Macintosh, Charles (1766–1843)

Scottish manufacturing chemist who discovered that rubber could be dissolved in coal-tar naptha, producing a liquid that could be applied to fabric for waterproofing. This waterproof fabric, was used for raincoats – hence mackintosh. Other waterproofing processes have now largely superseded this method.

In 1797 Macintosh set up the first alum works in Scotland, and in 1799 invented a process for making bleaching powder. While investigating uses for the waste products of the new Glasgow gasworks in 1818, he noticed coal-tar naphtha dissolved India rubber. He experimented by sandwiching wool fabric with this substance to make a waterproof material, and invented the mackintosh. The material was hard in winter and sticky in summer, and awaited the discovery of vulcanization of rubber by Charles Goodyear in 1839 for success.