Mr. Davy's first experiments as Professor of Chemistry in the Royal Institution, were made on the substance employed in the process of tanning, with others to which similar properties were ascribed, in consequence of the discovery made by M. Seguier, of Paris, of the peculiar vegetable matter, now called tannin. He was, during the same period, frequently occupied in experiments on galvanism.

To the agriculturist, chemistry is of the first consideration. The dependence of agriculture upon chemical causes had been previously noticed, but it was first completely demonstrated in a course of lectures before the Board of Agriculture, which Mr. Davy commenced in the year 1802, and continued for ten years. This series of lectures contained much popular and practical information, and belongs to the most useful of Mr. Davy's scientific labours; for the application of chemistry to agriculture is one of its most important results; and so rapid were the discoveries of the author, that in preparing these discourses for publication, a few years afterwards, he was under the necessity of making several alterations, to adapt them to the improved state of chemical knowledge, which his own labours had, in that short time, produced.

In 1803, he was chosen a fellow of the Royal Society, and in 1805, a member of the Royal Irish Academy. He now enjoyed the friendship of most of the distinguished literary men and philosophers of the metropolis, and enumerated among his intimate friends, Sir Joseph Banks, Cavendish, Hatchett, Wollaston, Children, Tennant, and other eminent men. At the same time he corresponded with the principal chemists of every part of Europe. In 1806, he was appointed to deliver, before the Royal Society, the Bakerian lecture, in which he displayed some very interesting new agencies of electricity, by means of the celebrated galvanic apparatus 1 Soon afterwards, he made one of the most brilliant discoveries of modern times, in the decomposition of two fixed alkalies, which, in direct refutation of the hypothesis previously adopted, were found to consist of a peculiar metallic base united with a large quantity of oxygen. These alkalies were potash and soda, and the metals thus discovered were called potassium and sodium, Mr. Davy was equally successful in the application of galvanism to the decomposition of the earths. About this time he became Secretary of the Royal Society. In 1808, Mr. Davy received a prize from the French Institute. During the greater part of 1810, he was employed on the combinations of oxymuriatic gas and oxygen; and towards the close of the same year, he delivered a course of lectures before the Dublin Society, and received from Trinity College, Dublin, the honorary degree of LL. D.

In the year 1812, Mr. Davy married his amiable lady, then Mrs. Apreece, widow of Shuckburgh Ashby Apreece, Esq. and daughter and heiress of the late Charles Kerr, of Kelso, Esq. By his union with this lady, Mr. Davy acquired not only a considerable fortune, but the inestimable treasure of an affectionate and exemplary wife, and a congenial friend and companion, capable of appreciating his character and attainments. A few days previously to his marriage, he received the honour of knighthood from his Majesty, then Prince Regent, being the first person on whom he conferred that dignity.

We now arrive at the most important result of Sir Humphry Davy's labours, viz. the invention of the SAFETY-LAMP for coal mines, which has been generally and successfully adopted throughout Europe. This invention has been the means of preserving many valuable lives, and preventing horrible mutilations, more terrible even than death; and were this Sir Humphry Davy's only invention, it would secure him an immortality in the annals of civilization and science. The general principle of this discovery may be described as follows:

"The frequency of accidents, arising from the explosion of the fire-damp, or inflammable gas of the coal mines, mixed with atmospherical air, occasioned the formation of a committee at Sunderland, for the purpose of investigating the causes of these calamities, and of endeavouring to discover and apply a preventive. Sir Humphry received an invitation, in 1815, from Dr. Gray, one of the members of the committee; in consequence of which he went to the North of England, and visiting some of the principal collieries in the neighbourhood of Newcastle, soon convinced himself that no improvement could be made in the mode of ventilation, but that the desired preventive must be sought in a new method of lighting the mines, free from danger, and which, by indicating the state of the air in the part of the mine where inflammable air was disengaged, so as to render the atmosphere explosive, should oblige the miners to retire till the workings were properly cleared. The common means then employed for lighting the dangerous part of the mines consisted of a steel wheel revolving in contact with flint, and affording a succession of sparks: but this apparatus always required a person to work it, and was not entirely free from danger. The fire-damp was known to be light carburetted hydrogen gas; but its relations to combustion had not been examined. It is chiefly produced from what are called blowers or fissures in the broken strata, near dykes. Sir Humphry made various experiments on its combustibility and explosive nature; and discovered, that the fire-damp requires a very strong heat for its inflammation; that azote and carbonic acid, even in very small proportions, diminished the velocity of the inflammation; that mixtures of the gas would not explode in metallic canals or troughs, where their diameter was less than one-seventh of an inch, and their depth considerable in proportion to their diameter; and that explosions could not be made to pass through such canals, or through very fine wire sieves, or wire gauze. The consideration of these facts led Sir Humphry to adopt a lamp, in which the flame, by being supplied with only a limited quantity of air should produce such a quantity of azote and carbonic acid as to prevent the explosion of the fire-damp, and which, by the nature of its apertures for giving admittance and egress to the air, should be rendered incapable of communicating any explosion to the external air. These requisites were found to be afforded by air-tight lanterns, of various constructions, supplied with air from tubes or canals of small diameter, or from apertures covered with wire-gauze, placed below the flame, through which explosions cannot be communicated; and having a chimney at the upper part, for carrying off the foul air. Sir Humphry soon afterwards found that a constant flame might be kept up from the explosive mixture issuing from the apertures of a wire-gauze sieve. He introduced a very small lamp in a cylinder, made of wire-gauze, having six thousand four hundred apertures in the square inch. He closed all apertures except those of the gauze, and introduced the lamp, burning brightly within the cylinder, into a large jar, containing several quarts of the most explosive mixture of gas from the distillation of coal and air; the flame of the wick immediately disappeared, or rather was lost, for the whole of the interior of the cylinder became filled with a feeble but steady flame of a green colour, which burnt for some minutes, till it had entirely destroyed the explosive power of the atmosphere. This discovery led to a most important improvement in the lamp, divested the fire-damp of all its terrors, and applied its powers, formerly so destructive, to the production of a useful light. Some minor improvements, originating in Sir Humphry's researches into the nature of flame, were afterwards effected. Experiments of the most satisfactory nature were speedily made, and the invention was soon generally adopted. Some attempts were made to dispute the honour of this discovery with its author, but his claims were confirmed by the investigations of the first philosophers of the age." 2—The coal owners of the Tyne and Wear evinced their sense of the benefits resulting from this invention, by presenting Sir Humphry with a handsome service of plate worth nearly two thousand pounds, at a public dinner at Newcastle, October 11, 1817.

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