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.

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 which 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.

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.

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 The ore and wire are then separately dissolved, and each solution titrated in the usual manner by permanganate

ore.

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

100m

following simple calculation will suffice: = x. Here

m and n are the quantities of permanganate solution used respectively for the ore and the wire, and x is the value sought. 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.

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 residue by solution several thousand tons of copper, leaving behind a nearly pure

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.

NEW VIEWS OF CHEMICAL AFFINITY.

Dr. E. J. Mills has 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 time 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

equation, which may be called Esson's equation, on being applied to the numerous exact observations recorded by Gladstone, leads Dr. Mills to the conclusion that 54 per cent. of the discordances between the theory and the obser vations are such as would on the average be found in any very good analytical work, 33 per cent. occur in ordinary good analytical works, and the remaining 13 per cent, lie on the average within the limits allowable in such estimation of colors as Dr. Gladstone made. The ordinary equations of chemistry represent the result of distributing atomic weight, and give no account of the work done. Esson's equation and conclusions worked out by Gladstone, on the contrary, represent a dynamic process as well as the distribution of weight.-7 4, XLVIII., 246.

WATER OF CRYSTALLIZATION.

Professor Guthrie states that the absorption of heat, which occurs when the salt is dissolved in a liquid, depends not only on the relative specific heat of the salt in the liquid, but also on the molecular ratio of the resulting solution. This ratio declares itself, first, optically by the refractive index; second, by the density; third, by the heat absorbed when a saturated solution is mixed with the medium; and, fourth, by the heat absorbed when the salt itself was dissolved in a certain quantity of the medium. The conclusion which he draws from his observations is that every salt soluble in water is capable of uniting with water in a definite ratio, forming definite solid compounds of distinct crystalline forms and constantly melting and solidifying temperatures.-12 A, XI., 59. VIDAL'S APPARATUS (EBULLISCOPE) for the DETERMINATION OF THE AMOUNT OF ALCOHOL IN WINE, ETC.

The following instrument, an improvement on that originally devised by Vidal, it is claimed will indicate accurately the percentage of alcohol in liquids in less than ten minutes, using but little of the liquid. It depends upon the fact that sugar, resin, citric and tartaric acids do not change the boiling point of alcohol in which they may be dissolved, and consequently the determination of the boiling point will show the amount of alcohol present in an aqueous liquid. It consists of a conical boiler, closed at the top with a screw-cap

having two apertures in it, through one of which a thermometer, bent at right angles, is inserted, in such a way that the bulb can be immersed in the liquid or the vapor at pleasure, while upon the other is screwed a condenser, consisting of two concentric cylinders. At diametrically opposite points at the bottom of the boiler the ends of a small curved spiralshaped tube are inserted. This tube, filled with the same. liquid as the boiler, passes directly through the chimney of a lamp, and consequently receives upon a small surface the whole of the heat of the lamp. The fluid, thus gradually warmed, circulates through the tube and the boiler, until the whole of it has reached the boiling point, when the thermometer becomes stationary, and will remain so for ten minutes. A horizontal movable scale is fixed to the top of the boiler, by comparing which with the thermometer the amount of alcohol is indicated in degrees from 0 up to 25.-14 C, CCXIII., 87.

SPECIFIC HEAT OF CARBON, BORON, AND SILICON.

In 1819 Dulong and Petit discovered that when the specific heat of a solid element was multiplied by its atomic weight, the product was a constant quantity in the neighborhood of 6. Later, however, it was found that carbon, boron, and silicon were apparent exceptions to this rule. These elements have been studied in this direction by many experimenters with very discordant results; as, for instance, some found that the different modifications of carbon had the same specific heat, others that they varied widely. The subject has lately been thoroughly worked up by Dr. H. Friedrich Weber, whose results at last seem to be conclusive. Carbon he examined as diamond, graphite, coal, and charcoal, and boron and silicon in their crystalline varieties. His experiments were conducted at temperatures varying from -80° to +1000° Centigrade, and with the finest modern apparatus. With all three of the elements above named the specific heat increases very rapidly with the temperature. At 600° for carbon and boron, and at 200° for silicon, this increase almost ceases, and the specific heat remains nearly constant. Below 600° the different modifications of carbon give different results, but at and above this temperature they coincide. The constant final values, at the temperatures