Mining or blasting powder, which is used for blasting purposes (see BLASTING) , usually has a lower amount of potassium nitrate than mili tary powder, so as to make it slow burning, and the proportions are from potassium nitrate 70 parts, sulphur 18 parts, and charcoal 12 parts, to potassium nitrate 62 parts, sulphur 20 parts, and charcoal 18 parts. The manufacture of blast ing-powder became an important industry in the United States when the construction of canals and railways and mining operations began to be undertaken on a large scale. With the in creased demand for blasting-powder, which origi nally did not differ from ordinary powder, it was found necessary to make a less expensive substance, and accordingly it was found by L. Dupont of Wilmington in 1857 that sodium ni trate or Chilean saltpetre could be substituted for the far more costly potassium nitrate or India saltpetre. As a result of this discovery the manufacture of blasting-powder has attained con siderable importance, and in 1900 there were 37 different establishments in 13 different States engaged in this industry. These factories repre sented $4,900,485 capital, and their output in 1900 was 97,744,237 pounds of blasting-powder, valued at $3,880,910.
Gunpowder, when of good quality, should have a specific gravity between 1.50 and 1.85. It ex plodes at about 313° C. (595° F.), and when ignited on a piece of white paper should burn away rapidly, leaving no residue. If black spots are found they indicate an excess of charcoal, or imperfect mixture, while yellow spots show excess of sulphur. Many studies have been made of the products of combus tion of gunpowder, and the results obtained seem to show that the gases formed are, in proportions varying according to the quality of the powder, as follows: Carbon monoxide, car bon dioxide, nitrogen, hydrogen sulphide, marsh gas, hydrogen, and oxygen. The temperature pro duced by the explosion of gunpowder is estimated at from 2100° to 2200° C. (3812° to 3992° F.), according to the quality of the powder; and the quantity of heat evolved in gram-degree units ranges from 837 down to 518.8.
The production and value of gunpowder, in cluding blasting-powder, produced in the United States is given by decades in the following table from the Twelfth United States Census; accession he was extremely severe in enforcing against them the existing penal laws. Disap
pointed and angered by this policy, a few des perate Catholics banded together to remedy the evil by overthrowing the Government. The origi nator of the scheme was Robert Catesby, a man of good birth, who had plotted against Elizabeth. First he took John Wright and Thomas Winter into his secret. After trying in vain to gain toleration for the Catholics through the media tion of Spain, these three men proceeded to their desperate task. They drew into the plot Guy Fawkes (q.v.), a soldier of fortune, who had made a reputation in war, and whose character was determined and and Thomas Percy, a relative of the Earl of Northumberland. They began to undermine Parliament House from an adjoining tenement which they had hired. One day after they had laboriously pierced the wall, three yards thick, they were alarmed by a noise, which as Fawkes discovered came from a vault under the House of Lords. Finding that this cellar was soon to be vacant, they hired it, and stored in it barrels of gunpowder, which they covered with stones and billets of wood. Their object was not only to conceal the powder, but also to supply an abundance of destructive mis siles. While this work was progressing a brother of Wright, a brother of Winter. and a few other obscure persons were added to the conspirators. But they needed money; and to supply it three others were induced to join the plot—Sir Everard Digby of Gatehurst in Buckinghamshire, a young gentleman of large estates; Francis Tresham, a follower of Essex, like Catesby and Percy, but unlike them a cold, selfish man little suited to a conspiracy of the kind; and Ambrose Rookwood, also a wealthy gentleman residing in the coun BIBLIOGRAPHY. Consult the article on "GunBibliography. Consult the article on "Gun- powder" in lire, Dictionary of Arts, Manufac tures, and Mines (London, 1878) Spon, Ency clopcmlia of the Industrial Arts, Manufactures, and Commercial Products (London, 1879-82) ; Thorne, Dictionary of Applied Chemistry (Lon don, 1890-93) ; and especially the Manufacture of Explosives: A theoretical and practical treatise on the history, the physical and chemical prop erties, and the manufacture of explosives, icith a full bibliography, in two volumes, by Oscar Outt Mann (New York, 1895). See ARTILLERY; BAI: LISTICS ; EXPLOSIVES; Guxs, NAVAL; ORDNANCE; etc.