Page:Popular Science Monthly Volume 13.djvu/785

Rh he be disheartened by the temporary failure of his experiments, nor at the slowness of his processes. "Bunsen was obliged to evaporate forty-four tons of the waters of the Dürcheim springs in order to obtain two hundred grains of his new metal, cæsium. It took Berthelot several months to form, by a series of synthetical operations, an appreciable quantity of alcohol from water and carbon, derived from carbonate of baryta. Many years ago, in the laboratory of Wurtz, a poor student was carrying from one room to another a glass globe which contained the product of a month's continuous labor, when the bottom of the globe fell out, and the contents were lost. Nothing daunted, he recommenced his month's work, and brought his research to a successful issue. Above all things, the chemist must be true. He must not allow his wishes to bias his judgment or prevent him from seeing his researches in their true light. He must not be satisfied that his results appear true, but he must believe them to be true; and, having faithfully performed his experiments, he must record them faithfully. He may often be obliged to chronicle his own failures and describe operations that tell against his own theories, but this hard test of his truthfulness he must not shrink from."

A New Form of Galvanic Cell.—When rods of zinc and copper are placed in mercury, and connected with an electrometer, no change is observed; and, whether the zinc and copper are in contact outside the mercury or not, the amalgamation of the zinc appears to proceed at the same rate. According to a communication to the London Royal Society, from Profs. Ayrton and Perry, of the Tokio Engineering College, the impurities and great conductivity of the zinc, with the great liquidity of the amalgam, and the close proximity of foreign particles to pure metal, cause the amalgamation to be produced by local action alone, so that the supply of available chemical energy for the production of a current from the zinc to the copper is exceedingly small: at low temperatures, when the amalgam loses its liquidity, such an arrangement would, the authors conjectured, become a simple voltaic cell. To test this they substituted, for zinc, magnesium, whose amalgam is nearly solid at ordinary temperatures. Strips of platinum and magnesium, metallically attached to the electrodes of the electrometer, were dropped into mercury which had been washed with distilled water and then well dried. There was a sudden large deflection, afterward fluctuating very much, but keeping always on the same side of zero. On successive reversals of the electrometer key, the deflections to the right and left of zero were found to be nearly equal to one another. To determine the electro-motive force of the arrangement, strips of platinum and magnesium, scraped very clean, were dipped into pure mercury. The maximum electromotric force obtained was 1.56 volts—equal to one and a half time the electromotrive force of a Daniell cell. The authors remark that, by mechanical or other means, or by using another metal than magnesium, it may be possible to give constancy to this arrangement; and as its internal resistance is extremely small, the cell may be of great practical use for the production of powerful currents. As an amalgam may be easily separated into its components by distillation, such a cell might be kept in action for an indefinite time.

An Interesting Geological Question.—Though the Triassic rocks of New Jersey and the Connecticut Valley are commonly regarded by geologists as intrusive igneous rocks, the direct proof of their intrusive nature is not readily accessible. Indeed, some geologists have supposed that, so far from being intrusive, they were formed contemporaneously with the shales and sandstones amid which they occur, as a bed of igneous rock at the bottom of a shallow sea in which the stratified rocks were being deposited. But Mr. I. C. Russell shows, in the American Journal of Science, that these trap-rocks were forced out in a fused state among the sedimentary strata after the consolidation of the latter, and hence that they are more recent than either the rocks above or below them. The evidence of this he finds in a ravine on the western slope of the First Newark Mountain, directly west of Westfield, New Jersey. Here the trap-rock which appears in the bed of a little brook presents its usual characteristics of a hard, bluish,