BIOGRAPHY OF Slit HUMPHRY DAVY. CIIAFTER SIXTH.

HAD Sir Humanity DAVY possessed no other claims to admiration than those founded upon his Voltaic discoveries, his thme could never

have perished but with the general extinction of Science and the Arts. The subjoined list, however, of his different memoirs will show, that, splendid as were his achievements in that branch of knowledge, those researches constitute but a small part of the labours for which he will receive the gratitude and homage of posterity. In our five preceding chapters, we fear we may have too far invaded the province of the scientific journalist, and dived too deeply into the recesses of Chemistry ; we shall, for the future, endeavour to observe the rule conventionally established by the writers of popular articles, who like swallows should skim a large surface with rapidity. The following is a list of the memoirs read before the Royal Society by our distinguished philosopher : they alike evince the profundity of his researches, and the versatility of his genius. •

1. An Account of some Galvanic Combinations formed by single metallic plates and fluids, anzdagous to the Galvanic Apparatus of M. Volta. Read June 18, 180L 2. An Account of some Experiments and Observations on the constituent parts of certain Astringent Vegetables, and on their operation in Tanning. February 24, 1803. 3. An Account of some Analytical Experiments on a Mineral Production from Devonshire, consisting principally of Alumina and Water. &bra. ary 28, 1805.

4. On a Method of Analysing Stones, containing a Fixed Alkali, by means of the Boracic Acid. May 16, 18115.

5. Tin: LEcTuax. On sonic Chemical Agencies of Electricity. Raid November 20, IN06.

G. THE BAKERIAN LECTURE. Ott some New Phenomena of Chemical Changes, produced by Electricity, particularly the Decomposition of the Fixed Alkalies, and the Exhibition of the New Substances which constitute their Bases ; and on the General Nature of Alkaline Bodies.

Norember 19, 1807. 7. Electro-Chemieal Researches on the Decomposition of the Earths; with Observations on the Metals °bullied front the Alkaline Earths; and on the Amalgam procured from Ammonia. Read Jane 7i0, 1808. 8. THE BARMAN LECTURE. Alt Account of sonic New Analytical Researches on the Nature of certain Bodies, particularly the Alkalies, Phosphorus, Sulphur, Carbonaceous Matter, and the Acids, hitherto undecompounded ; with some General Observations on Chemical Theory. Read Peeember 15, 18P8.

9. New Analytical Researches on the Nature of certain Bodies; being an Appendix to the Bakerian Lecture for 1808.

10, TUE BAKERIAN LECTURE FOR 1809. On some New Electro-Chemical Researches on various Objects, particularly the Metallic Bodies from the Alkalies and Earths ; and on sonic Combinations of Ilydregen. November 16.

II. Researches on the Oxy-muriatic Acid, its Nature, and Combinations; and on the Elements of M nriatic Acid ; with some Experiments on Sulphur and Phosphorus, made in the Laboratory of the Royal Institution. lusty 12, 1810.

12. Tut BAKERIAN LECTURE FOR 1810. On some of tile Combinations of Oxy-muriatic Gas and Oxygen, and on the Chemical Relations of those principles to Inflammable bodies. Norember 15.

On a Combination of Oxy-muriatie Gas and Oxygen Gas. Read February 21, 1811. *N. On seine Combinations of Phosphorus and Sulphur, and on some other subjects of Chemical Inquiry. June 18, 1812. 15. On a New Detonating Compound ; in a letter to Sir Joseph Banks. Nurcanter 5, 1812. iI3.

16. Some further Observations on a New Detonating Substance. July 1, 1813. 17. Some Experiments and Observations on the Substances produced in different Chemical Processes on Fluor Spar. Read July 8, 1813.

18. An Account of some New Experiments on the Fluorie Compounds; with some Observations on other objects of Chemical Inquiry. Read February 3, 1814.

19. Some Experiments and Observations on a New Substance which becomes a Violet-coloured Gas by Heat. Read January 20, 1814.

20. Further Experiments and Observitions on Iodine. Read June 1G, 1814. 21. Some Experiments on the Combustion of the Diamond, and other Carbonaceous Substances.

22. Some Experiments and Observations on the Colours used in Painting by the Ancients. Fehruary 23, 1815.

23. Some Experiments on a Solid Compound of Iodine and Oxygen, and on its Chemical Agencies. April 20, 1815.

21. Oil the Action of Acids upon the Salts usually called Hyper-Oxy-muriates ; and on the Gases produced from them. May 4, 1815.

25. On the " Fire Amy" of Coal Mines, and on Methods of Lighting the Mine; so as to prevent explosion. November 19, 1815.

26. An Account of an Invention for giving Light in Explosive Mixtures of " Fire Damp " in Coal Mines, by consuming the Fire Damp. January 11, 1816.

27. Further Experiments on the Combustion of Explosive Mixtures, confined by Wire Gauze, with some Observations on Flame. January 25, 1816. 08, Some ReF;earches on Elaine. January 16, 1817.

29. Some New Experiments rind Observations on the Combustion of Gaseous Mixtores, with an Account of a Method of preserving a continued Light in mixtures of Inflammable Gases and Air, without Flame. Read January 23, 1817.

30. On the Fallacy of Experiments in which Water is said to have been formed by the Decomposition of Chlorine. February 12, 1818.

31. NCW Experiments on souse of the Combinations of Phosphorus. April 9, 1818.

32. Some Observations on the Formation of Mists in particular situation s Read February 20, 1819.

33. On the Magnetic Phenomena produced by Electricity. Norember 16, 1820. 3.1. some Observations and Experiments on the Papyri, found in the Ruins of Herculaneum. March 15, 1821.

35. Further Researches on the Magnetic Phenomena produced by Electricity ; with some New Experiments on the properties of Electrided.Bodies, hi their relations to Conducting Powers, and Temperature. July 5, 1921.

36. On the Electrical Phetlomuna exhibited in Vacuo. December 20, 1521.

37. On the State of kVater and Aiiriform Matter in Cavities found in certain Crystals. .111lie 13, 1522. 35. On a New Phenomenon of Electro-magnetism. March 6, 1823.

39. On the Application of Liquids formed by the Condensation of Gases, as :Mechanical Agents. 17, 1523.

40. On the Changes of Volume produced in Gases in different states of Density by Heat. /thy 1, 1823.

41. On the Corrosion of Copper Sheathing. by Sea Water ; and on Methods of preventing this effect, and on their Application to Ships of War, and other Ships. Read january 24, 1824.

42. Additional Experiments and Observations on the application of Electrical Combhfations to the Preservation of the Copper Sheathing of Ships, and to other purposes. June 17, 1824. 43. Further Researches on the Preservation of Metals by Electro-Chemical means. June 9, 1825.

4-1. TUE BAKERIAN LECTURE FOR 1826. On the Relation of Electrical and Chemical Changes. June 3, 1826. 45.40n the Phenomena of Volcanoes. March 20; 1828.

46. Account of some Experiments on the Torpedo. November 20, 1828.

If we except the series of papers developing the laws of electro-chemical action, upon the paramount importance of which there never has existed but one opinion, chemists may, perhaps, differ in their esti

mate of the comparative value of his other memoirs. Those who have not made philosophy their study, and the business of their lives, are too apt, and very naturally, to estimate the merit of a discovery by the ex

tent and importance of its immediate applications for the benefit of society ; but a little reflection will convince the candid reasoner that such a standard is wholly deceptive. A very insignificant discovery, for instance, may be instantly brought to bear for the improvement of some process in the arts, and every superficial observer is capable of

appreciating its ; while a laborious investigation into abstruse phenomena, however successfully it may have cleared away error, unless it is followed by some obvious and useful application, will never excite general eclat. What eulogies have been passed upon WATT for his improvements in the Steam-Engine ! but how very few are aware that Dr. BLACK is entitled to a much larger share of honour, for discovering the laws of Latent Heat, upon which such improvements were entirely founded ! So, in the case of Sir HUMPHRY DAVY, those memoirs which, in a philosophical point of view, deserve the highest praise, appear to have excited the least general admiration. We confess that we have felt something very like humiliation, on seeing his name so exclusively spoken of as the " inventor of the Safety Lamp ;" while in every engraving, Davy and his wire-gauze apparatus appear as inseparable as the watchman and his lantern. We do not by any means intend to depreciate the high utility of this invention ; but we consider that DAVY'S claims rest upon much higher scientific pretensions. If we were called upon for our judgment upon this occasion, we confess that we should consider his several memoirs upon the nature of Oxy-muriatic Acid, as ranking next in importance and scientific utility to his Voltaic discoveries : and we feel confident that such a judgment must be confirmed by those who are capable of understanding how great a mass of error was thus exploded, what important analogies were suggested, and what generalizations established. Had not the general opinion of the simple nature of Muriatic Acid been overturned, time acidifying power of Hydrogen in certain combinations would not have been speedily acknowledged ; nor would the relations of this element to the various compounds of Iodine, Cyanogen, &c. been readily understood ; indeed, it might be easily shown, that one of the greatest revolutions to which chemistry has been subjected, may be referred to the new view taken by Sir RUMPHRY upon this occasion.

After these papers, it may be questioned whether his discoveries relative to the nature of Flame may not be received as the most remark able. The invention and theory of the Safety Lamp were the results. But feeling the utter impossibility of doing justice to such questions,

without entering into details wholly inconsistent with the nature of the publication for which we are writing, we shall close our sketch with a popular view of the Safety Lamp, which, as an instrument for protecting. human life, must ever\be viewed as one of the blessings conferred upon mankind by the immortal genius of its inventor. It was in attempting to measure the expansion occasioned by the combustion of a mixture of fire-damp ( Carburetted Hydrogen) and common air, that Sir HUMPHRY DAVY discovered a fact, which, by an ingenious and happy train of reasoning, led to the invention of his lamp.

He ascertained that an explosive mixture could not be kindled in a glass tube so narrow as .1 of an inch in diameter ; and that when two separate reservoirs of an explosive mixture were connected by a metallic tube, of an inch diameter, and 11 inch in length, and one of the portions of the gas was set on fire, the explosion did not extend th the other. Another equally curious fact was discovered during this investigation,—namely, that a mixture of fire=danireand air, in explo sive proportions, was deprived of its power of exploding,, by the addition of about 4 its bulk of carbonic acid, or nitrogeif gas ; a fact which at once suggested the possibility of constructing a lamp, in which the flame, by being supplied with only a limited quantity of air, might produce carbonic acid and nitrogen, in such proportions as to destroy the combustibility of explosive mixtures, and which might also, by the nature of its apertures for giving admittance and exit to the air, be rendered incapable of spreading combustion to the surrounding at mosphere, supposing it to be an inflammable one. This object was accomplished by the use of air-tight lanterns, supplied with air through tubes, or canals, of small diameter, or through apertures covered with wire gauze below the flame, and having a chimney at the upper part on a similar system for carrying off the foul air. The apparatus was afterwards simplified by covering or surrounding the flame of a lamp

or candle with a cylindrical wire sieve, having at least 623 apertures in a square inch. Within this cylinder, when the fire-damp encompassing, it is to the air as I to 12, the flame of the wick is seen surrounded by the feeble blue flame of the gas. When the proportion is as 1 to 5, 6, or 7, the cylinder is filled with the flame of the fire-damp; and though the exterior air is explosive, it is not kindled by it. Thus is the miner now enabled to penetrate into the deepest recesses, fearless of the fire dwmon who had, previous to this invention, brought so many of his unhappy brethren to a premature end : the enemy is no sooner encountered than he is defeated, and may be seen harmlessly fluttering in the iron cage. There is something very like magic in all this ; and the author of such an invention a century ago, would have stood a fair chance of being burnt for witchcraft : but we have to relate another property in this lamp that partakes still more of the marvellous. If a small coil of platinum wire be hung above the wick of the lamp within the wire gauze cylinder, the following effects will take place. After the explosive mixture has burnt for some time, it will expire; together with the lamp, and the miner would be left in impenetrable darkness ; but at this embarrassing moment, the little coil of platinum will begin to glow with a light sufficiently bright to guide him into a purer atmosphere, when the heat thus produced will be sufficient to rekindle the lamp ! This phenomenon is to be explained upon a principle discovered during the progress of the inquiry into the nature of flame, which Sir HUMPHRY proved to require a high temperature for its maintenance. When, therefore, the combustion of the fire-damp is reduced to so low a temperature as to be inadequate to that ignition of gaseous matter which constitutes flame, it may still excite a temperature sufficient to render platinum wire luminous. Various applications of this principle have been made for the construction of philosophical trifles, and which any of our readers may very easily repeat. For instance, an ignition of platinum wire, giving light enough to read by, may be supported for many hours, by surrounding the flame of a common spirit lamp with small coils of the wire, not exceeding 1.4 of an inch in diameter. Twelve coils of this wire, twisted spirally round the tube of a tobacco-pipe, or round anything that will render the coils about of an inch in diameter, are to surround the wick. When the lamp, after being lighted for a few moments, is blown out, the platinum will glow, and continue in that state as long as there is a supply of spirit of wine. The spirit dining this slow combustion is converted into vinegar ; and hence an aromatic fumigating lamp, for a sick chamber, has been lately advertised for sale, and which is no other than the contrivance above described ; and it is evident that if the spirit be impregnated with fragrant principles, an aromatic vinegar will be diffused in fumes through the apartment. But to return from this digression to the Safety Lamp: it is now generally admitted that its protecting powers depend upon the cooling agency of the wire gauze, exerted on the portion of gas burning within the cylinder.

An investigation of the other researches of Sir HUMPHRY DAVY would occupy many snore chapters ; indeed, to do full justice to his labours, an author might supply materials for at least an octavo volume ; and such is the popular nature of his discoveries, and the connexion which subsists between them and the ordinary objects of life, that the interest such a work must excite would not be confined within the small circle of philosophers, but it would be read with avidity by the general mass of the intelligent public. The author of the Sketches which have appeared in this paper, has heard that the extent of DAVY'S labours, briefly, and in every respect imperfectly as they have been announct d, have not failed to excite general attention. Few philosophers ha,ve done so much, and are known so little.His name, it is true, is as familiar as that of the Prime Minister ; but if wc except the Fellows of the Royal Society, and a few who are addicted to science, that name is rarely mentioned in any society, without our hearing it asked by some one present-" What has Sir HUMPHRY done?" We happen to know that Mr. MURRAY has taken measures to enlighten the public upon this question.