Charles Macintosh, inventor of the ‘Mackintosh’ raincoat, died on the 25th of July, 1843.
Charles Macintosh was a Scottish chemist and inventor whose name is known the world over from the eponymous raincoat. Look it up in a dictionary, but remember to check the spelling; it has a ‘k’ inserted, following the ‘sasunnach’ convention. Interestingly, the first notable use of Macintosh’s rainproof cloth was by Sir John Franklin’s 1924 Arctic Expedition. Of course, his cloth became both indispensable and famous as without Macintosh there would have been no imagery for ‘Aqualung’ nor, indeed, an unforgettable prop for ‘Lieutenant Columbo’.
Although Macintosh is primarily remembered for his patented process of using rubber dissolved in coal tar naphtha to produce a double textured, waterproof cloth, he also made a series of important contributions to the field of industrial chemistry. At one time, he had a plant in Glasgow for producing ammonia from coal gas waste and he introduced the manufacture of lead and aluminium acetates to Britain. Macintosh also made advances in cloth dyeing processes and helped develop a method for making bleaching powder. In addition, he patented a way of using a current of coal gas to provide carbon content when converting malleable iron to steel. Unfortunately, the process wasn’t commercially successful, because he wasn’t able to solve the problem of keeping the furnace gas-tight. Macintosh also worked with James Beaumont Neilson on his hot blast process to produce high quality cast iron.
Charles Macintosh was born on the 29th of December, 1766, in Glasgow. His father was a Highlander, who had moved to Glasgow to set up a ‘manufactory’ of the purple dying powder called ‘cudbear’, obtained from various lichens and capable of colouring wool and silk. In the 1760s, George Macintosh & Co was located ‘by the Craig’s Park’ in what is now known as Dennistoun. Although he was supposed to follow his father into the business, Charlie gained an interest in the processes employed in the factory and that developed into his passion for science and chemistry. After leaving school, Charlie attended University in Glasgow and became a student of chemistry under Joseph Black at Edinburgh. He was then employed as a clerk with a Glasgow merchant, but he found the time to study science, particularly chemistry.
However, by the time he was twenty, Charlie had resigned and opened a plant in Glasgow for the manufacture of chemicals, particularly sal ammoniac (ammonium chloride) and Prussian blue dye. He also traded white lead, a constituent of paint, with the Netherlands. Later, in 1797, he established Britain’s first alum works at Hurlet, in Renfrewshire, for the manufacture of aluminium acetates. He had found a source of the alum in waste shale from coal mines. Macintosh then entered into a successful partnership with several notable characters, including Charles Tennant, who ran a cloth and paper bleaching business in Paisley, James Knox, William Couper and Alexander Dunlop. Tennant also had a chemical works at St. Rollox, near Glasgow, where Charlie helped him develop a dry bleaching powder made from chlorine and slaked lime. Tennant patented the process in 1799 and Macintosh remained a key figure in Tennant Knox & Co. until 1814. The success of the plant made it for a while the largest chemical works in Europe with reputedly the tallest chimney in the world.
Macintosh inherited the cudbear factory on his father’s death and armed with a share of the profits from the bleaching business was seeking ways to invest his wealth. Around that time, in 1817, the Glasgow Gas Light Company was established and Macintosh became keen to find a means of using the waste products from the coal gas industry. One such product was coal tar naptha, a volatile liquid hydrocarbon mixture, which was a by-product of distilling tar. Although it could be used in flares, Macintosh worked hard at experimenting to find more ways to yield value from the tar waste and discovered it was possible to dissolve india-rubber in naptha. That wasn’t a novel idea, but Macintosh’s brilliance lay in applying his knowledge of textiles, gained as a dye-maker, to use the liquid rubber for waterproofing fabrics. In June 1823, Macintosh patented his process using a solution of india-rubber in naphtha sandwiched between two layers of woolen cloth. The two-layer concept was also ingenious as the solution remained sticky if left exposed. His patent, No. 4,804, described how to ‘manufacture for rendering the texture of hemp, flax, wool, cotton, silk, and also leather, paper and other substances impervious to water and air’.
Macintosh began the manufacture of waterproof textiles, initially in Glasgow and later in Manchester, in 1824, after he went into partnership with the industrialist, Hugh Hornby Birley, who was a director of the Manchester Gas Works and owner of a cotton mill. The result was a factory producing waterproof material marketed under the name ‘Mackintosh’ – with the extra ‘k’. The rainproof cloth was used by the British army and navy, who wouldn’t have minded the smell, and the Franklin Arctic expedition. It was introduced to the general public as the ‘Mackintosh’ – the world’s first raincoat.
In 1825, Macintosh granted a licence to Thomas Hancock, the ‘father of the UK rubber industry’, to manufacture his patented ‘waterproof double textures’. Hancock was an important contributor to the development of Macintosh’s material. He became Macintosh’s partner in 1831, and after merging his own company into the business, ran Charles Macintosh & Co. The discovery of vulcanization, initially by Charles Goodyear in 1839, and separately by Thomas Hancock in 1843, the year Charles Macintosh died, completely altered the fortunes of the company. That process solved several problems inherent in the original material, particularly its susceptibility to temperature changes. Further developments led to single texture fabrics, vulcanized using sulphur chloride, and an award-winning appearance at the Great Exhibition of 1851. Charles Macintosh & Co. continued until 1923, when it was taken over by Dunlop.
Charles Macintosh was elected a fellow of the Royal Society in 1823, in recognition of his various chemical discoveries. He died on the 25th of July, 1843, at Dunchattan in Scotland and was buried in the graveyard of Glasgow Cathedral, where a stone in the north wall marks his grave. Charles Macintosh with a ‘k’ and his eponymous invention are as much a part of everyday vocabulary as sandwich, biro, hoover and google; even if posterity continues to misspell his name.