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Chemical Apparatus.

ing and Productive Cascade Analysis of Scientific Journals.

nals of Philosophy for July ib.

Dictionary of Chemistry '.'...' 278

To make Ice in the midst of Summer 279

Queries ib.

Extraordinary Engine for propelling

Vessels.... 280

Explosive Engine ,,,,,,,,,,, ib.

CONTENTS.
The Absorb- On Purifying the Air of Apartments 281

Chemistry as a Science. Art. XVII.

Bismuth. Mercury 283

Sound has no Velocity 285

More Poisons 287

Perkius outdone, or new Inventions ib.

Mr. Tait's Invention disputed. 288

Chemical Society ib.

To make Fire from Water ,,, ib.

T

CHEMICAL APPARATUS.

THE ABSORBING AND PRODUCTIVE

CASCADE.

Description of the Plate.

This is an apparatus invented and employed by Mr. Clement, a celebrated French chemist of the present day, to promote the absorption or solution of gases. It is known that this takes place in proportion to the pressure on the absorbingliquid, the extent of surface exposed to the absorbingaction,and to the length of time in which it is exposed. If the pressure, however, is very great, the vessels are apt to burst, and therefore, in general, the object chemists have had in view has been to strengthen the influence of the two other principles we have just mentioned. Mr. Clement employs the following means:—A B is a long cylinder full of a great number of small glass or porcelain balls, about one-third of an inch in diameter. This cylinder is fixed in another of a much greater diameter, in which a hole, C, is made corresponding to the lower extremity of A B, and with which two small tubes, D E, communicate, one being intended to introduce the gas, the other to empty the liquid. From a reservoir, F, a stream of water flows by means of the tube, G, which is supplied with a stopcock, so that this stream may be regulated at pleasure. The water in its descent is detained by all the little balls, which it wets successively, and is a considerable time before it reaches the bottom; on the other hand, as the gas arises it occupies all the empty space, is much divided and subdivided, and, as it also is detained in its progress npwards, the time it is in contact with the water is very considerable. The author of this invention supposes, that it is more than three hundred times more efficacious in promoting the absorption of a gas than the ordinary apparatus. This he calls the absorbing cascade, and to it he adapts another apparatus, which he calls the productive cascade. It is intended to produce gas for a

considerable period of time, and in a more convenient and less expensive manner than by the ordinary methods. Thus for example: to prepare chlorine, a large vessel, H, provided with four mouths or holes, isfilled with the oxide of manganese broken into large pieces; the mouth, I, is connected with a leaden vessel, K, containing com? mon salt and sulphuric acid. .By the tube, L, a small stream is made to flow from the reservoir, M, which gradually moistens the whole surface of the pieces of manganese, and permits the muriatic acid gas to attack and dissolve it very easily. The chlorine which is produced passes by the tube, N, into the absorbing cascade, while the muriate of manganese is carried off as it forms by the water through the tube, O, into the reservoir, P. By using this apparatus there is no occasion to reduce the manganese to powder, and a much larger quantity may be operated on at the same time, without the operator being under the necessity of frequently renewing the charge of materials and dismounting his apparatus. We should suppose that many of our readers who have chemical operations to perform, will find Mr. Clement's a very useful method.

ANALYSIS OF SCIENTIFIC JOURNALS.

ANNALS OF PHILOSOPHY FOR JULY.

Great complaints have lately been made of the inefficiency and barrenness of scientific journals; and on this subject a literary periodical thus expresses its opinion: "The existing scientific journals have, it strikes us, many grievous defects; first, men of acknowledged scientific talent rarely contribute to them, or at least do not put forth their strength in the contributions they transmit. Such persons are no doubt unwilling to have the fruits of their most pro^ found researches presented to the world mixed, up with such amass of crude and frivolous speculation as we generally find in these jourrials. Secondly, we think the editors mistake their proper vocation. Their leading object ought' to be to give us clear and popular accounts of the discoveries made at home and abroad, Showing, to the unlearned as well as the learned, the effect, application, and true value of each new truth added to art or science. Instead of this, we have the original speculations (often the mere sweepings of the study) of fourth and fifth-rate men, upon subjects of ninth and tenthrate importance, repulsively abstruse, and forbiddingly technical; and, along with these, whole pages, rough and round, from " the excellent work" of A., or B., or C, already in every body's hands, and given without note or comment. The editors ought to know that half a sheet upon a subject easily intelligible, and bearing on the business of life, such as steam navigation or gas light, is worth a volume upon the anatomy of gnats' legs, or the double refraction of a wren's eye. What is merely curious should not be excluded, but kept in its proper place. Nor is a good idea the worse for being new; but still it is better to be useful and popular, than to be original and trashy. Philosophical journals ought to be addressed not exclusively to men of profound science, who are few in number, and will not be satisfied with the scraps they get in such works, but to the mass of persons whom business or curiosity interest in scientific. pursuits, without having taste or time for deep researches. Such journals should be considered as the links that connect the learned with the industrious—the strainers and digesters through which the truths of philosophy must pass to fit them for assimilating with the system of active and busy life. The success of the Mechanics' Magazine, the Chemist, and other periodicals of that description, shows how ample the field of usefulness is in this department, if our journalists of a higher class would get into the tight track."—Scotsman.' As the present Number of the

Annals bears the name of Mr. Children, as an additional editor, we presume that it has been placed under a new administration, and that it has been found necessary to put forth greater vigour, or quit the field. If the editors of the Mechanics' Magazine and the Chemist, have no other gratification, they at least know that their, exertions have compelled other editors to set about improvement. The scientific literature of the country will be henceforth much better, and for this beneficial change the world will be greatly indebted to exertions, which (we will not stoop to the commonplace cant of zeal for the public) were made for ouj own benefit. We cannot, however, yet compliment the editors of the Annals, much as we may be disposed to imitate the parliamentary vice of sacrificing a principle to a flattering phrase, with having made any conspicuous improvement in the matter of their journal. There is much the same quantity of what is merely curious, and nearly the same deficiency of what is really useful. We first meet with—

A BIOGRAPHICAL ACCOUNT OF ASSESSOR JOHN GOTTLIEB GAHN.

Why Mr. Children, who we conjecture is the author of this paper, chooses to prefix Mr. Gahn's title, which is unusual in England, though very common in Germany and Sweden, we are at a loss to discover., What should we think of" Biographical Memoirs of President of the Royal Society Davy," or " ExciseCollector Wordsworth I" and if these modes of expression are strange, why, we ask, does Mr. Children introduce a similar mode, because the man was a foreigner, and had his title prefixed to his name in his own country? But, not to be hypercritical, we shall take from the paper an outline of Gahn's life.

J. G. Gahn was one of the most distinguished chemists Of the last fifty years. He was b.prn on Aug. 17th, 1745, at Woxna iron works, in South Helsingland, and was the son of Ilanns Jacob Gahn, treasurer to the government of Stora Kopporberg. He went to school at Westeras, and was afterwards •sent to the University of Upsala. His mind was early turned to scientific pursuits, witli a zeal which at once carried him rapidly forward, and made him study deeply as he went. While yet in the academy, he dropped a specimen of crystallized carbonate of lime, and the fall shattered it into fragments. By this accident the original nucleus of the crystal was developed, and Gahn, pursuing the idea which this suggested, and which would have been lost for any other person, succeeded, by cleavage, in extracting the rhomboid, which constitutes the primitive form of this mineral, from a great variety of secondary crystals. Bergman, to whom this observation and discovery were communicated, published, immediately afterwards, a dissertation on the forms of crystals, which called forth the wellmerited admiration of men of science. But while Bergman, says this author, reaped this honour from his essay, he had omitted to mention that it was the discovery of the pupil which bad furnished the basis of all the reasonings of the master. Bergman was distinguished for his candour ; he was as much beloved as admired; and we are rather slow to believe this questionable story of his observa'tions having been founded on the discovery of another, which he took care not to acknowledge. Gahn afterwards succeeded in analyzing the earth of bones, and in showing that it was phosphate of lime. The same substance, when occurring in,the mineral kingdom, has since baulked the efforts of analysts of considerable celebrity, and Gahn's success, therefore, reflects honour on his sagacity. The merit of this' discovery was attributed to Scheele, as it was first announced to the public in his works, without the name of Gahn being mentioned. The next thing in which he succeeded was to reduce manganese to a. metallic state; and though he is not now

deprived of the honour of having discovered this process, it was at first made known to the world by the works of Bergman. He next taught philosophers the scientific value of the blow-pipe, which, before his time, was only used by workmen, and drew up a concise summary of directions for its use, which were published in Berzelius's Elements of Chemistry. He was also the inventor of a balance, remarkable both for its extreme delicacy and the simplicity of the plan on which it is constructed, so that it can be made by any ordinary workman. In all these cases Gahn seems to have been so indifferent to celebrity, as to have made no effort to claim what was fairly his due. The author of the biographical memoir which we are now abridging, ascribes his unwillingness to come before the public, to a want of confidence in the value and completeness of his discoveries. He chose to revolve them again and again in his mind, and wished to submit them, according to the poets' rule, to the testof anine years' examination. Though this may probably have partly been his motive, we are willing to attribute his conduct to another cause. Those only1, we believe, are tenacious of celebrity who are destitute of tha't'thore solid enjoymenfwhich results from an active prosecution of the' business of life, and from energetically fulfilling the duties of a man and a citizen. 'Gahn was not 'a rtiere philosopher, deriving not drily celebrity, but perhaps even his' office, from his discoveries; he waS the active manager ahd conductor of several manufactories, and held a distinguished office in the political department of a free state. It" was probably from obtaining both advantage and honour from these two situations, that he was careless about that scientific celebrity1,11 to procure which'is the Object of so many intrigues, ancV so mudi'waiting by men who are'nothing'but philosophers; '"'"'"'''

Gahn's farther died wheti fae'was yourig; ahdleft'him'Ihnar^b^'clrcumstances, which compelled him to exert himself; and as he was destined to an employment about the mines, he took up his abode with the miners, and studied their practices till he had completely made himself master of all their knowledge. Having, in 1770, made his acquirements known, by an academic thesis on the improvement of iron foundries, he was soon afterwards appointed, by the College of Mines, to make experiments as to the melting of copper, at Fahlun. In consequence of his experiments, and by his recommendation, a new method of proceeding was immediately adopted, which saved a great deal of expense, and is followed to this day. He then acquired a part of the extensive works at Stora Kopporberg, where he settled as superintendent, and soon had an opportunity of obtaining wealth and adding to his reputation. During the American war, a sudden and a great demand was made for copper, and a very large order was sent to Fahlun, which Gahn, at his own risk, though others conceived it chimerical, undertook to complete. He succeeded, and not only added to his own wealth, butgained the increased confidence of all with whom he was connected. From the time of his first settling at Fahlun, in 1770, till 1785, Gahn took a deep interest in the improvement of all the chemical works of that neighbourhood; and, in conjunction with others, he established manufactories of sulphur, sulphuric acid, and red ochre, which were a source of great emolument to the proprietors. In 1780, the College of Mines, as a testimony of their sense of his exertions, bestowed on him a gold medal. In 1782, he received a royal patent as mining master; in 1784 he was elected a member of the Royal Academy of Sciences, at Stockholm; and inthesameycarhe was appointed Assessor in the Royal College of Mines. About the same period also he married Anna Maria Bergstrom, with whom he lived happily thirty-one years, and by whom he had one son and two daughters.

In 1773, he had been elected a chemical stipendiary to the Royal College of Mines; and from that time till 1814 every chemical problem the College had to decide was referred to him. In 1803 and 1804 a case occurred which evinced his skill. In consequence of the copper sheathing of a vessel having been corroded to a great extent, there^arose a prejudice against the Fahlun copper, and Gahn was appointed to ascertain if there were any' grounds for this prejudice. He demonstrated that the copper contained no pernicious ingredients, and it afterwards turned 'out that the copper of this vessel had not been obtained at Fahlun.

In 1778, Gahn began his political career, being in that year returned by the Mining Directory of Fahlun to the representative body of burghers. In the momentous discussions which took place in the Swedish Diet, in 1778, 1809, and 1810, Gahn took an active part, and was always a member of the constitutional committee. In 1795, he was chosen a member of the. committee for directing the general affairs of the kingdom. In 1810 and in 1812, he took an active part in the measures adopted for the maintenance of the poor, and for the promotion of agriculture.—. When it is considered that the mining district of Sweden which Gahn represented has long been distinguished for cherishing a love of freedom, that it has possessed numerous valuable privileges unchanged for ages, it is eulogium enough for Gahn to say, that his brother miners found in him a worthy representative, and a man adequate to the great trust reposed in him. It must be remembered that the period when he held this trust was one of peculiar delicacy and difficulty,—one when all the thrones of Europe were convulsed: and even Sweden felt the 'influence of that moral tempest which began at Paris. In this period of difficulty, Gahn acquitted himself with honour; and he is at this day as much endeared to his countrymen by the ardour and disinterestedness with which he defended their public

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