ABSTRACT
From the beginning of the seventeenth century onward, the development of the telescope and the microscope created a demand for lenses, and stimulated the invention of methods of grinding and polishing them. The somewhat similar methods of grinding specula for reflecting telescopes, as perfected by John Hadley, are also described by Robert Smith. A good idea of the methods employed during the eighteenth century for grinding and polishing telescope lenses is afforded by Smith in his Opticks. The eighteenth century witnessed the beginning of industrial chemistry, that is, the comparatively large-scale manufacture of chemicals for industrial use. The chemicals in greatest demand for industrial use in the eighteenth century were sulphuric acid and alkali; and they were required chiefly for use in the metal, bleaching, and dyeing industries. The manufacture of soda on an industrial scale was begun in 1791, and it developed rapidly. During the Napoleonic wars France found herself cut off from her usual supplies of crude soda.
