We find Theophrastus (315 B.C.) describing... the manufacture of white lead... "lead is placed in an earthen vessel over sharp vinegar, and after it … - J. R. Partington

The results of a scrutiny of the materials of chemical science from a mathematical standpoint are pronounced in two directions. In the first we observe crude, qualitative notions, such as fire-stuff, or phlogiston, destroyed; and at the same time we perceive definite measurable quantities such as fixed air, or oxygen, taking their place. In the second direction we notice the establishment of generalizations, laws, or theories, in which a mass of quantitative data is reduced to order and made intelligible. Such are the law of conservation of matter, the laws of chemical combination, and the atomic theory.

An explanation of a phenomenon is regarded, apparently instinctively, as the most general possible when it is a mechanical explanation. The "mechanism" of the process is the ultimate goal of experiment. Now this mechanism in general lies beyond the range of the senses; either by reason of their limitations, as in the case of the atomic structure of matter, or by the very nature of the supposed mechanism, as in the theory of the ether. The only way to bridge the gap between the machinery of the physical process and the world of sense-impressions is to think out some consequence of that mechanism. This we will call the hypothesis. The hypothesis, resting still on the mechanical basis, is yet beyond the range of direct experimental investigation; but if, by mathematical reasoning, a consequence of the hypothesis can be deduced, this will often lie within the range of experimental inquiry, and thus a test of the soundness of the original mechanical conception may be instituted.

Some recent short publications on Chinese gunpowder and firearms are misleading... I have had valuable assistance from Dr. J. Needham... If the dates of the texts are correct, the discovery of the use of saltpetre in explosives and the development of gunpowder are to be sought in China from the eleventh century. The history of gunpowder is associated with that of saltpetre, no comprehensive account of which was available.