We have passed over his investigation of boracic acid, ammonium nitrate, and other compounds; we can merely mention in passing his later studies of the diamond and other forms of carbon, of the chemical constituents of the pigments used by the ancients, his investigation of the torpedo fish, and his anticipation of the arc light.
It seems fitting that Sir Humphry Davy should be popularly remembered for his invention of the miner's safety-lamp. At the beginning of the nineteenth century the development of the iron industry, the increasing use of the steam engine and of machinery in general led to great activity and enterprise in the working of the coal mines. Colliery explosions of fire-damp (marsh gas) became alarmingly frequent, especially in the north of England. The mine-owners in some cases sought to suppress the news of fatalities. A society, however, was formed to protect the miners from injury through gas explosions, and Davy was asked for advice. On his return from the Continent in 1815 he applied himself energetically to the matter. He visited the mines and analyzed the gas. He found that fire-damp explodes only at high temperature, and that the flame of this explosive mixture will not pass through small apertures. A miner's lamp was therefore constructed with wire gauze about the flame to admit air for combustion. The fire-damp entering the gauze burned quietly inside, but could not carry a high enough temperature through the gauze to explode the large quantity outside. To one of the members of the philanthropic society which had appealed to him Davy wrote: "I have never received so much pleasure from the result of any of my chemical labours; for I trust the cause of humanity will gain something by it."
Davy was elected President of the Royal Society in 1820, and retained that dignity till he felt compelled by ill health to relinquish it in 1827. "It was his wish," says his brother, "to have seen the Royal Society an efficient establishment for all the great practical purposes of science, similar to the college contemplated by Lord Bacon, and sketched in his _New Atlantis_; having subordinate to it the Royal Observatory at Greenwich for astronomy; the British Museum, for natural history, in its most extensive acceptation."