Chemistry and the Law

by Harold Goldwhite

In the previous column I traced the career of Humphry Davy to 1800. In 1801 he was invited by Count Rumford to a position at the relatively new Royal Institution in London. There Davy was eventually able to continue his own research, but first had to work up lectures on the chemistry of tanning, and with his usual thoroughness he did experiments on that subject; and on the applications of chemistry to agriculture. He later published a well-received book on that topic, and developed techniques of soil analysis.

In 1806 he was able to return to electrochemistry. He established some fundamental principles and in 1807 came the great breakthroughs. First was the isolation of metallic potassium from moist potassium hydroxide by electrolysis. The isolation of this astounding new metal – silvery, reactive with water and air – was recorded by Davy thus: “Capt. Expt. Proving the decompn. Of Potash”. It was capital. The previously undecomposed strong base had given him a new and extraordinary element. In short order followed metallic sodium, and calcium, barium, strontium and magnesium, though Berzelius had got there first with the alkaline earth metals.

This flood of new elements was one reason that Davy found Dalton’s new Atomic Theory unsatisfactory; Davy felt that nature should be simple. He toyed with the idea that all metals were in some way compounds of hydrogen. And he always preferred “experimental” chemical equivalents to Dalton’s “theoretical” atomic weights. In 1812 Davy published “Elements of Chemical Philosophy” which embodied his views. It included his elucidation of the nature of oxymuriatic acid, the gas obtained by the action of manganese dioxide on hydrochloric acid, which Davy showed contained no oxygen. He named it chlorine, after its color; it was yet another new element!

In 1812 two very significant events occurred; on April 8 he was knighted by the Prince Regent; he was now Sir Humphry. Three days later he married Jane Apreece, a young and wealthy widow. She was a social climber and most of Davy’s friends did not take to her. Davy’s researched continued; in October 1812 he isolated the dangerously explosive nitrogen trichloride and was injured by an explosion. His sight was initially affected, but he eventually recovered. In March 1813 he hired the young Michael Faraday as secretary and assistant and later that year the Davys and Faraday embarked on a European tour to France (Britain was at was with France at the time!), Italy, and Germany. In France Davy took the opportunity to undertake chemical work on a new substance isolated from seaweed, and declared it to be an analog of chlorine. He named the new element iodine. Gay-Lussac, who had been working on the same substance, was annoyed at what he viewed as trespass by the Englishman.

After returning from the Continent Davy was asked to work on a problem of national importance; explosions of fire-damp (mostly methane) in coal mines killed many miners who worked by the light of open lamps and candles. Davy undertook some basic research on the burning of methane and devised his safety lamp, in which the flame was surrounded completely by a cylinder of fine copper gauze. Fire-damp burned inside the lamp but the gauze conducted the heat so efficiently that there were no explosions. Davy gave his invention freely to the mining industry, and it has undoubtedly saved many lives.

Davy was now a statesman of science. He was active in the Royal Society and became its President, a position of much influence, in 1820. He continued doing scientific work, notably on developing sacrificial electrodes to protect the copper sheathing of ships. But he also continued to write on many other subjects – poetry and fishing. He had been an avid angler since boyhood. But his health began to deteriorate, perhaps due to his “heroic” experiments when he was young. Early in 1827 he was accompanied by his brother John – later his biographer – on a trip to the warmer climes of Italy. His condition was not much improved when he returned to London. He decided on another journey. In March 1828 he left for Austria and Italy. His condition grew worse and in early 1829 he was joined in Rome by his wife and his brother. The decision was made to return to England but on May 29, 1829, Humphry Davy died in Geneva, Switzerland, at the age of 50.

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