.~lechanics, Physics, and Chemistry. (except the one for the Evening Post, which was sent to France.) Capt. 180
E. may now write volumes in regard to the theory of his engine, and not produce the least impression; but if he wishes to convince, he has only to put one of his engines at work, and invite those competent to judge, to examine [t and report, and he will do more in one week (if successful) to establish his fame, than by years of mysterious movements, however well supported by kind friends, who, at a later period, must condemn the same policy they now approve. True science should never seek the dark, but soar on eagle's wings. WATT.
Separation of Gold fco)n ~rsenical Pyrlteg, according to Platlner~s J]iethod. By W. GUETTLER.* The mines of Reichenstein, in Silesia, abandoned for more than five centuries, have been recently opened with advantage, in consequence of the application, on a large scale, of a method invented by Professor Plattner, ibr separating gold from the waste of arsenical ores. The ore at Reiehenstein is an arsenical pyrites, containing about ~200 grains of gold in the ton. The ore is roasted in a reverberatory furnace surmounted by a large condensing chamber, in which the arsenious acid is condensed as fast as it is volatilized. There then remains on the floor of the furnace, oxide of iron mixed with a certain quantity of arsenic, together with the whole of the gold. This is placed in a vessel so arranged that a current of chlorine can be passed through it, by which the gold and iron are taken up, and aherwards separated fl'om the residuum, by the aid of a certain quantity of water, and the gold is afterwards precipitated from this solution by sulphuretted hydrogen. To prevent the admixture of iron at this stage, a small dose of hydrochloric acid is added to the solution before the sulphuretted hydrogen is introduced. The auriferous compound having been separated from the liquor, is washed and heated in an open porcelain crucible, to drive off'the sulphur, by which the gold is reduced to the metallic state by fluxing it in the usual manner. This simple and ingenious method, which has made it worth while to re-open the Reichenstein mine, is equally applicable to the vast quantity of refuse accumulated near m~ny other old works. In awarding the Council Medal, the Jury have desired in this case to associate the name of Professor Plattner, the inventor of the method, with that of M. Guettler~ who has brought it into operation on a large scale. Translated for the Journal of the Franklin Institute.
,Method of Raising Heavy Weights under Water. From a recent number of Cosmos, an admirable w~ekly scientific periodical, edited in Paris by the Abb6 Moigno, best known perhaps, in this country, by his excellent work on electric telegraphs, we extract the following account of a recent experiment : - - " O n Saturday last,, Doctor +From the Reports of the Juries of the Exhibition of the Works of Industry of all .Nations, 1851. London.
On the Undulatory Theory of ;Light.
t81
Gianetti, inspecting physician of the waiers of ¥crdese, (Corsica,) invited us to he present at an experiment, at the same time very curious and very important, on the margin of the Seine, near the bridge des ~rts. The object was, by means of a small balloon of about a foot and a half in diameter suddenly inflated at the bottom of the water, to lift to the surface a weight of one hundred kilogrammes, (.225 lbs.) The modus operandi of the Doctor is very rational and very rumple; he caused to be constructed in very stout metal, a vessel with two compartments and three tubulures; by two of these tubutures he pours into one compartment, bicarbonate of soda, into the other, hydrochloric acid; on the third tubulure he screws the balloon of leather, or some very strong impermeable stunt: In the experiment at which we were present, the vessel with the balloon was fixed to the ring which united the four weights of ~5 killogrammes, (56 lbs.,) before the weights were lowered into the water, and workmen lowered the whole to the boltom of the river. A thin cord which Mr. Gianetti hehl in his hand, had been fixed to a small arm of a lever upon the vessel; by pulling it he opened a stop-cock, and established a communication between the two compartments of the vessel, so as to mix the two liquids; the acid and salt reacting upon each other produce a very abundant disengagement of carbonic acid; immediately the balloon became inflated, developing a considerable aseensional force, and we saw it rise to the surface, bringing with it the four weights. ]~.EMARKS.-----~e cannot say that there is anything of value in this, beyond the well known and long applied principle in use in our floating docks and camels, where caissons filled with water are first sunk and placed around the mass to be raised, and then the water being replaced by air, by means of pumps, the whole body rises in the water; but it is possible that M. Gmnettt s method of replacing the water by gas may be available in some eases where the other, less expensive and i:nore effectual method could not be applied. ED. Translated for the Journal of the Franklin Institute.
Exfleriments on the Undulatory Theory of Light. In a former number of our Journal, we have brought to the notice of our readers the extremely ingenious and delicate experime~t by which M. Foueault, of Paris, confirmed the undulatory theory of light, and de,nonstrated the falsity of the emission hypothesis. The following article, which we translate from the pages of the Abb5 Moigno's Cosmos, filrnishes another no less extraordinary confirmation of the same theory by the application of extreme mechanical nicety: " M . Nobert, a German optician, has succeeded in tracing upon a surt:aee of polished glass, perfectly parallel lines, the distance of which apart is only the five-thousandth of a millimetre, (0.000008 inch,)the length of a wave of light, and has desired to make his marvellous skill subserve the triumph of the undulation theory. For this purpose he has executed three plates, which we did not wish to describe until we had seen them Yon. XXVIo--TIHRn S~:a~s.--No. 3.--NEPTI:~gEn,1853. 16