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_. [Illustration: 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. [Illustration: WILLIAM HYDE WOLLASTON. From a painting by J. Jackson, R.A., in the possession of the Royal Society.]