Charles Macintosh

The Scottish chemist and inventor Charles Macintosh (1766–1843) devised the first process for mass-producing waterproof fabric. The “mackintosh,” a commonly used synonym for raincoat, is still in use in British English.

The usefulness of the mackintosh has somewhat obscured Charles Macintosh's other discoveries, which were numerous. He set up Scotland's first factory devoted to the manufacture of alum (a sulfate), and he made important advances in the process of chlorine bleaching. Macintosh also found a fast method for converting iron to steel, and he helped develop a process for using a hot blast furnace to produce high-quality iron. In addition to contributing to the development of high-quality fixed dyes, he made several discoveries in the field of pure chemistry. In 1829, Macintosh and several partners joined forces to manufacture and market the Macintosh waterproof coat and a range of other products; the company continued to prosper even after the first wave of waterproof raincoat designs began to taper off. He was one of the most inventive and experimentally minded scientist-industrialists of the early 19th century.

Studied Industrial Chemistry

Macintosh was born in Glasgow, Scotland, on December 29, 1766. His father, George Macintosh, was raised in the Scottish Highlands and moved to Glasgow as a young man. During Macintosh's youth, George set up a factory manufacturing a violet-red dye called cudbear that was made from lichens. Macintosh, therefore, grew up around industrial chemicals. He attended elementary school in Glasgow and then, as the family prospered, was sent to a boarding school in Catterick Bridge in England's Yorkshire region. The plan was for Macintosh to become an accountant, and he attended a university in Glasgow, intent on studying toward that major. However, science remained his passion and he sought out lectures by leading scientists such as Joseph Black, the discoverer of magnesium and carbon dioxide. By the time he turned 20, it was clear that Macintosh would pursue a career in industrial chemicals.

In following that career, his successes were early and rapid. In 1786, he introduced to Britain a manufacturing process for the dye fixative lead (II) acetate, a toxic compound also known as sugar of lead that had been developed in the Netherlands. He was also the first to bring aluminium acetate manufacturing into use in Great Britain. Around the same time, he opened a Glasgow factory to produce ammonium chloride and a dye called Prussian Blue; the factory soon developed several new dyeing processes. In 1790, Macintosh married Mary Fisher, daughter of a merchant entrepreneur and a likely descendant of Scottish royalty. During their marriage, the couple had three children.




Charles Macintosh





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One of Macintosh's most important breakthroughs involved not dyeing textiles but rendering them white: he partnered with Charles Tennant, owner of a chemical plant in St. Rollox near Glasgow, to develop a bleaching powder. Until then, raw cotton and linen clothing was bleached by boiling it in an alkali solution and then exposing it to sunlight, a process that could take months. Tennant developed a chlorine-lime solution, and the two men finally patented a powder made from dry slaked (crumbled) lime. This powder was easily transported, and its commercial success eventually made the St. Rollox factory the largest chemical plant in Europe. Macintosh became wealthy, and he continued to work with the plant until 1814. Bleaching powder essentially similar to that invented by Macintosh and Tennant was used in making paper and cloth until the introduction of liquid bleach in the 1920s.

Perfected Production of Waterproofing

Beginning in 1819, Macintosh began experimenting with new ways to exploit the materials currently carted away from the Glasgow coal and gas facility. Naphtha, he discovered, would partially dissolve India rubber, transforming it into a malleable substance that could be used to coat one side of a length of woolen cloth. When two layers of fabric sandwiched this coating, a waterproof textile resulted. Macintosh was not the first person to create a waterproofing technology—in Spain, a rubberized substance had been used to make leakproof containers for mercury—but his was the first method suited to large-scale industrial production. In 1823, he filed patent No. 4,804, claiming rights to his method of “manufacture for rendering the texture of hemp, flax, wool, cotton, silk, and also leather, paper and other substances impervious to water and air.”

Although a few problems remained to be overcome—tailors complained that when they punctured the cloth with a needle, it lost its waterproof quality—Macintosh quickly found that he had a hit on his hands. He established a factory in Glasgow and then formed a second in the industrial city of Manchester, England. After he began to receive large orders from the British military, the operation prospered. Another early customer was the British Admiralty, which was then planning an expedition to the Arctic to be headed by Captain John Franklin; this expedition succeeded in reaching the mouth of the Mackenzie River and the Great Slave Lake in what is now northern Canada. The Manchester factory still exists and is now owned by the Dunlop corporation.

Coats made of Macintosh's material were soon marketed as mackintoshes (the point at which the extra “k” was added is unknown), and the name became familiar enough that by 1840 it was used by American poet Henry Wadsworth Longfellow. An unsuccessful 1836 patent infringement lawsuit against Macintosh only helped to publicize the product further and cemented use of the misspelled name of its inventor.

Patented Steel Production Method

Macintosh's inventions did not end with the mackintosh. In the mid-1820s he developed more efficient methods of iron production, and in 1825 he patented a procedure for converting iron into steel. The procedure involved heating iron in coal gas until it was white-hot, introducing carbon to the mix. Furnace technology of the time was not advanced enough to keep the furnace gas-tight, so this method was never used on a large scale, but it was a precursor to the more efficient production of steel that would evolve later in the 19th century. Macintosh also refined the operation of blast furnaces by applying the so-called hot-blast technique developed by engineer James Beaumont Nielson.

Macintosh's contribution to blast-furnace technology turned out to be more a liability than an advantage: Nielson offered to share the patent with Macintosh, but that put both men on the defensive when the patent became embroiled in litigation. Although he continued work on his waterproof fabric, the need for rainproof outerwear by the masses dropped off when regular railway service was introduced in England in the 1830s. Macintosh responded to this change in market demand by developing new products, including rubber shoes and cushions. As energetic a businessman as he was an engineer, he traveled as far as the southern Italian kingdom of Sardinia while promoting his products. He spoke and wrote French fluently and personally conducted a large volume of commercial correspondence with French buyers.

Respected within the scientific community for his work as a pure chemist, Macintosh was elected to the Royal Society, England's leading scientific body, in 1824. Determined to keep current with developments in chemistry, he attended lectures at the University of Glasgow well into his later years. Macintosh died in Dunchattan, Scotland (now part of the city of Glasgow), on July 25, 1843. His son George wrote his biography four years later.

Books

Periodicals

Christian Science Monitor, September 15, 2004, Nancy M. Kendall, “Facing the Elements,” p. 18.

Online

Science on the Streets, http://scienceonstreets.phys.strath.ac.uk/new/Charles_MacIntosh.html (November 1, 2017), “Charles Macintosh.”

Today in Science History, https://todayinsci.com/M/Macintosh_Charles/MacintoshCharlesBio.htm (November 1, 2017), “Charles Macintosh.”□

(MLA 8th Edition)