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Friday, 25 July 2014

Having started as a clerk; this MACINTOSH followed his passion in chemistry leading to invention of first waterproof fabric/!!!

Charles Macintosh (29 December 1766 – 25 July 1843) was a Scottish chemist and inventor of waterproof fabrics. The Mackintosh raincoat is named for him. Macintosh was born in Glasgow, and was first employed as a clerk. By age 19, he instead pursued his interest in chemistry and science derived from his father, George Macintosh who was a well-known and inventive dyer. Charles was prepared with university studies at Glasgow and as a student of Joseph Black at Edinburgh. 

He devoted all his spare time to science, particularly chemistry, and before he was twenty resigned his clerkship to take up the manufacture of chemicals. In this he was highly successful, inventing various new processes. His experiments with one of the by-products of tarnaphtha, led to his invention of waterproof fabrics, the essence of his patent being the cementing of two thicknesses of cloth together with natural (India) rubber, the rubber being made soluble by the action of the naphtha.

By the time he was twenty, Charles had opened a plant in Glasgow to produce sal ammoniac (ammonium chloride) and Prussian blue dye. He also introduced the manufacture of lead and aluminum acetates to Britain, and developed new processes to dye cloth. In 1797, he established Scotland’s first alum works at Hurlet, Renfrewshire. He found a source of the alum in waste shale from coal mines. Additional chemical works followed later.

In 1818, while analysing the by-products of a works making coal gas, he discovered dissolved indiarubber. He joined two sheets of fabric together with this solution, allowed them to dry, and discovered that the new material could not be penetrated by water - the first rainproof cloth. For his various chemical discoveries he was, in 1823, elected a fellow of the Royal Society. In 1828, he became a partner with James Beaumont Neilson in a firm to exploit the latter's patent for the hot blast blowing of blast furnaces, which saved considerably on their fuel consumption.

In 1823, while trying to find uses for the waste products of gasworks, Macintosh noted that coal-tar naphtha dissolved india rubber. He then took wool cloth, painted one side of it with the rubber preparation, and placed another thickness of wool cloth on top, thereby producing a waterproof fabric. Soon after he began the manufacture of coats and other garments. But problems developed. In the process of seaming a garment, tailors punctured the fabric, allowing rain to penetrate; the natural oil in woollen cloth caused the rubber cement to deteriorate; and, in the earlier years, the garments became stiff in winter and sticky in hot weather. The mackintosh, as it came to be known, was greatly improved when vulcanized rubber, which resisted temperature changes, became available in 1839.

Macintosh married, in 1790, Mary Fisher, daughter of Alexander Fisher a merchant of Glasgow. Charles Macintosh died in 1843 at Dunchattan, Scotland, and was buried in the churchyard of Glasgow Cathedral.

A yeast factory which Macintosh set up in 1809 failed because of opposition from London brewers. Meanwhile, he continued to buy all the ammonia and the tar waste byproducts from the Glasgow coal-gas works. He utilized the ammonia in the production of cudbear, a useful dye extracted from various lichens. By varying the choice of mordant used with this dye, manufacturers could colour textiles in a range of shades from pink to blue. The tar could be distilled to produced naphtha - a volatile, oily liquid hydrocarbon mixture. Although this could be used in flares, from 1819, Macintosh continued to experiment to find more ways to utilize naphtha, so that the original tar waste could yield more value.

In June 1823, Macintosh patented his process using a solution of india-rubber in naphtha soaked between two layers of cloth forming a sandwich that was pressed together. The rubber interior provided a layer impermeable to water, though still flexible. 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.” (The sandwich-type construction was not totally new, for it had been devised by Spanish scientists to make leak-proof containers for mercury, and also Charles Green in 1821 had made a balloon envelope that applied the same principle.)

In another application of his inventiveness, Macintosh developed improved methods of iron production, which was much faster than the existing methods. He patented a method for converting malleable iron into steel (1825) in which the iron was raised to white heat in a current of coal gas which provided a carbon content. The process was unsuccessful in commercial application because of the problem involved in keeping a furnace gas-tight. He then assisted Beaumont Neilson in bringing hot blast into use in blast furnaces (1828). By introducing hot air into the furnace, instead of cold air, the smelting process was made more efficient. In return, he was given a share in Beaumont’s patent. This was more of a loss than a gain because of protracted litigation concerning the patent that lasted until 1843.