strontia alone may occasion some difficulty by reason of the white precipitates of double hyposulphites, which they form with the same reagent; but it is very rare to meet them along with potassa, and they are very easily detected and removed.
Prevention of Fires in Coal-Mines.—In an address on fires in mines, Mr. Richard P. Rothwell affirms that the most efficient preventives of such fires, from whatever cause they may come, are to be found in education, in increased knowledge of the causes of fires, and a better appreciation of the working of these causes. Mine-managers he would compel to undergo strict examinations, nor would he allow any one to undertake the responsible duties of this place without a certificate of competency from a qualified board of examiners. He would not, however, stop here, but would have the miners themselves instructed as to the causes and preventives of the dangers they meet with in their work. Special free instruction upon these points might be furnished at every colliery; and this could doubtless be accomplished by encouraging the giving of popular lectures, by practical miners and engineers, on subjects of interest to the miner, and by giving small prizes to those who pass the best examination on subjects of daily practical application in their calling. Greater knowledge always makes better workers, and mine-owners would find in this a good return for the expense incurred.
Economy of the Electric Light.—In a series of experiments on electric light, Prof. W. A. Anthony used an electro-magnetic machine of the Gramme pattern, driven by a five-horse Brayton petroleum-engine. The engine consumed a little over 612 pounds of crude petroleum per hour. The lamp used in the engine, by which the explosive mixture is fired, had a one-inch flat wick, and consumed 29.8 grammes (459 grains) of oil per hour. The power resulting from the motion of the engine, when applied to the electric machine, produced a stream of electricity or electric light having an illuminating power equal to that of 234 of the lamps mentioned, showing that three times more light may be produced from a given quantity of oil, if its energy is converted first into mechanical power and then into electricity, than if the oil is directly burned in a lamp.
Southern Illinois Academy of Science.—The Southern Illinois Academy of Science, a newly founded scientific association, with its seat at Carbondale, has for its objects the investigation—1. Of the ethnology and history of Southern Illinois, including its antiquities and aboriginal remains; 2. The geology, botany, and zoölogy, of that section; and, 3. To encourage the production of original papers on the above, and on special mathematical, astronomical, and meteorological subjects, as well as on the origin and meaning of the names given to localities by the Indians and the first white settlers of the country. The Academy is engaged in making a collection of materials illustrative of the field of research to which it has devoted itself, and has issued a circular calling for contributions of archaeological and aboriginal remains, historical notes, maps, sketches of mounds, natural history specimens, etc. The Secretary of the Academy is Prof. Granville F. Foster, Carbondale, Illinois.
Threatened Eruption of Mount Vesuvius.—For many weeks Mount Vesuvius has been threatening an eruption. Prof. Boyd Dawkins, who visited the volcano in January, found, on arriving at the mouth of the crater, that it was filled with dense vapor like a fog. A low, roaring noise could be heard, and occasionally there was a flash of light, probably the reflected glare of the lava surging about in the volcano. Undismayed by these symptoms of internal disturbance, Prof. Dawkins went down seven or eight feet below the crater's edge, and found that he could light pieces of paper in holes which he dug with his hammer in the black ash on the inside. He is of the opinion that Vesuvius performs the duty of a safety-valve to a very large portion of the earth. At present the mountain is in a very restless state, and there may be an outbreak at any moment. The event is looked for with great interest by the inhabitants of Naples, as it will bring sight-seers from all parts of the world to their city.
The Challenger Collection.—The collections of marine animals made by the Challenger Expedition are declared by Prof.
