Carbonic acid. 



i\r* f 6 Oxygen. .. "** 



Njtrate of I Nit ^ Nitrogen. 



Potash. \ potash- 

 Sulphur. Sulphur. ^^^^-^Sulphuret of potassium.. 



