Editing James Watt (section)

===Chemical experiments===
From an early age, Watt was very interested in chemistry. In late 1786, while in Paris, he witnessed an experiment by [[Claude Louis Berthollet]] in which he reacted [[hydrochloric acid]] with [[manganese dioxide]] to produce [[chlorine]]. He had already found that an [[aqueous solution]] of chlorine could [[bleach]] textiles, and had published his findings, which aroused great interest among many potential rivals. When Watt returned to Britain, he began experiments along these lines with hopes of finding a commercially viable process. He discovered that a mixture of salt, manganese dioxide and [[sulphuric acid]] could produce chlorine, which Watt believed might be a cheaper method. He passed the chlorine into a weak solution of [[alkali]], and obtained a [[Turbidity|turbid]] solution that appeared to have good bleaching properties. He soon communicated these results to James McGrigor, his father-in-law, who was a bleacher in Glasgow. Otherwise, he tried to keep his method a secret.<ref>Hills, vol. 3, ch. 4.</ref>

With McGrigor and his wife Annie, he started to scale up the process, and in March 1788, McGrigor was able to bleach {{Convert|1500|yd|ft|abbr=off}} of cloth to his satisfaction. About this time, Berthollet discovered the salt and sulphuric acid process, and published it, so it became public knowledge. Many others began to experiment with improving the process, which still had many shortcomings, not the least of which was the problem of transporting the liquid product. Watt's rivals soon overtook him in developing the process, and he dropped out of the race. It was not until 1799, when [[Charles Tennant]] patented a process for producing solid bleaching powder ([[calcium hypochlorite]]) that it became a commercial success.

By 1794, Watt had been chosen by [[Thomas Beddoes]] to manufacture apparatuses to produce, clean and store gases for use in the new [[Pneumatic Institution]] at [[Hotwells]] in [[Bristol]]. Watt continued to experiment with various gases, but by 1797, the medical uses for the "[[factitious airs]]" (artificial gases) had come to a dead end.<ref>Hills, vol. 3, pp. 152–58.</ref>[[File:Watt apparatus 3.JPG|thumb|Scientific apparatus designed by [[Boulton and Watt]] in preparation of the [[Pneumatic Institution]] in Bristol]]