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deficiency in the strength of the acid, may be seen by placing in the spheroid a piece of cold silver, when violent action, of course, takes place, nitrous fumes being given off, and nitrate of silver formed. remarkable effect may be produced, owing to this repulsion between liquids and heated solids, if a large spheroid of water be formed on a surface nearly flat, and a small bar of white or red hot iron be then thrust into the middle of it. Contact being impossible between the bar and the water, the latter forms a ring at some little distance from the heated bar, presenting very much the appearance of Saturn and his ring. Whether any real analogy exists between the two effects, or whether the causes be in any way connected, further researches into the nature of that anomalous appendage of the planet may perhaps decide.
We have now passed in review the most important phenomena presented by water and other liquids, when thrown into vessels raised to a high temperature. We found, in the first place, that water may be made to assume the globular form, when placed in a cup heated only to 340°, which is less than 130° higher than its boiling point; and that the temperature necessary to convert other liquids into spheroids bears some proportion to their several boiling points—that for alcohol being 273°, and that for ether, 140°. Secondly, we found that the rapidity with which water in the spheroidal state evaporates, is in proportion to the temperature of the heated vessel containing it, but that the evaporation of water in a spheroidal state is, at a temperature of 400°, fifty times more slow than that of ordinary boiling water at 212o. On examining into the temperature of liquids in the spheroidal state, we arrived at the remarkable result, that whatever the temperature of the containing vessel may be, that of the spheroids is invariable, and always below their boiling points. Thus, a spheroid of alcohol always stands at 170°, or 3° below its boiling point; one of ether is always 5° below, or 95°; and liquid sulphurous acid, which boils at 14', never reaches even that low temperature when in the spheroidal state, but continues far colder than melting ice, even though the crucible in which it lies be all the time at the most intense white heat. Fifthly, we found that the only way of explaining this low temperature of spheroids, is to suppose that they have the property of reflecting, in a very perfect manner, the radiant heat emanating from the sides of the hot crucible, and are in this way protected from the scorching rays which would otherwise cause them to burst violently into steam. In the sixth place, it appeared that, with scarcely any exceptions, all liquids may be made to pass into the spheroidal state. And, lastly, there appeared strong evidence to prove that spheroids are never in absolute contact with the vessel containing them.
Prac. Mec. and Eng. Mag. To be Continued.
Extract from a memoir upon the action of the Perchloride of Gold
upon the Hyposulphite of Soda.* It is known that, by mixing determinate quantities of perchloride of gold and hyposulphite of soda, previously dissolved in water, a liquid is prepared which is now used to fix daguerreotype pictures. The chemical nature of this liquid is completely unknown: we thought that a thorough examination of its composition and properties would furnish the means of remedying some of the inconveniences which it presents. The result has shewn that we were correct.
To obtain this liquid, the preparation and use of which are due to M. Fizeau, we dissolve one part, by weight, of chloride of gold in five hundred parts of pure water, and three parts of crystalized hyposulphite of soda in the same quantity of water. The solution of gold is then poured little by little into that of the soda, stirring the whole time: the liquid at first reddens, but soon becomes colorless. It is 100 dilute to be analyzed, and as it is impossible to concentrate it, we were compelled to have recourse to the mutual reaction of chloride of gold and hyposulphite of soda, dissolved in very small quantities of water. A liquid obtained under these circumstances, is very abundantly precipitated by alcohol, at 40°.
The reaction is the same as when we take the re-agents more dilute, only the mixture must be made with more precaution; especially, after each addition, we must wait until the discoloration is complete, otherwise we cannot avoid the formation of a brown substance, which is difficult to be got rid of, and which is the result of the reaction of the perchloride of gold upon the products first formed.
The precipitate obtained by alcohol from this solution is a mixture of several different salts; it is almost altogether composed of a salt which we are about to describe, but it contains, besides, variable quantities of all the products contained in the supernatant liquid.
To purify it, it is necessary to redissolve it several times in succession, in a small quantity of water, and to precipitate it each time by absolute alcohol.
The salt thus purified is perfectly colorless, crystalizes in needles, insoluble in strong alcohol, and but slightly in ordinary alcohol; but, on the contrary, excessively soluble in water. Its taste is sweet.
Its aqueous solution possesses all the properties of M. Fizeau's li. quid; and, in fact, M. Lerebours, who has carefully compared the action of these two liquids, even gives a preference to the solution of our salt, in consequence of the richness of the tones which it gives to the picture. It is the active material of M. Fizeau's liquid, freed from all foreign
Careful analyses shew its composition to be S: 02 Au0° +3 (S? 02 Na. 0) + 4HO.
• In a memoir by Messrs. Fordos & Gelis, published in a late number of the “Annales de Chimie," they describe a new salt, to wbich we desire to call attention, as likely to be of use to those engaged in daguerreotyping.
It is, therefore, a double hyposulphite of gold and soda, with four equivalents of water.
The investigation of this salt, and of the supernatant liquid, shews that the action of the perchloride of gold upon the hyposulphite of soda, may be represented by the following equation: 8 (S' 02 Na. O) + Cl Au + 4 (HO) = 2 (S* O Na. 0) + 0
S4 SPOAu. 0,3 (S. 02 Na. 0) 4 HO. There is therefore formed a bisulphuretted hyposulphate of soda, which plays no useful part in fixing the daguerreotype pictures; we may even say that, by the ease with which it abandons its sulphur under the influence of heat, it may contribute to the formation of those black spots which so often compel us to abandon the most perfect impressions. It is also probably owing to its presence that the change which M. Fizeau's liquid undergoes, when kept, is to be attributed. All those who have frequent occasions to use it, know that it can scarcely ever be kept for a month. This inconvenience renders it necessary for each ainateur to prepare it for himself, which is difficult. For although the preparation is simple and easy for those who are accustomed to chemical experiments, it is by no means so for amateurs: to succeed, they must conform exactly to M. Fizeau's instructions, and especially employ perfectly pure materials, which it is not always easy to find in commerce.
We believe, therefore, that it will be found useful to substitute the salt which we have just described, in place of the liquid of M. Fizeau; it will then suffice, in order to obtain a suitable liquid, to dissolve one and a half parts, by weight, of the salt in one thousand of water. Such was the liquid used by M. Lerebours. In conclusion, this substitution will permit us hereafter to transport, in a very small bulk, quantities of this salt, which represent enormous masses of the liquid, and this last advantage will be particularly felt by traveling photographists.
Ann. de Chim. et de Phys., April, 1845.
Experimental Researches into the Properties of the Iron Ores of
Samakoff, in Turkey, and of the Hematite Ores of Cumberland, with a view to determine the best means for reducing them into the cast and malleable states; and on the relative strenyth and other properties of cast-iron from the Turkish and other Hæmatite Ores. By William FAIRBAINN, M. Inst. C. E.
In the smelting and manufacturing of the poorer iron ores, as they are commonly called, being those in which a large proportion of alumina, silica, and other foreign matters are contained, many important improvements have in modern days been effected; but in the reduction of the richer sorts-hæmatite ores, those more nearly approaching pure iron, with very little admixture of other substances, there has been scarcely any change, from the old and expensive methods, which have for several centuries prevailed in this and other countries. It is remarkable that the proprietors of the richer minerals
should have allowed the makers of iron, from ores of leaner quality, such as the blackband and kidney ores, to have so far outstripped them.
Except the successful experiments of Mr. Heath, at the Works of Porto Nuovo, in the East Indies, and the attempts now making by the Cleator Company, near Whitehaven, there are few instances of improvements in the smeltings of rich ores, either in this country or on the continent. It has been stated, that the Swedish iron manufacturers have introduced some alterations into their works, but they appear to be of minor importance, and to be scarcely entitled to the name of improvements upon the old process used in that country for a long series of years.
It is to ,Mr. Ohanes Dadian, an active and enterprising Armenian, in the service of the Sublime Porte, that we are indebted for the present inquiry; and by that gentleman's determination to surmount every obstacle, and to solve the doubts of some eminent chemists, the present results were obtained. Amongst other duties devolving upon Mr. Dadian, in his recent visit to this country, was that of placing in the hands of competent persons, some samples of ores which were sent from Turkey, for the purpose of experiment. The first samples were small in quantity, but a more recent supply, accompanied with some specimens of bituminous coal, enabled the experimenters to enter upon the subject with increased confidence, and to pursue the inquiry with much greater prospects of success. In addition to this, Mr. Dadian had full power to engage persons duly qualified for the investigation, and whose skill and practical knowledge would entitle them to the support and confidence of their employers.
In consequence, Mr. W. N. Clay was engaged as chemist and metallurgist, and Mr. John Hague as engineer.
As the greater part of the experiments were conducted under the superintendence of these gentlemen, their separate reports are given in the order in which they were made; and to prevent confusion the facts are recorded as they occurred, from time to time, in the experiments.
Previous to Mr. Dadian's visit to England, he had collected information relative to the fuel, limestone, &c, in the district of country where the ore is found; and from the abundance and quality of the materials, it is presumed that a moderately cheap iron of very superior quality may be obtained.
From the description of the country, as given by Mr. Dadian and by Mr. Zohrab, who visited the locality some years since, it appears, that the ore is brought down the rivers from the higher districts, and is deposited in the lower valleys, at a short distance from the sea; extensive tracts of country are thus covered to a depth sufficient to Msure an almost inexhaustible supply.
Before any definite plan could be adopted for the reduction of the ores, it was deemed necessary to ascertain, by careful analysis, their composition and value, and for these objects Mr. Dadian, when last
n Paris, consulted Monsieur Dumas, the chemist, and from that gentleman he received a favorable report: that report is not in the author's possession, but from statements received, it appeared only to have differed in a slight degree from that of Mr. H. H. Watson, of Bolton, whose analysis of the samples (which may be taken as a fair average of the whole) gaveOne atom 28 + one atom
protoxide of iron. Two atoms 56 + three atoms 24 = peroxide of iron.
84 metal + 32 oxygen
116 black oxide. Then 116 : S4 : : 88 : 63.72 + quantity of metal per cent. in the ore in question by theory.
In this statement Mr. Watson observes, “that the oxide readily dissolves, when the ore is heated in powder with hydrochloride acid;" and by thus treating 100 grains of the ore, he obtained a solution of the oxide, and had 12 grains of siliceous earth undissolved; the proportions would therefore beProtoxide of iron
100 From the above it is evident that the ores are nearly pure oxides of iron; they are rich in quality, highly magnetic, and may be easily separated from extraneous maiter by the magnet. In some of the processes this separation may or may not be necessary, but in case the silica be found injurious, the process of cleansing may be effected by a series of magnets fixed on the circumference of a wheel, which, in moving through the loose ore, would attract the iron and carry it round to a revolving brush, acting upon the periphery, and thus deposit the metal into a receiving box on the opposite side. This is probably the best method for obtaining the perfectly pure oxides; but the most expeditious mode would be to cleanse it with a fan, in the same way as farmers winnow grain, by blowing the lighter particles to a distance, and allowing the metallic granules, as being of higher specific gravity, to fall short into a separate receiver. A third method would be, to wash the ore in a current of running water, and thus free it from all superfluous matter not required in the process of manufacture. But in these different cleansing operations, an excess of the siliceous earths is assumed, and moreover that these mixtures are detrimental to the process of deoxidation, to be effected either before or aster the change in the furnace.
Now, it is not altogether clear that such is the case, and in the absence of experiment it is reasonable to suppose, that instead of these earths proving injurious they might be found usesul, in combining with the limestone as a flux, and thus vitrifying the silex at the same instant the deoxidating process is going on.
These opinions are entitled to some weight, as the separate reports of Mr. Clay and Mr. Hague (although their views are not altogether