With respect to the pulverization of charcoal, the operation is so exceedingly simple, that we deem it unnecessary to notice it. It is obvious, that mortars, mills, &c. may be used, with fine or coarse sieves. For fire-works, charcoal is frequently pulverized in a leather sack, in the same manner as grained powder is reduced to meal-powder. It may be made either coarse or fine, to answer different purposes, by employing sieves of different kinds. Charcoal may be separated from nitre and sulphur, in gunpowder, by a simple process, which may be seen by referring to the section on gunpowder.
The quantity of carbon in coal, is directly proportionate to the quantity required for the decomposition of nitrate of potassa, a fact necessary to be considered in the theory of the action of charcoal in gunpowder. Thus, Mr. Kirwan found that, 12.709 of carbon are necessary to decompose 100 of nitrate of potassa. It will be easy to deduce the quantity of carbon, in a given weight of coal, from the quantity of nitrate of potassa it is capable of decomposing. The experiment is made very readily by fusing in a crucible, five hundred or more grains of nitre, and when red-hot projecting by degrees the powdered coal on the nitre. When the detonation produced by one projection of coal has ceased, add a new portion till it produces no farther effect.
Charcoal may be made intensely black, resembling ivory black, according to M. Denys-de-Montfort, (Bibliothèque Physico-Economique, for March 1815,) by pulverizing it very fine, mixing it with wine lees, and drying the mixture, and then subjecting it to a strong heat in a covered crucible, or other vessel.
Having remarked, that the quality of gunpowder depends upon the purity of the materials, of which it is formed, and that they should be prepared in a state of purity; the subject that will now particularly claim our attention, is the proportions of the ingredients, their mixture, and the final preparation of gunpowder for use. To this, we purpose to add, the theory of its explosive effects, the different modes of proving it, and the experiments necessary to determine the quality of its respective ingredients, on all which we will be as brief as the importance of the subjects will admit. Previously, however, it may be interesting to notice the history of gunpowder, the invention of which has so completely changed the art of war.
The history of gunpowder has been fully treated by many writers of eminence; but by none more largely, and, at the same time, more satisfactorily than by the French. Beckman, in his History of Inventions, is full on this subject. Our purpose is not to go into details, as it would enlarge our volume, to the exclusion, perhaps, of other and more important matter. We shall, therefore, confine ourselves to a few facts and observations.
Notwithstanding much has been written on the subject, the original invention of gunpowder seems to be in obscurity. By whom, and at what time it was invented, is a question not fully settled. It is said to have been known in the east from time immemorial, and whatever claim Roger Bacon, who died in 1292, may have had to the discovery, or that he knew the properties of gunpowder, it is certain, that the use of fire-arms was then unknown in Europe.
Professor Beckman, who examined all the authors extant on the origin of gunpowder, is of opinion, that it was invented in India, and brought by the Saracens from Africa to the Europeans, who improved the preparation of it, and employed it in war, as well as for small arms and cannon.
M. Langles, who read a memoir on this subject to the National Institute, in 1798, observes, that the Arabians obtained a knowledge of gunpowder from the Indians, who had been acquainted with it from the earliest periods. The use of it was forbidden in their sacred books, the veidam or vede. It was employed in 690 at the battle near Mecca. As nitre was employed in all probability in the Greek fire, invented about the year 678, it is supposed, that that composition gave rise to the invention of gunpowder.