Some of the results of those experiments were afterwards disputed, and various claims were made to the originality of the invention by which they had been conducted; but it is somewhat remarkable that while these claims and disputes continue to be agitated, the author of the work now before us is the only person who has appropriated the instrument itself to any purpose of public utility. During four years which have elapsed since he commenced his experiments with this blow-pipe, he has persevered in exhibiting to the members of the university, before whom he delivers his public lectures, a repetition of those experiments; confirming the truth of them by daily appeals to their testimony, as to the facts which they substantiate. The object of the present publication is, therefore, to shew the utility and safety of the apparatus employed; to point out the progressive steps by which it has been brought to its present state of improvement; the share which the author himself had in the invention; and the proofs which the instrument has afforded of analogy in its operations to the nature of volcanoes; that is to say, in its power of fusion; the means whereby this fusion is accomplished; the result of the combustion of the mixed gases, forming water; and the detonations and explosions to which the same com. pressed gaseous mixture is liable.-The subject is curious, and the author shall speak for himself. The present observations relate to the Gas Blow-pipe as used for burning a compressed mixture of hydrogen and oxygen gases, when propelled from a common reservoir. The first usage of these gases. in a state of mixture, was believed to have been made by an unknown native of Germany; who employed for this purpose a bladder to which a capillary tube was affixed. The author received this information, upon report, after he began to write the account of his own experiments; but no one has since laid claim to the experiment, nor does he now know whether there be any truth in the rumour. He has been, however, the more anxious to repeat it; because upon the truth of it depend all pretentions to priority of invention. Dr. Thomas Thomson, now professor of chemistry at Glasgow, made experiments with the mixed gases, at Edinburgh, seventeen years ago; but was induced to abandon the undertaking, owing to the accidents which happened to his apparatus. With respect to the application of hydrogen and oxygen gases to aid the operations of the blow-pipe, when propelled from different reservoirs through different apertures, by means of hydrostatic or other pressure, the contrivance is as old as the time of Lavoisier. The American chemists lay claim to it, as their invention, in consequence of experiments made, in 1802, by Mr. Robert Hare, junior, professor of Natural Philosophy in Philadelphia; of which an account appeared in Dr. Bruce's Mineralogical Journal*, *Vol. I. No. 2. p. 97. (Note.) and and also in the Annales de Chimie.* Much about the same time, Dr. Thomson also carried on a series of experiments in the same way; ↑ and we have witnessed similar experiments, for at least a dozen years, during the chemical lectures delivered in the University of Cambridge. The combustion of the diamond was always thus exhibited and in America this plan is still pursued; that is to say, the two gases are propelled from different reservoirs, and through different apertures. But the intensity of the heat is incomparably greater when the gases, after compression, are propelled and burned in a mixed state; because the due proportion necessary for forming water is then constantly and equally maintained whereas an excess, either on the side of the hydrogen or of the oxygen, not only tends to diminish the temperature, but, if it be much increased on the side of the oxygen, infallibly extinguishes the flame. : As this method of aiding the operations of the blow pipe differs, in this essential particular, from every other hitherto employed, it is that to which (with all the improvements since made for insuring the safety of the operator) the name of the Gas Blow-pipe is now applied, and whose history it is the author's present purpose to relate. And this induces a second part of the inquiry; namely, what first suggested the propriety of mixing the two gases in the relative proportion for forming water? because, upon the observance of this proportion the intensity of the heat mainly depends. This circumstance was briefly stated in the first account which the author published of his experiments with the gas blow-pipe; but the phænomena upon which it was founded, highly interesting as they are, do not seem to have met with that attention from scientific men to which they are entitled; probably owing to the very short time usually bestowed by scientific travellers amidst the scenes where such phænomena are fearfully displayed. The author alludes to the phænomena attendant upon volcanoes; the discomposition of water by volcanic fire; the compression to which the gaseous result is liable; its subsequent combustion; the power of fusion it exhibits; and, lastly, the horrible explosions which take place, whenever the whole of the compressed gas is exposed to combustion. If this happen, as it is well known, whole mountains are blown into the air by the tremendous violence of the explosion, which is heard to the distance of many leagues; and the eruption ceases. But the minor explosions, or detonations, taking place at the mouths of narrow apertures in a volcano whence liquid rocks are ejected in the form of lava, are such as to resemble the loudest artillery In these cases, a partial explosion of the gaseous mixture takes place; exactly corresponding with the detonations which, upon a small scale, are heard at the orifice of the jet of the gas blow-pipe ; and bearing about the same comparison to the explosion of the gas reservoir, which the detonations at the mouth of a stream of lava do to the explosion of all the pent gas within the volcano. Vesuvius, see tom. xlv. p. 113. Mémoire sur l'Usage du Chalumeau, et les Moyens de l'alimenter d'Air,' &c. This is also stated in the Letter above mentioned, perhaps, perhaps, better than any other volcano, may serve to illustrate what is here advanced because it is better adapted for examination than Etna, or any other volcano where the crater is remote from the syringes or jets through which the lava is propelled. This mountain, as to its chemical nature, is, in all respects, a vast gas blow-pipe; corresponding, in all its phænomena, with the appearances and effects, the explosions and detonations, the heat and the light, exhibited by the apparatus which bears this name; and differing from it only as the mighty operations of nature in the universe differ from the puny imitations of the chemist in his laboratory. During twelve years that the author has delivered public lectures, in the University of Cambridge, as it is well known to persons who have attended those lectures, he has constantly thus explained the nature and effects of volcanic eruptions. Without the agency of water and its decomposition, these eruptions do not take place. Before any great eruption of Vesuvius, not only does the water disappear in all the wells of Naples, Portici, Resina, and other towns at the foot of the mountain, but even the sea retires; and marine animals, abandoned by their native element, expire upon the shore.' Dr. Clarke then proceeds to verify these observations by a reference to the phænomena which accompanied the rising of the Monte Nuovo, out of the Lucrine lake, near Naples, and to others of which he was an eye-witness upon Mount Vesuvius; and afterwards relates the inferences deduced from those appearances as they were rendered applicable to the gas blow-pipe. Consequently, to imitate the power of fusion exhibited by a volcano, nothing more was necessary than to burn the gaseous constituents of water under similar circumstances; but here was the difficulty. Every clap of thunder in the atmosphere is sufficient to prove what the consequences are, where the gaseous constituents of water, when in a mixed state, become ignited, even by an electric spark: and who would venture to communicate flame to such a mixture, under compression, for purposes of experiment? The experiments which took place under Lavoisier at Paris and all over Europe, for the composition of water were an approximation towards it; because these experiments first proved that the gaseous constituents of water might be used to aid the operatious of the blow-pipe. It was then, in fact, first made known, that the two gases, when burned separately, and propelled from different reservoirs, through different apertures,by hydrostatic pressure,towards one point (which was the method afterwards pursued by Professor Hare in America), exhibited a degree of temperature capable of effecting THE COMBUSTION OF THE DIAMOND! Therefore, if it be requisite to trace the invention of the gas blow-pipe to the first principles which led to the whole of the contrivance, it is to these discoveries of Lavoisier There is no other way in which any idea can be given of the intense light beaming from the source of a stream of perfectly liquid lava, than by attending to the fusion of the most refractory substances before the gas blow-pipe, which exhibits an emanation of the same kind of light, comparatively, as the light of a star, to that of the sun. that that reference should be made. As soon as the invention of Mr. Brook's blow-pipe offered an easy method of compressing and propelling one of the gaseous constituents of water, while the other might be afforded by the combustion of a spirit-lamp, the author, of course, as he has before acknowledged, availed himself of this apparatus ;* but finding, as he before said, that the heat was not sufficient for his purpose, "because the hydrogen was not afforded in its due proportion," he was directed, by the maker of the blow-pipe, to compress the mixed gases, and burn them, upon the principle of gas illumination, when pro pelled through a capillary tube. As to the relative proportion between the two gases, after all that he now has stated, and during twelve years has constantly repeated, upon the subject of volcanoes, at his public lectures before the University of Cambridge,-is it necessary to ask, whether he would hesitate to mix them in the proportion for forming WATER? That he did not hesitate, is evident; because in the very beginning of the earliest account which he published of his experiments with the gas blow-pipe, and in the very first words of it, he mentions "water as the combustible for increasing the action of fire ;”—and in a page almost immediately following,§ he states the relative proportion between the two gases which he had adopted; namely," two parts, by bulk, of hydrogen, and one part of oxygen." If, in any publication anterior to the article here cited, it can be made to appear that the same proportion had been adopted by any other person, he forgoes, of course, all claim to this part of the improvement in the mode of using the gas blow-pipe." The remaining pages relate to the new chemical facts which the use of this blow-pipe has made known. Among the more remarkable may be mentioned the pseudo-metallic lustre exhibited by si-, lica, and by other substances once considered as refractory bodies, when their fusion has been accomplished in a charcoal crucible. We have seen rock crystal, which, after being thus melted, appears like a globule of the purest mercury; and it retains its high metallic lustre unaltered by exposure to atmospheric air. It had fallen, while in a state of fusion, upon a deal board, into which it consequently became imbedded, and when taken out was found to have this remarkable metallic lustre. The same appearance is exhibited by pure crystallized alumina under similar circumstance, as in the instances of the sapphire and the ruby. Does not this admit of an obvious explanation? We would propose it as a quære for our chemical readers, whether charcoal coming into contact with metallic oxides when in a state of fusion, and at a temperature so exalted, may not, from its powerful affinity of oxygen, so far revive the metals of the earth as to exhibit them in a minimum of oxidation, and with metallic lustre, in the form of the thin superficies Journal of the Royal Institution, III. 105. 60 + Ibid. Ibid. which which then invests those bodies. The fusion of wood-tin, and the perfect metallic lustre it afterwards exhibits, even when cut by a file, although still remaining in the state of an oxide; the combustion of platinum; the melting of rubies, sapphires, and emeralds, so as to cause them to run together into one mass; the revival of certain metals from their oxides; and above all, the revival of a perfectly metallic appearance from barytes, which again becomes barytic earth upon simple exposure to the action of atmospheric air, are among the other new chemical results which the use of the gas blow-pipe has enabled the author to obtain. It is now above forty years since the first experiments with oxygen gas, in aid of fusion, were made by the celebrated Achard, as may be seen by reference to the Proceedings of the Academy of Sciences, at Berlin, for the year 1779.* The observations of Lavoisier, upon the same subject, appeared in the Transactions of the Royal Academy of Sciences, at Paris, three years afterwards.t Achard, by propelling a stream of what he called, after Priestley, dephlogisticated air, upon the flame of a lamp, succeeded in melting grains of platinum, and other refractory bodies. These experiments were followed by Ehrmann, of Strasbourg, who, in 1785, published a work, which was translated by Fontallard, and entitled Essai d'un Art de Fusion, a l'aide de l'Air du Feu, ou Air Vital. By an extract made from the Records of the Academy at Paris, signed by the Marquis of Condorcet upon the 23d of June, 1786, it appears that Lavoisier, Berthollet and Fourcroy had been appointed by the Academy de lui rendre compte de l'ouvrage de M. Ehrmann traduit par M. de Fontallard; upon which occasion it was urged that Ehrmann's experiments were unknown to Lavoisier, although in their results they agreed so strikingly with those which the French chemist had obtained. In these experiments a degree of heat had been excited nearly equal to that which is developed by burning the gaseous constituents of water. Lavoisier failed, however, in his endeavour to accomplish the fusion of rock crystal ;t and in numerous experiments made upon this substance in 1772, with the great burning glass of Ischirnhausen, it had resisted the most exalted temperature to which it was exposed. The same thing happened See also the Chemical Memoirs of François Charles Achard, vol. i. page 134. Berlin, 1784. Mémoires par M. Lavoisier sur l'Action du Feu animé par l'Air vital, sur les Substances Minérales les plus réfractaires, publiés dans les Mémoires de l'Académie Royale des Sciences. 'Quoi ue l'activité du feu fût très-grande, il n'a pas fondu pendant l'espace de 2 minutes 30 secondes qu'a duré l'expérience.'-Mémoire de M. Lavoisier, p. 243. Strasbourg, 1787. |