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these specimens, so that Breithaupt has proposed for it the name of iron-platinum. The subject has recently undergone a very thorough study by Daubrée, who from his experiments upon the native material shows that the presence of iron in proper proportion suffices to account for the polarity of the native specimens. He still more firmly establishes his conclusions by artificially producing magnetic platinum, similar to that which occurs in nature. An alloy of 99 parts of iron and one of platinum, after a complete fusion, instead of becoming strongly magnetic, did not give any trace of polarity. Two other alloys, of 75 and 50 parts of iron respectively, bebaved in very nearly the same manner. Alloys formed some time ago by Berthier, containing 78 parts of platinum and 21 of iron, although imperfectly melted, are, however, susceptible of magnetism. It appears, then, that however pronounced may be the magnetic power of the iron, the alloys where this metal predominates do not acquire polarity under the same conditions as do alloys obtained with a smaller quantity of iron. Thus an alloy of 17 parts of iron and 83 parts of platinum has very strong magnetic properties, so that we must admit that platinum alloyed with iron in proper proportions becomes exceptionally susceptible of acquiring the magnetic state. In nature this magnetic state would naturally be produced by strong induction, attributable to the magnetic forces of the globe; and Daubrée has therefore, as a last experiment, placed a small bar of the alloy during its fusion exactly in the plane of the magnetic meridian. As soon as it was solidified, it was inclined so as to be parallel to the inclination needle, until its cooling was complete, and it was then recognized that the bar actually presented at its two extremities very energetic magnetic poles, the upper end being the south pole of the needle, showing that the earth's magnetism had actually produced this effect. On heating the same bar to a red heat, and giving it the diametrically opposite position during its cooling, it was found that the magnetism of the bar was reversed by the earth's induction.-Bulletin Hebdomadaire, XVI., 40.

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PRECIPITATION OF METALS BY ZINC. Every chemist knows that when metallic zinc is placed in a solution of either copper or silver, the latter metal is precipitated. J. L. Davies has found it to be possible to precipitate nickel in a similar manner, it being necessary, however, to render the nickel solution strongly ammoniacal. The zinc is used in the form of filings, and the nickel is thrown down distinctly metallic and in a weighable condition. The experiments were made with solutions of the sulphate and the chloride of nickel.--21 A, April, 311.

ABSORPTION OF HYDROGEN BY METALS. Not long ago Troost and Hautefeuille announced that sodium, potassium, and palladium absorbed hydrogen to form alloys of definite composition. They now present the results of similar investigations with iron, cobalt, and nickel. These metals absorb hydrogen largely, but to different degrees under different circumstances, not forming genuine compounds. Thus an ingot of nickel under favorable conditions will absorb one fifth its volume of the gas. The same metal in an electrolytic film can be made to take up forty volumes, while pulverulent nickel can dissolve nearly one hundred times its bulk of hydrogen. With each of the three abovenamed metals the pulverulent or pyrophoric modification has the highest absorptive power, and the compact form the lowest. Finely divided iron was found to differ from cobalt and nickel in its power of decomposing water, a phenomenon which takes place slowly at ordinary temperatures, and rapidly at about 100° Centigrade. Iron thus resembles manganese more closely than either of the other metals. — 6B, March 29, 788.

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OZONE IN THE LIBYAN DESERT.

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Professor Zittel, during a recent journey in the Libyan Desert in Egypt, made some observations of atmospheric ozone, from which it appears that the air over the desert is richer in ozone than that at the oases and the valley of the Nile, the ratios being as 73 to 48. The Libyan Desert, therefore, seems to be the richest in ozone of all portions of Europe. The ozone was observed to be always less in the day: time than in the night-greatest during clear weather and with northwest or west winds. Vegetation has been generally looked upon as an important source of ozone, whereas Ebermayer says that in all wooded regions the air in winter

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is richer in ozone than in summer, and that therefore forests, as such, evidently do not exert any influence through their leaves, but possibly through their greater moistness. Zittel, however, thinks there is no relation between vegetation and atmospheric ozone.—Zeitschrift für Meteorologie, IX., 312.

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THE PHYSICAL PROPERTIES OF HYDROGENIUM. The interesting substance known to chemists as hydrogenium has been the subject of some physical measurements by Dewar, who has attempted to make a new determination of its specific heat and its co-efficient of expansion. The only condition under wbich hydrogenium is known to exist is that of an alloy with the rarer metals, palladium, platinum, etc. As the result of his experiments with palladium and hydrogen, the specific heat of hydrogenium is concluded to be almost exactly 3.4. The co-efficient of cubical expansion appears to be very nearly 0.00025.

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THE COMBUSTIBILITY OF IRON. The following elegant lecture experiment for illustrating the combustibility of iron was originated by the late Professor Magnus, of Berlin. A mass of iron filings is approached by a magnet of considerable power, and a quantity thereof permitted to adhere to it. This loose, spongy tuft of iron dust contains a considerable quantity of air imprisoned between its particles, and is therefore, and because of its comminuted condition, well adapted to manifest its combustibility. The flame of an ordinary spirit - lamp or gas-burner readily sets fire to the finely divided iron, which continues to burn brilliantly and freely. By waving the magnet to and fro, the showers of sparks sent off produce a striking and brilliant effect.

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NEW METHOD FOR ASSAYING IRON. W. N. Hartley recommends a new and beautifully simple method of assaying iron ores, in which the only apparatus needed is a balance without weights, and a burette. To begin with, a quantity of pure iron wire is taken (about five grammes), and balanced by a sample of the pulverized ore. The ore and wire are then separately dissolved, and each solution titrated in the usual manner by permanganate

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Ple” TEB inter

= X. Here

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of potash. Then, to get the percentage of iron in the ore, the

100m following simple calculation will suffice: m and n are the quantities of permanganate solution used respectively for the ore and the wire, and x is the value sougbt. The method gives remarkably accurate results, even in the hands of beginners.-21 A, May, 410.

TO DETECT LEAD IN THE TIN LINING OF VESSELS. The following simple test may be found of great service where it is desired to determine the presence of lead in vessels used for canning fruit, etc. M. Fordos directs that a carefully cleansed portion of the lining should be touched with a drop of nitric acid, whereby both metals (if present) are oxidized, the tin to stannic acid and the lead to nitrate of lead. By slowly heating the acid will be driven off, when the spot is to be touched with a drop of solution of iodide of potassium. If lead is present the spot will turn yellow by the formation of iodide of lead. The iodide has no action upon tin.--6 B, XII., 1875.

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UTILIZATION OF THE PYRITE DEPOSITS OF THE BLUE RIDGE.

Professor T. Sterry Hunt, in a recent communication to the New York World, reiterates the views upon this subject which he advanced some two years ago at the Portland meeting of the American Association. He then proposed to utilize the pyrite deposits of the Blue Ridge as a source of sulphuric acid, with which to convert into fertilizers the phosphates of South Carolina on a large scale. Certain objections having been made to this proposition upon economical grounds, Professor Hunt reviews this side of the question, and places it in a very favorable light. He argues that with easily accessible beds of a high grade of pyrite or sulphur ore, like that of Spain, we might compete successfully with Sicilian sulphur, even if this were free from duty.

Of this pyrite, which contains a small percentage of copper, Great Britain imports and consumes about 400,000 tons annually. The acid from this ore serves for the greater part of her soda and fertilizer manufacture; and having thus utilized the sulphur, she extracts from the residne by solution several thousand tons of copper, leaving behind a nearly pure

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oxide of iron, which is itself consumed in the puddling and blast furnaces. In view of these facts, Professor Hunt hopes to see a similar use made of the great deposits of pyrite, rich in sulphur and often in copper, which abound in the Blue Ridge in Virginia, North Carolina, and Tennessee. Large quantities of these ores are now being treated for the manufacture of copper at Ducktown, Tennessee, and at Ore Knob, North Carolina ; and many other points in this region, in the opinion of Professor Hunt, are destined to become the seats of an important copper industry. It therefore becomes a question how those ores which are richest in sulphur may be most advantageously brought into contact with the abundant phosphates of the South Carolina seaboard. The extraction of copper as a secondary product from these ores will enable us to make acid cheaply, and to supply cheap fertilizers to the cotton-fields of the South. The fear having been expressed that these ores might contain notable quantities of arsenical compounds, Professor Hunt asserts them to be quite as free from this impurity as the Spanish ores so largely utilized in England. Upon this point, he furthermore remarks, the exceeding rarity of arsenical compounds in this region was long ago pointed out as a significant fact by Professor Henry Wurtz, of New York, in a paper “On the Cobalt and Nickel Ores of North and South Carolina,” in the American Journal of Science for 1859; and this is confirmed by the experience of those who have been familiar with the metallurgical treatment of the pyritous ores of Ducktown and of Ore Knob, already mentioned.

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NEW VIEWS OF CHEMICAL AFFINITY. Dr. E. J. Mills bas made an interesting application of principles first evolved by Esson to some observations made by Dr. Gladstone, and published in 1855 in his work entitled “Circumstances Modifying the Action of Chemical Affinity.” Mr. Esson had in fact shown that when a substance undergoes chemical change, the process takes place at a rate that has a relation to the mass of the substances acting upon each other at any given moment during the process, and the relation between the tine and the quantity of the chemical still unchanged at any moment may be expressed either by a complex analytical formula or by a logarithmic curve. This

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