690 



GUNPOWDER GUNPOWDER PLOT. 



marble cylinders, turn round a fixed vortical wooden 

 pillar, and crush to pieces the mixture, which lies 

 upon a round smooth surface of the same material. 

 Other mills effect this bruising operation by several 

 large iron runners, revolving upon a metallic jilate, 

 similar to a painter's grinding stone, or by a rapid 

 revolution of the mixture in casks containing metallic 

 halls. After the mixture, in some one of these ways, 

 has been acted on in the mills for the space of six or 

 eight hours, and when the ingredients are united, and 

 form one homogeneous mass, it is pressed, while yet 

 wet, by means of cylindric rollers of wood, through 

 a sieve of perforated parchment, by which the powder 

 is formed into grains. In other mills, this process of 

 forming it into grains takes place after the powder 

 has been pressed between two boards into a solid 

 cake, and then submitted twice to the operation of a 

 grooved roller. The powder, after it has been 

 grained, is spread upon boards in the drying-houses, 

 and exposed to the strong heat of an oven for two 

 lays. In order to prevent its taking fire, the oven 

 is well lined with clay and copper. Of late years, 

 this process of drying has been sometimes effected by 

 means of steam. Finally, the powder is sorted by 

 being passed through several sieves. In the first or 

 coarsest, remains what is entirely useless ; through 

 the second passes the second sized, or cannon powder; 

 and through the third and last passes the finest, or 

 musket powder. The powder, thus prepared, is 

 packed in oaken casks. In order to provide against 

 accidents, the English use copper casks or vessels, 

 with the tops screwed on. Good gunpowder must be 

 of a slate colour, uniform, round, and pure grain, and 

 also have a uniform colour on being broken up ; nor 

 should it leave behind it, either on the hand or on 



Eaper, any black spots. When set on fire, it should 

 urn at once, without crackling or leaving upon 

 paper any appearances of its combustion. When 

 applied to the tongue, the taste should be extremely 

 cooling. In order to prove its strength, let any 

 person apply an accurately fitting ball to a small 

 mortar, and the distance to which the ball is thrown 

 will prove the strength of the powder. The French 

 government eprouvette is a mortar seven French 

 inches in diameter, and three ounces of powder must 

 throw a copper globe, of sixty pounds weight, 300 

 feet ; otherwise the powder is not admissible. An 

 eprouvette is sometimes used which is inaccurate ; the 

 powder throws back the cover of a small mortar, and 

 with it a wheel, which catches in a steel spring ; the 

 strength is determined by the tooth, at which the 

 wheel remains fixed. This method is defective, 

 because the spring is weakened by use. Another 

 method is, to suspend a small cannon as a pendulum, 

 and to judge of the strength of the powder by the 

 force of the recoil, which will describe a greater or 

 less arc of a circle. 



In the preservation of powder, fire and water must 

 both be carefully guarded against. Powder destined 

 for military purposes, should be deposited in an airy 

 building, removed at least 1000 paces from any 

 habitation, provided with lightning rods, and sur- 

 rounded with walls, ditches, and palisadoes ; there 

 should be a guard constantly set, to prevent the 

 introduction of fire, and to hinder all persons from 

 entering, who have things about them that will 

 produce fire. These buildings should contain open- 

 ings for the free passage of the air ; the casks should 

 aland upon a platform of wood, at a distance from 

 the wall, and the powder itself should be sunned and 

 dried every one or two years. If the powder is to 

 be kept in damp places, as, for example, in the 

 casemates (arched passages under ground) of for- 

 tresses, the walls should be internally covered with 

 lead, and a vessel filled with unslacked lime placed 



in the middle of the apartment, so that the moisture 

 of the atmosphere may be attracted by the lime, hi 

 the transportation of gunpowder, dust, which is liable 

 to penetrate the cracks and joints of the rasks, 

 sjiould be carefully guarded against, as the friction 

 may produce explosion. It is also necessary for its 

 good preservation, that the carriages and vessels in 

 which it is transported should be water-tight. We 

 may effectually preserve it from moisture, by dipping 

 the cask and the sackcloth covering into melted 

 pitch. Vessels prepared in this way, and containing 

 powder, may be immersed in the water for weeks, 

 without having their contents in the least injured. 



The effects of this substance, when set on fire, are 

 truly wonderful. When powder is heaped up in the 

 open air, and then inflamed, it detonates without 

 report or effect. A small quantity of powder left 

 free in a room, and fired, merely blows out the 

 windows ; but the same quantity, when confined in a 

 bomb within the same chamber, and inflamed, tears 

 in pieces and sets on fire the whole house. Count 

 Rumford loaded a mortar with one twentieth of an 

 ounce of powder, and placed upon it a 24 pound 

 cannon, weighing 8081 pounds ; he then closed up 

 every opening as completely as possible, and fired 

 the charge, which burst the mortar with a tremen- 

 dous explosion, and raised up this immense weight. 

 Mr Robins, engineer general to the East India 

 company, made experiments in order to ascertain the 

 elastic force of the vapour produced by inflaming 

 gunpowder, and concluded that the weight of the 

 vapour was about three- tenths of the weight of the 

 powder from which it was produced, and 244 times 

 its bulk when allowed to expand to an elasticity equal 

 to that of the atmosphere. To this expansive force 

 of the gas evolved from the powder, must be added 

 the effect of the heat, raised during the combustion, 

 which will at least increase the elasticity four times, 

 making the elastic force 1000 atmospheres, in round 

 numbers, which, reckoning one atmosphere as equal 

 to a pressure of 14lbs. to the square inch, will give, 

 for the force of the gas of confined gunpowder, a 

 pressure of about six and a half tons to each square 

 inch. The effect of powder is much impaired by the 

 humidity of the air, but not by its density. Gun- 

 powder may be heated to a point just below that of 

 faint red, when it will be decomposed by the sulphur 

 burning off, and it would appear that explosion does 

 not take place under a temperature of 600 Fahren- 

 heit. Whence such and similar effects arise, no 

 chemist has as yet been able to explain ; and the 

 greater part of the explanations hitherto made are 

 nothing but descriptions of facts. The best expla- 

 nation is, that the azote and oxygen gases of the salt- 

 petre, and the carbonic acid gas from the charcoal, 

 which had hitherto been in a solid state, are set free, 

 and the expansive power of all these gases requires 

 much more room than they previously occupied. They 

 now endeavour to overcome the obstructions to their 

 expansion, and this tendency is very much increased 

 by the intense heat generated by the gases. Tho 

 confined steam operates in the same way, although 

 this is not the only cause of the phenomenon, as 

 Rumford supposes. 



GUNPOWDER PLOT ; a conspiracy formed in 

 the second year of the reign of James I. (1604), for 

 the purpose of destroying the king and parliament 

 at a blow. The Roman Catholics having been dis- 

 appointed in their expectations of indulgence from 

 James, Catesby and Percy, two Catholic gentlemen 

 of ancient family, with a few others of their persua- 

 sion, determined to run a mine below the hall in 

 which parliament met, and, on the first day of the 

 session, when the king and the royal family would be 

 present, involve all the enemies of the Catholic rcli- 



