278 WORKMEN AND HEROES metaphysics, and physiology ; before he was nineteen he began to study chem- istry, and in four months proposed a new hypothesis on heat and light, to which he won over the experienced Dr. Beddoes. With his associate, Greg- ory Watt (son of the celebrated James Watt) he collected specimens of rocks and minerals. He made considerable progress in medicine ; he experimented zealously, especially on the effects of the gases in respiration ; at the age of twenty-one he had breathed nitrous oxide, and nearly lost his life from breath- ing carburetted hydrogen. Next year he commenced the galvanic experiments which led to some of his greatest discoveries. In 1802 he began his brilliant scientific career at the Royal Institution, where he remained till 181 2; here he constructed his great voltaic battery of 2,000 double plates of copper and zinc, and commenced the mineralogical collection now in the Museum. His lect- ures were often attended by one thousand persons : his youth, his simplicity, his natural eloquence, his chemical knowledge, his happy illustrations and well-con- ducted experiments, and the auspicious state of science, insured Davy great and instant success. The enthusiastic admiration with which he was hailed can hardly be imagined now. Not only men of the highest rank men of science, men of letters, and men of trade but women of fashion and blue-stockings, old and young, pressed into the theatre of the Institution to cover him with applause. His greatest labors were his discovery of the decomposition of the fixed alkalies, and the re- establishment of the simple nature of chlorine ; his other researches were the in- vestigation of astringent vegetables in connection with the art of tanning ; the analysis of rocks and minerals in connection with geology ; the comprehensive subject of agricultural chemistry ; and galvanism and electro-chemical science. He was also an early, but unsuccessful, experimenter in the photographic art. Of the lazy conservative spirit and ludicrous indolence in science, which at this time attempted to hoodwink the public, a quaint instance is recorded of a worthy professor of chemistry at Aberdeen. He had allowed some years to pass since Davy's brilliant discovery of potassium and its congeneric metals, without a word about them in his lectures. At length the learned doctor was concussed by his colleagues on the subject, and he condescended to notice it. " Both potash and soda are now said to be metallic oxides," said he ; " the oxides, in fact, of two metals, called potassium and sodium by the discoverer of them, one Davy, in London, a verra troublesome person in chemistry." Turn we, however, to the brightest event in our chemical philosopher's career. By his unrivalled series of practical discoveries, Davy acquired such a reputation for success among his countrymen, that his aid was invoked on every great oc- casion. The properties of fire-damp, or carburetted hydrogen, in coal-mines haa already been ascertained by Dr. Henry. When this gas is mingled in certain pro- portions with atmospheric air, it forms a mixture which kindles upon the contact of a lighted candle, and often explodes with tremendous violence, killing the men and horses, and projecting much of the contents of the mine through the shafts or apertures like an enormous piece of artillery. At this time, a detonation of
