The value of the voltaic pile as an analytical agent was nowhere more quickly appreciated than in England. In the hands of Humphry Davy its application to the analysis of the alkalis and alkaline earths led to discoveries of the greatest magnitude.
Humphry Davy was born in Penzance in 1778. In the course of his studies for the profession of medicine he was attracted to chemistry; and he became chemical assistant to Dr. Beddoes, a former teacher of chemistry at Oxford, but then living at Clifton, near Bristol. While in the capacity of assistant and operator in Beddoes’s Pneumatical Institute, Davy discovered the intoxicating properties of nitrous oxide (so called laughing gas), which brought him into prominence and led to his engagement by the managers of the newly-created Royal Institution in London as lecturer in chemistry in succession to Garnett. He early began to experiment on galvanism, and soon succeeded in developing the fundamental laws of electro-chemistry; and in 1807 he effected the decomposition of potash and soda by the application of voltaic electricity—thereby establishing, what indeed had been surmised previously, that the alkalis are compound substances. He subsequently proved that this was also the case with the alkaline earths. Davy thus added some five or six metallic elements to those already known.
These discoveries, perhaps the most brilliant of their time, afforded additional evidence of the invalidity of Lavoisier’s assumption that oxygen, as the name implies, was the “principle of acidity.” The surmise, in fact, was already disproved by the case of water—a neutral substance and devoid of all the recognised attributes of an acid. It was still further disproved by the cases of potash and soda—strongly alkaline compounds.
Additional evidence was adduced by Davy in demonstrating, in 1810, that the so-called oxymuriatic acid, the dephlogisticated marine acid discovered by Scheele, contained no oxygen, but was a simple, indivisible substance. For the old designation, which connoted a compound body, he substituted the name chlorine, in allusion to the characteristic colour of the element. In the course of his investigation on this substance he discovered the penta- and trichloride of phosphorus, chlorophosphamide and chlorine peroxide. He was also the discoverer of telluretted hydrogen and an independent discoverer of nitrosulphonic acid.
Sir Humphry Davy.
From a painting by Lawrence in the possession of the Royal Society.
He worked on iodine and the iodates, on the diamond, on the so-called fuming liquor of Cadet, on nitrogen chloride, and on the pigments of the ancients. Lastly, he invented the miner’s safety lamp, with which his name will always be associated, effecting thereby what was practically a revolution in coal-mining. He became President of the Royal Society in 1820, and died at Geneva on May 29th, 1829, in the fifty-first year of his age. Davy was a singularly gifted man, of great mental vigour and imaginative power; quick, lively and ingenious; an eloquent teacher and a daring and brilliant experimenter.
Another noteworthy name in the chemical history of this period is Wollaston. William Hyde Wollaston, born at East Dereham, in Norfolk, in 1766, was educated at Cambridge with a view to the profession of medicine, but, failing to secure a practice, he devoted himself to the pursuit of science, and especially to optics and chemistry. He devised a method of working platinum, and was the first to make known the existence of palladium and rhodium. He was one of the most ingenious and acute analysts of his time, and possessed remarkable inventive powers. He investigated the nature of urinary calculi and chalk stones. His paper on the oxalates of potash was of great service at the time as a demonstration of the law of multiple proportions. He first drew attention to the existence in the solar spectrum of what were subsequently termed the Fraunhofer lines; and he invented the reflecting goniometer and the camera lucida, and a slide rule for chemical calculations. He resembled Cavendish in temperament and mental habitudes, and, like him, was distinguished for the range and exactitude of his scientific knowledge, his habitual caution, and his cold and reserved disposition. He died in 1828.
William Hyde Wollaston.
From a painting by J. Jackson, R.A., in the possession of the Royal Society.