In discussing the treatise above mentioned, there is a naïve expression of our authors, who, in remarking the necessary slow combustion of these compounds from the imperfections of the processes of manufacturing saltpetre, also given in the same book, say:—"One sees how much there is that is providential in the progress of human invention. If man had, in the first instance, a powder as strong as at present, he would probably have been unable to master this force, or to use it with suitable instruments, and the discovery would have remained without application. We see that, thanks to the primitive impurity of the saltpetre, man employed mixtures of it with sulphur and charcoal, which produced a force suitable for throwing to short distances feeble parcels of incendiary matter. This force increased little by little, as men became better able to refine saltpetre, and ends by enabling them to employ it for throwing projectiles."
We have frequently heard the word providential applied in a strange manner; but this is one of the most novel views of providential intervention we happen to have met with. The quiet gravity with which Providence is assumed to have interfered in favour of the progress of destructive implements, is about as instructive an instance of the unconscious devotion of an author to his speciality as could easily be selected.
In the treatise of 1561 are some receipts, assumed to be taken from works of an earlier date, in which saltpetre, sulphur, and charcoal, are submitted to a considerable degree of heat. The following is one:—"Take of saltpetre 100 lbs., sulphur, 25 lbs., charcoal, 25 lbs., put them altogether, and make them boil well, until the whole be well united, and then you will thus have a strong powder." Mixed in these proportions, and submitted to such a temperature, the chance of explosion is very great; and, as our authors observe, "the essential fact of the tradition respecting the invention of gunpowder is confirmed;" or rather, strictly speaking, the probability of its truth is strengthened. We therefore do not see very clearly why they should be anxious to divest Schwartz of the merit of its discovery, while they produce arguments to show the probability of the discovery being so made. The results of these arguments would only tend to show that the tradition is not sufficiently explicit, in not stating why the three ingredients were mixed together; and Schwartz would, according to this view, be regarded as the first who remarked and applied, or suggested the application of gunpowder, as supplying an explosive projective force.
Though the probabilities of the use of gunpowder, as an explosive compound, being suggested by accidents occurring in the manufacture of combustible compounds, are thus shown to be very great, the actual step, if step it were, still remains in obscurity. Most probably, like many other inventions, the fact was observed again and again with different degrees of accuracy and different resulting suggestions; until, at length, growing intelligence seized on it, and increasing facility of publication rendered its development more rapid and general. The actual date of its general introduction or use in war is still uncertain. Schwartz's discovery is stated by Kircher at 1354; but gunpowder is stated to have been used at the siege of Stirling in 1339; in Denmark in 1340; in Spain in 1343; at Cressy in 1346; at the siege of Calais in 1347.
Without entering into the critical discussions which the vagueness of the historical records of these periods might tempt, we can scarcely be far wrong in setting down the general introduction of gunpowder during the first half of the fourteenth century, although any attempt to specify, from existing data, the exact date of its invention, would be vain. With regard to its connexion with Greek fire, we may sum up by stating, that during different periods, extending from the eighth to the fourteenth century, combustible matters, in which saltpetre was one ingredient, have been used; and that the term Greek fire has been, at various times within this period, applied to them. Although it does not necessarily follow that the Greek fire alluded to in the more recent works was identical with the Greek fire of an earlier period, yet the probability is strong that there was at least a striking analogy in effect, or the name would not have been used. There is, moreover, some internal evidence of community of origin in these various receipts, when we find that in different parts of the world, in China, in Arabia, and Greece, one general characteristic ingredient is present, viz., nitre; when also the history and progress of chemistry have taught us that no substance, other than nitre or a salt of nitric acid, has ever been, or is now known, which would produce similar effects, (for the comparatively recent discovery of the chlorates would produce effects of detonation by friction or percussion, of which we find no records,) there can, we think, be little doubt that Greek fire was of the same chemical character as gunpowder; that it passed by a transition, which may have been in particular cases more or less sudden, but which upon the whole was gradual, into gunpowder; and that the history of the progress of one of these manufactures is, in fact, the history of the progress of the other. In this history there are still many gaps to be filled up, many errors to be rectified.
The book of Messrs Reinaud and Favé, though somewhat inartificially arranged, has given to the public much valuable information; but there is still room for an elaborate and well-digested treatise on the subject, in which the whole progress of pyrotechnic invention may be arranged in chronological order, and more lucidly expounded than are antiquarian matters in general. This is a task, however, which few, if any, are capable of undertaking, as it requires for its successful execution a combination of extensive antiquarian, chemical, and philological acquirements. In the mean time, our authors may say, and we say with them,
"Si quid novisti rectius istis,
Candidus imperti; si non, his utere mecum."