Charles Macintosh

There are two famous Glasgow Mac(k)intoshes, and this is the other one. Charles Macintosh — born a century before the architect Charles Rennie Mackintosh, and no relation — was one of the most inventive industrial chemists of his age, a serious figure in the chemistry that underpinned Glasgow’s textile and iron industries. But he is remembered by the whole world for a single practical triumph: the waterproof coat that carries his name, born of a Glaswegian’s refusal to let anything go to waste.

The Dyer’s Son

He was born in Glasgow on 29 December 1766, the son of George Macintosh, a Highlander who had come to the city and built a works in the Dennistoun area manufacturing cudbear — a violet-red dye extracted from lichen, then in great demand for colouring the cloth of a textile city. Charles was set to a merchant’s counting-house as a clerk, but chemistry had him early: he spent his spare hours at it, and before he was twenty gave up the clerkship altogether, studying under the great Joseph Black — the discoverer of carbon dioxide, and James Watt’s friend and backer — and setting up as a manufacturing chemist in his own right.

The Chemist

Long before the raincoat, Macintosh was a formidable industrial innovator. In his teens he was making sal ammoniac and Prussian blue from the by-products of Glasgow’s works; by his early thirties he had founded Scotland’s first alum works at Hurlet in Renfrewshire, cleverly using waste shale from the coal mines as his raw material. In 1799 he went into partnership with Charles Tennant to make bleaching powder at the St Rollox works north of the city — a product that revolutionised the bleaching of cloth and paper and helped make St Rollox, for a time, the largest chemical works in the world. He introduced the manufacture of lead and aluminium acetates to Britain, and later devised a steel-making process that led the Glasgow engineer James Beaumont Neilson toward the hot-blast furnace of 1828, one of the foundations of the Scottish iron industry — though years of patent litigation robbed both men of the profits.

The Waterproof Cloth

The invention that made his name came, fittingly for Glasgow, from turning waste into worth. Experimenting around 1818 with coal-tar naphtha — a by-product of the city’s new gasworks that nobody wanted — Macintosh found that it dissolved india rubber. He painted the rubber solution onto one piece of cloth, pressed a second on top, and produced a fabric that rain could not penetrate; he patented it in 1823, the same year the Royal Society elected him a Fellow. Early ‘mackintoshes’ had their troubles — tailors punctured the seams, the natural oil in wool rotted the rubber, and the coats turned stiff in winter and sticky in summer — but the problems were solved, the British Army and police adopted the garment, and the mackintosh entered the language. Nobody has ever satisfactorily explained the extra ‘k’.

More Than the Mac

Macintosh kept up his chemistry, attending university lectures into his old age, and died on 25 July 1843 at Dunchattan, by then swallowed into the growing city he had helped to build. He was buried at Glasgow Cathedral. Two centuries on, the coat is still made and still called by his name, and in 2016 the world’s largest search engine marked the 250th anniversary of his birth — a rare honour for a chemist, and a fitting one for the Glaswegian who made the rain bearable.

His page belongs in this chapter as a reminder that Glasgow’s genius was practical as well as grand: the same instinct that turned tobacco into fortunes and the Clyde into a shipyard turned gasworks tar into the coat on the world’s back.

The Glasgow connection

Macintosh’s Glasgow is the industrial city he served: the Dennistoun (Dunchattan) ground where his father’s cudbear works and his own home stood, the vanished St Rollox chemical works whose bleaching powder he helped invent — and his grave in the burial ground of Glasgow Cathedral, the resting place of the chemist whose name the world still wears in the rain.