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Scientific American Supplement, No. 470, January 3, 1885电子书

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作       者:Various

出版时间:2018-02-27

字       数:17.4万

所属分类: 教育 > 外语 > 实用英语

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Great ingenuity is being shown in the arrangement of new forms of primary batteries. The latest is that devised by M. Jablochkoff, which acts by the effect of atmospheric moisture upon the metal sodium. A small rod of this metal is flattened into a plate, connected at one end to a copper wire. There is another plate of carbon, not precisely the same as that used for arc lights or ordinary batteries, but somewhat lighter in texture. This plate is perforated, and provided with small wooden pegs. The sodium plate is wrapped in silk paper, and pressed upon the carbon in such a manner that the wooden pegs penetrate the soft sodium. For greater security the whole is tied together with a few turns of fine iron wire; care being taken that the wire does not form an electric contact between the sodium and the carbon. The element is then complete, the carbon and the small copper wire being the electrodes. The sodium, on exposure to the air, becomes oxidized, forming caustic soda, which with the moisture of the air dissolves, and drains gradually away in the form of a concentrated solution; thus constantly exposing the fresh surface of the metal, which renders the reaction continuous. The price of the element is lower than would be expected at first sight from the employment of so expensive a metal. The present cost of sodium is 10 frs. per kilogramme; but M. Jablochkoff thinks that on the large scale the metal might be obtained at a very low figure. The elements are grouped in sets of ten, hung upon rods in such a manner that the solution as formed may drain off. Such a battery continues in action as long as the air contains moisture; the only means of stopping it is to shut it up in an air-tight case. The electro-motive force depends on the degree of humidity in the air, and also upon the temperature.
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FLOW OF WATER THROUGH HOSE PIPES.

IRON PILE PLANKS IN THE CONSTRUCTION OF FOUNDATIONS UNDER WATER.

AN ATMOSPHERIC BATTERY.

SOUND SIGNALS.

TREVITHICK'S ENGINE AT CREWE.

PLANETARY WHEEL TRAINS.

THE FALLACY OF THE PRESENT THEORY OF SOUND.

THE ATTOCK BRIDGE.

THE ELASTICITY OF METALS.

THE HARRINGTON ROTARY ENGINE.

TESTING CAR VARNISHES.

THE FIXATION OF MAGNETIC PHANTOMS.

A CHIPPENDALE SIDEBOARD.

LIQUEFACTION OF THE ELEMENTARY GASES.

EXAMINATION OF FATS.

NOTES ON NITRIFICATION.2

ANILINE DYES IN DRESS MATERIALS.

CASE OF RESUSCITATION AND RECOVERY AFTER APPARENT DEATH BY HANGING.

THE INVENTORS' INSTITUTE.

THE NEW CENTRAL SCHOOL AT PARIS.

RESEARCHES ON THE ORIGIN AND LIFE-HISTORIES OF THE LEAST AND LOWEST LIVING THINGS.

THE SCIENTIFIC AMERICAN SUPPLEMENT.

PATENTS.

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