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203 A C C O U N T O F T H E C I R C U M S T A N C E S O F T H E C A M P A I G N A G A I N S T P I R A T E S I N 1 8 1 0 GUNPOWDER PRODUCTION APPENDIX II It is now generally accepted that the Chinese were the first to appreciate that a mixture of saltpetre, sulphur and charcoal produced a powder that burnt with unusual ferocity. Most substances burn by using the oxygen in the air to combine with fuel such as wood or coal in a process that is slow, as the supply of oxygen is relatively sparse. Saltpetre, or to give it its chemical name, potassium nitrate, provides a copious supply of oxygen. Ignition of gunpowder by the application of heat initially sets fire to the sulphur, which in turn sets fire to the charcoal. The whole process takes place very rapidly. The chemical reaction converts the ingredients to potassium sulphide, carbon dioxide gas and nitrogen gas. 2KNO3 + S + 3C → K2S + 3CO2 + N2 The reaction converts a small volume of solids into a large volume of gas. It does this very quickly so that the expansion of the gas has an explosive nature. The speed of the reaction is dependent on the proportions of the ingredients. The early Chinese mixtures probably used quite small proportions of saltpetre and consequently they would have burnt quite slowly. This would explain how its use first developed as a fire lance, with the powder taking five minutes or so to burn. Also as the combustion was not very explosive there was little danger to the soldier holding the fire lance. By the early sixteenth century the proportion of saltpetre had risen to about 50 percent and this gave gunpowder enough power to fire projectiles. By the time Macau was established the proportion used in Europe had risen to about 66 percent. The optimum proportions to give a powerful explosion are 75 percent saltpetre, 15 percent charcoal and 10 percent sulphur. A problem with early gunpowder was its durability. The ingredients are ground to a powder and manually mixed, but when the powder is transported or just left in store there is a tendency for the ingredients to separate and the powder becomes spoilt. Another problem is dampness and that is exacerbated by the fact that charcoal tends to attract water. When the moisture content of gunpowder rises above about one percent, it begins to lose its explosive power. One solution that was sometimes used was to transport the ingredients separately and just incorporate, or mix, them when needed. However, the solution that solved most of the problem was paradoxically moisture. 204 A P P E N D I X I I It was found that adding a little liquid, while incorporating, meant that the fine powder was made into a paste that could be formed into pellets, which when dried presented a smaller surface area to the air and kept the ingredients together. This “corned” powder was also found to be more powerful and some estimated it was 30 percent or more stronger. The size of the granules could be varied and the larger sizes were used for cannon with the smaller grains being for muskets and priming. This development took place in Europe in the late fifteenth century and with only minor improvements remained standard for the next three hundred years. In China there seems to have been less incentive to develop better powders. The reasons for this are not clear, but there was less need as most of China’s wars were fought either against internal rebels or against neighbours whose firearms were quite rudimentary. They must have been aware of the qualities of the European powders from their meetings with the Portuguese and other traders. However, it appears that the secrets of production were not passed on or the Chinese disdained to take notice. When Lord Macartney made his embassy to the Emperor Ch’ien-lung in 1793–1794 he was accompanied by Dr. Gillan who observed:1 There is no particular manufactory for making gunpowder in any part of the Empire. They have but few fire-arms and trust more to their sabres and bows and arrows than to their muskets, of which they seem not to understand well the advantages or management. They have, however, among their troops a few companies...

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