The express period when nitrum was first discovered is extremely uncertain; but that this nitrum is an alkaline salt, there is little difficulty in proving. It has, indeed, been conjectured that it was a component part of the Greek fire, invented about the year 678, which has been generally believed to be the origin of gunpowder. From the oldest prescriptions which have been found, and which is said to be that given by the Princess Anna Commena, in which, however, only resin, sulphur, and oil are mentioned, saltpetre does not appear.

It is believed by an author very well qualified to form a judgment on the question, that the first certain account we have of saltpetre by that express name, occurs in the oldest account of the invention of gunpowder, which, according to him (Professor Beckmann) occurred in the thirteenth century. Dr. Rees, in his Cyclopedia, expressly says, about the year 1320; and that it was first used by the Venetians employed against the Genoese in 1380; also that it was first in Europe at a place now known as Chrogia, against Laurence de Medicis; and the last named authority adds, “That all Italy made complaint against it, as a contravention of the law of arms.” Dr. Rees gives the following recipe for its manufacture, without distinguishing the proportionate parts:—“A composition of nitre, sulphur, and charcoal, mixed together, and usually granulated.” He describes its effects by observing, that “it easily takes fire, and when fired, rarifies and expands with great vehemence by means of its elastic force;” also that “it may be made without nitre, by means of marine acid.”

We have two accounts preserved to us of the original of this invention. The first of which was given by our illustrious countryman, Roger Bacon, called the Wonderful Doctor, who died A.D. 1278; previous to which period, gunpowder must have existed. The other account is by Albertus Magnus, in a work published in 1612.

It is said to be doubted whether Albertus was the author of the book which bears his name; but that he, whoever he may have been, and Bacon, are presumed to have taken their information from the same identical source. About the period of the invention of gunpowder, it appears the art of making the Greek fire began to be lost. In the works of Roger Bacon, the term occurs three times. According to Casiri, the term pulvis nitratus, is to be found in an Arabic MS. the author of which existed about 1249. If the work of Geber, De Investigatione Perfectionis, be genuine, and if this writer lived, as has been thought, in the eighth century, it would be the oldest where saltpetre is mentioned, in a prescription for an aqua solutiva, which appears to be almost aqua regia.

We are inclined to believe, however, from various authorities, that gunpowder was invented in India, as it was proved in a paper read before the French National Institute, by M. Langles, 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 in war is said to have been prohibited them in their sacred books. It was employed in 690 at a battle near Mecca, by the Arabians. It was brought by the Saracens from Africa to the Europeans, who improved the preparation, and first discovered various ways of employing it in war. In no country could saltpetre and its various uses be more easily discovered than in India, where the soil is so rich in nitrous particles that nothing is necessary but lixiviation to obtain saltpetre; and where this substance is so abundant, that almost all the gunpowder used in different wars, with which European sovereigns have tormented themselves, burdened their subjects with intolerable taxes, and cursed the world from its invention—has been made from Indian saltpetre. Had not saltpetre been known previous to the thirteenth century, neither could gunpowder or aquafortis have existed; and for the best of all reasons, that neither of them could be made without saltpetre or nitre. But should it appear that this neutral salt was known in India long prior to that period, and used by Indians as well as Arabians before they were employed by Europeans, and considering the former to have practised chemistry previous to the latter; should this have been proved, perhaps a similar proof will necessarily await upon the articles aquafortis and gunpowder. Because if this affirmation be established, it will be discovered that Europeans knew nothing of aquafortis until after the Arabian chemists.

Probability appears to favour the idea, that at or about the twelfth century the accumulated number of consequents, from the improvement in European science, the arts we now possess were introduced into our catalogue, i.e., nitre, aquafortis, and gunpowder.

After the period that saltpetre became necessary to governments for the manufacture of gunpowder, they endeavoured to obtain it at a cheap rate; and for that purpose were guilty in some countries of the most violent and oppressive measures, intruding upon private property of every description to furnish it, hunting for the effervescence even in old walls, to the great annoyance of individuals. But after repeated acts of the most flagrant oppression from the public officers, and from farmers, to whom this iniquitous practice was entrusted, they could not procure a sufficiency; but were obliged to have recourse to traffic in India for that purpose.