220 Mr. J. Ennis on the Origin of the Power 



up in its chemical force, and in the repulsion of its three gases, 

 oxygen, nitrogen, and carbonic acid. These gases were 

 floating about in the air until the chemical force laid hold on 

 thorn, and pressed them down into the small solid materials of 

 the powder. The nitrogen and oxygen were quietly combined 

 as nitric acid, and then united with the potassa of the earth, 

 forming nitrate of potassa, or saltpetre. The gaseous carbonic 

 acid was absorbed through the stomata of plants, then dissolved, 

 and its carbon hardened into wood, or rather the charcoal of 

 the wood. This saltpetre and charcoal, with a very little sul- 

 phur, are the only components of gunpowder. We know how 

 the least spark liberates these imprisoned gases ; and how ter- 

 ribly their native repulsive power shows itself, not only with 

 thundering sound, but with the power of thunder, and with 

 the heat of lightning. 



The materials of gunpowder show this power, not only in 

 the thunder-like explosion and the lightning-like heat, but 

 also in vast stores of chemical force. One of the elements of 

 saltpetre, composed of oxygen and nitrogen, is the violent 

 aqua fortis, or nitric acid. Two other gases, hydrogen and 

 chlorine, are combined and condensed by chemical force into 

 a very different material called hydrochloric acid. These two 

 acids when combined show their power by dissolving gold as 

 a lump of sugar is dissolved in a cup of tea. Hydrogen and 

 nitrogen also are combined and condensed by the chemical 

 force into the violent ammoniacal gas. This ammonia com- 

 bines with the nitric acid, and the two are hardened by the 

 chemical force into a solid, the nitrate of ammonia. All these 

 are striking instances of the way the repulsive force may be 

 overcome and converted into the chemical force, this chemical 

 force being lodged in vast abundance in small amounts of the 

 resulting solids and liquids. How inert and comparatively 

 feeble are the chemical properties of the four gases which 

 form aqua regia (oxygen, hydrogen, nitrogen, and chlorine) ! 

 But the force residing in them in the form of repulsion is 

 great beyond expression, beyond measurement. Think of the 

 wonderful mechanical force lately found necessary to reduce 

 them to a liquid condition — still retaining their repulsion and 

 ever ready to burst out into their native gaseous state. As they 

 can be so easily reduced to the solid condition by the chemical 

 force, this is an impressive illustration of the great power of the 

 chemical force in overcoming and appropriating to itself the 

 repulsive force. The great idea here conveyed is that the 

 repulsive force of these gases cannot be annihilated. It com- 

 pletely disappears as repulsion when these gases are solidified 

 or liquified; but it is converted into the chemical force. 



