Oldalképek
PDF
ePub

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. 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 20001., at a public dinner at Newcastle, October 11. 1817.

In 1813, Sir Humphry was elected a corresponding member of the Institute of France, and vice-president of the Royal Institution. He was created a Baronet, October 20. 1818. In 1820, he was elected a foreign associate of the Royal Academy of Sciences at Paris, in the room of his countryman Watt; and in the course of a few years, most of the learned bodies in Europe enrolled him among their members.

Many pages might be occupied with the interesting details of Sir Humphry Davy's travels in different parts of Europe for scientific purposes, particularly to investigate the causes of volcanic phenomena, to instruct the miners of the coal districts in the application of his safety-lamp, to examine the state of the Herculaneum manuscripts, and to illustrate the remains of the chemical arts of the ancients. He analysed the colours used in painting by the ancient Greek and Roman artists. His experiments were chiefly made on the paintings in the baths of Titus, the ruins called the baths of Livia, in the remains of other palaces and baths of ancient Rome, and in the ruins of Pompeii. By the kindness of his friend Canova, who was charged with the care of the works connected with ancient art in Rome, he was enabled to select, with his own hands, specimens of the different pigments that had been found in vases discovered in the excavations which had been lately made beneath the ruins of the palace of Titus, and to compare them with the colours fixed on the walls, or detached in fragments of stucco. The results of all these researches were published in the Transactions of the Royal Society for 1815, and are extremely interesting. The concluding observations, in which he impresses the superior importance of permanency to brilliancy, in the colours used in painting, are especially worthy the attention of artists. On his examination of the Herculaneum manuscripts at Naples, in 1818-19, he was of opinion they had not been acted upon by fire, so as to be completely carbonised, but that their leaves were cemented together by a substance formed during the fermentation and chemical change of ages. He invented a composition for the solution of this substance, but he could not discover more than 100 out of 1265 manuscripts, which presented any probability of success.

Sir Humphry returned to England in 1820, and in the same year his respected friend, Sir Joseph Banks, President of the Royal Society, died. Several discussions took place respecting a proper successor, when individuals of high and even very exalted rank were named as candidates. But science, very properly in this case, superseded rank. Amongst the philosophers whose labours had enriched the transactions of the Royal Society, two were most generally adverted to, Sir Humphry Davy and Dr. Wollaston; but Dr. Wollaston, who had received from the council of the Society the unanimous compliment of being placed in the chair till the election by the body in November, declined any competition with his friend Sir Humphry Davy. Sir Humphry retained his seat as President till the year 1827, when, in consequence of procrastinated ill health, in great measure brought on by injuries occasioned to his constitution by scientific experiments, he was induced, by medical advice, to retire to the Continent. He accordingly resigned his seat as President of the Royal Society, the chair being filled, pro temp, by Davies Gilbert, Esq. who at the anniversary meeting, November 30. 1827, - was unanimously elected President.

During his retirement on the Continent, Sir Humphry continued to communicate the results of his labours to the Royal Society ; and at the anniversary meeting of the year 1827, one of the royal medals was awarded to him for a series of brilliant discoveries developing the relation between electricity and chemistry, and to which we have already alluded. Upon this interesting occasion, Mr. Davies Gilbert spoke as follows : — "It is with feelings the most gratifying to myself, that I now approach to the award of a royal medal to Sir Humphry Davy; having witnessed the whole progress of his advancement in science and in reputation, from his first attempts in his native town, to vary some of Dr. Priestley's experiments on the extrication of oxygen from marine vegetables, to the point of eminence which we all know him to have reached.

"It is not necessary for me to do more than to advert to his discovery of nitrous oxide; to his investigation of the action of light on gases; on the nature of heat; to his successful discrimination of proximate vegetable elements; nor to his most scientific, ingenious, and useful invention, the safetylamp,—an invention reasoned out from its principles with all the accuracy and precision of mathematical deduction.

"The particular series of discoveries for which the Royal medal has been awarded are those which develope the relation between electricity and chemistry.

"Soon after Sir Humphry Davy had been seated at the Royal Institution by an invitation from Count Rumford, an invitation founded on his first production,—a paper on the nature of heat, —our late President began his experiments and investigations on electric chemistry: a most powerful Voltaic apparatus was fortunately placed at his disposal; and in his hands electric chemistry soon became the most important branch of practical science: important from its immediate energies and powers; but much more so from the general laws of nature, which it has laid open to our view.

"A new acidifying principle, or supporter of combustion, was discovered, possessing the same negative electric properties as oxygen. Muriatic acid disclosed its real composition. The oxymuriates were transferred to their proper class. The alkalies were reduced into metals; and the earths were proved to be similar oxides. But in the progress of these experiments a discovery was made, surpassing all the wonders attributed

14

to alchemy. Three basins were arranged in a straight line, each containing water, and to the middle basin some neutral salt was added. The three were connected by moistened siphons of asbestos: the opposite piles of a Voltaic battery were then applied to the extreme vessels; and in a short time the neutral salt disappeared from the middle basin, and its constituent parts were found separated j the acid attracted to the positive pile of the battery, the alkali to the negative. This astonishing result, followed up by other experiments, led to the conclusion that chemical energies may be increased, diminished, or even inverted, by the superinduction of electric powers homogeneous with or dissimilar from their own. This metastasis in the hands of physiological enquirers promises to conduct them to discoveries of the utmost importance in the functions of life. I flatter myself that it is now actually in such hands.

"The principle of varying or modifying chemical energies by those of electricity, has been applied by the invention, in a manner the most philosophical, and on a scale the most extensive.

"The copper sheathing of ships and vessels had been found to corrode in the short period of a single voyage, being converted into an oxide through the medium of some acid, or at least of a decompounded substance, occupying the negative extremity of the electric scale. The copper must, therefore, be positive in respect to the body decomposed or attracted. A reference was made by the government to the Royal Society, with the hope of discovering some remedy for this most serious evil. Grounded on a perfect knowledge of chemical and of electric powers, it immediately occurred to the illustrious discoverer of their relations one to the other, that if a substance more positive than copper, and in contact with it, could be exposed to the corroding action, that the copper would, by induction, be rendered less positive, and, therefore, indisposed to combine with any other negative body.

"Experiments the most satisfactory were then made on a small scale; and in consequence of their success, plates of zinc, and afterwards of iron, were applied to ships' bows; and the copper has been fully and completely protected. The theory and the experiments have been confirmed in the most ample manner. A defect has, indeed, occurred in practice from the over-success of protection. The induction of negative powers to the copper has gone too far; they have caused it to act on the compounds in an opposite direction, by attracting to itself the earths and alkalies, thus affording attachments to the marine vegetables which the copper was intended to prevent. This appears to me, however, susceptible of a cure. I am sufficiently advanced in years to remember the American revolution war. Ships were then first sheathed with copper: they were preserved clean from weeds, nor was the copper corroded; but the ships were fastened together by iron bolts, and these, to the utter astonishment of every one, decayed; and the ships became unable to sustain the ordinary straining in gales of wind. For some time the effect could not be traced to its cause, for galvanism was then unknown; but at last bolts made of bronze were substituted for those of iron, and immediately the copper failed. When the theory has, therefore, been modified by experience on the principle of these empiric trials during the American war, I cannot hesitate in predicting complete practical success, with full glory to the illustrious individual who deduced the practice from theory, and with ample advantage to all those who may then bring the practice into beneficial use.

"Sir Humphry Davy having last year communicated a paper to the Society in continuation of his former inductions and generalisation on chemical and electric energies, there cannot be a doubt but that the only obstacle against his then receiving a royal medal, on the first occasion that the Society had it to bestow, was his occupying this chair. That obstacle, unhappily for science, no longer exists; and the Royal Society take this earliest opportunity of testifying their high estimation of these talents and of these labours which all Europe admires. We trust and hope, although our late President has been induced by medical advice to retire from

« ElőzőTovább »