350 abundant as with copper, the size of the plates being the same in bot cases, so that a ten-pair battery of zinc and iron yields in seven minu (if the polar wires are made to dip into water) as much detonating oss a battery of zinc and copper of the same dimensions. But it is only the quantity of the electric current that is greater in the case of zinc and iron; the tension is smaller. At the first moment of immersion, the quantity also is greater with zinc and copper; bnt the copper soon becomes covered with a dark film of oxide [sulphuret?], while the iron remains clean,—and this film interferes with the electrical conduction between the copper and the liquid. When a pair of zinc and iron plates, and a pair of zinc and copper, are left in action for twelve hours, the following loss of metal is observed: Copper, 0; zinc connected with it, 96 grains; iron, 6 grains; zinc connected with it, 74 grains. It appears, then, that a small quantity of iron is dissolved; and of the zinc connected with copper more than of the other zinc,--and yet the quantity of the current is greater with zinc and iron. [Hence, zinc and copper produce a greater amount of purely chemical action]. (Martyn Roberts, Phil. Mag. J. 16, 142; 19, 106.) Zine and iron produce a more copious current than even zinc and silver or zinc and platinum, both in dilute sulphuric and dilute nitric acid; and the plates of the zinc and platinum pair must have a surface three times as great as that of the zinc and iron to yield the same quantity of electricity. But the intensity of the current excited by zinc and iron is If the quantity of electricity yielded by zinc and iron be 260, that yielded by zinc and copper is 100: when the plates are connected by a wire 50 feet long, the quantity yielded by zinc and iron is 337, and by zinc and copper 18. The resistance of the long wires diminishes, therefore, the quantity yielded by zinc and iron from 100 to 13, and by zinc and copper, from 100 to 18.-When the plates are connected by a fine wire 2000 feet long, the quantity of electricity yielded by zinc and iron is to that furnished by the zinc and copper as 1000: 1678. With amalgamated iron, zinc yields a much feebler current than with common iron. (Poggendorff.) Göttling (Gilb. 28, 475) constructed a powerful pile with plates of iron covered with zinc on one side, and moistened pieces of cloth. Cadmium is positive towards iron in dilute sulphuric acid, and yields 400 times more electricity than copper with platinum. Nevertheless, more iron than cadmium is dissolved. (Poggendorff.) [This deserves attention.] Tin is positive with lead in concentrated aqueous solution of oxalic or tartaric acid, negative in very dilute solutions. (Fechner.)-Tin is positive with iron or copper in dilute acid (De la Rive); and a steel wire consequently remains bright, and loses no weight, when placed in contact with tin under dilute hydrochloric acid. (J. Davy.) The following are the weights lost by tin balls of equal size placed for an hour in very dilute hydrochloric acid, contained-in vessels of different materials: in vessels of glass or sulphur, 3; of lead, 12; silver, 19; antimony, 34; bismuth, 36; copper, 70; platinum, 85; gold, 201. (Bouchardat.) Polished lead is positive in dilute acid towards iron and copper, tarnished lead negative. (Yorke.) In dilute hydrochloric or sulphuric acid, iron is, after the first moment, positive towards lead. (Wetzlar.) [Was the lead quite clean?].-Iron, when in contact with lead, dissolves more slowly in dilute sulphuric acid than when alone: after a few days, the iron becomes dull, and covered with sulphate of lead. In dilute hydro ic acid, on the contrary, the solution of iron is accelerated by contact both lead. (Runge.) In cold dilute sulphuric acid, tin is feebly positive towards lead; slightly negative, when the acid is warm. Towards iron, tin is positive in cold acid, often slightly negative in warm acid. (Faraday.) Antimony in dilute sulphuric acid is positive towards bismuth. (Fechner.) Iron in dilute acid is strongly positive towards arsenic. (De la Rive.) Nickel in dilute sulphuric acid is positive towards antimony and bismuth. (De la Rive.) Copper in dilute acids is positive towards silver and platinum; so also is silver towards platinum. (Walcker.) Gold exerts a scarcely perceptible positive reaction towards platinum in dilute sulphuric acid. (Ritchie.) In dilute sulphuric acid it is positive; in dilute hydrochloric acid, negative. (Walcker.)-In a mixture of 1 part oil of vitriol and 100 water, it is at first positive, then, after several immersions, neutral, and subsequently negative. (Marianini.) Palladium gives no current with platinum in pure hydrochloric acid, but becomes positive on the addition of nitric acid. (De la Rive.) Anthracite in dilute sulphuric or hydrochloric acid is negative towards copper, silver, or platinum. (Becquerel.) Platinum is at first positive towards graphite, neutral after several immersions, then negative. The graphite remains unaltered; but the platinum is rendered positive towards other platinum, losing this property, however, by ignition or immersion in boiling water. Gold and silver exhibit similar relations towards graphite, but in a lower degree. When platinum, gold, or silver is immersed in contact with graphite till it ceases to produce deflection of the needle, and then,-while still remaining in the acid-connected for a short time with zinc, it again becomes positive to graphite. Possibly, when these metals are placed in contact with graphite, a portion of oxygen becomes fixed upon them, and renders them more negative; and when they are connected with zinc, this oxygen is removed by the hydrogen, the latter then accumulating on the surface of the metal: for platinum which has been in contact with zinc under dilute acid is positive towards platinum which has not been so treated. (Marianini.) Platinum is feebly positive towards peroxide of manganese in dilute acid. (De la Rive). Pairs of plates of the same size of different metals immersed in very dilute sulphuric acid produce the following deflections of the needle: Zinc with lead 90°, with iron 6.3°, with copper 8.0°, with gold 6.0°, with platinum 3.3.-Tin with copper 5.0°, with silver 4.0°, with gold or platinum 1.0.-Lead with iron 20°, with copper 5.3°, with silver 4.3°, with gold 1.5°, with platinum 20°.-Iron with copper 30°, with gold or platinum 10°-Copper with silver 33, with gold or platinum 0·3°-Silver with gold or platinum 0.3°. The positive metal in each case has its name printed in italics.-These deflections are not in accordance with the theory of contact. The smallest deflections are those obtained with pairs containing gold or platinum;-it is true that platinum does not conduct so well as silver; but gold conducts better-and yet copper and silver give a stronger deflection than copper and gold. (Marianini.) Electrical series of perfect conductors in dilute acids, each body of the series being negative with those which precede, and positive with those which follow it: abundant as with copper, the size of the plates being the same in bot cases, so that a ten-pair battery of zinc and iron yields in seven minu (if the polar wires are made to dip into water) as much detonating cas a battery of zinc and copper of the same dimensions. But its only the quantity of the electric current that is greater in the case of zinc and iron; the tension is smaller. At the first moment of immersion, the quantity also is greater with zinc and copper; bnt the copper soon becomes covered with a dark film of oxide [sulphuret ?], while the iron remains clean, and this film interferes with the electrical conduction between the copper and the liquid. When a pair of zinc and iron plates, and a pair of zinc and copper, are left in action for twelve hours, the following loss of metal is observed: Copper, 0; zinc connected with it, 96 grains; iron, 6 grains; zinc connected with it, 74 grains. It appears, then, that a small quantity of iron is dissolved; and of the zinc connected with copper more than of the other zinc,--and yet the quantity of the current is greater with zinc and iron. [Hence, zinc and copper produce a greater amount of purely chemical action]. (Martyn Roberts, Phil. Mag. J. 16, 142; 19, 106.) Zinc and iron produce a more copious current than even zinc and silver or zinc and platinum, both in dilute sulphuric and dilute nitric acid; and the plates of the zinc and platinum pair must have a surface three times as great as that of the zinc and iron to yield the same quantity of electricity. But the intensity of the current excited by zinc and iron is smaller. If the quantity of electricity yielded by zinc and iron be 260, that yielded by zinc and copper is 100: when the plates are connected by a wire 50 feet long, the quantity yielded by zinc and iron is 337, and by zinc and copper 18. The resistance of the long wires diminishes, therefore, the quantity yielded by zine and iron from 100 to 13, and by zine and copper, from 100 to 18.-When the plates are connected by a fine wire 2000 feet long, the quantity of electricity yielded by zinc and iron is to that furnished by the zinc and copper as 1000: 1678. With amalgamated iron, zinc yields a much feebler current than with common iron. (Poggendorff.) Göttling (Gilb. 28, 475) constructed a powerful pile with plates of iron covered with zinc on one side, and moistened pieces of cloth. Cadmium is positive towards iron in dilute sulphuric acid, and yields 400 times more electricity than copper with platinum. Nevertheless, more iron than cadmium is dissolved. (Poggendorff.) [This deserves attention.] Tin is positive with lead in concentrated aqueous solution of oxalic or tartaric acid, negative in very dilute solutions. (Fechner.)-Tin is positive with iron or copper in dilute acid (De la Rive); and a steel wire consequently remains bright, and loses no weight, when placed in contact with tin under dilute hydrochloric acid. (J. Davy.) The following are the weights lost by tin balls of equal size placed for an hour in very dilute hydrochloric acid, contained-in vessels of different materials: in vessels of glass or sulphur, 3; of lead, 12; silver, 19; antimony, 34; bismuth, 36; copper, 70; platinum, 85; gold, 201. (Bouchardat.) Polished lead is positive in dilute acid towards iron and copper, tarnished lead negative. (Yorke.) In dilute hydrochloric or sulphuric acid, iron is, after the first moment, positive towards lead. (Wetzlar.) [Was the lead quite clean?].-Iron, when in contact with lead, dissolves more lowly in dilute sulphuric acid than when alone: after a few days, the iron becomes dull, and covered with sulphate of lead. In dilute hydro foric acid, on the contrary, the solution of iron is accelerated by contact Dofith lead. (Runge.) In cold dilute sulphuric acid, tin is feebly positive towards lead; sligholy negative, when the acid is warm. Towards iron, tin is positive in cold acid, often slightly negative in warm acid. (Faraday.) Antimony in dilute sulphuric acid is positive towards bismuth. (Fechner.) Iron in dilute acid is strongly positive towards arsenic. (De la Rive.) Nickel in dilute sulphuric acid is positive towards antimony and bismuth. (De la Rive.) Copper in dilute acids is positive towards silver and platinum; so also is silver towards platinum. (Walcker.) Gold exerts a scarcely perceptible positive reaction towards platinum in dilute sulphuric acid. (Ritchie.) In dilute sulphuric acid it is positive; in dilute hydrochloric acid, negative. (Walcker.)-In a mixture of 1 part oil of vitriol and 100 water, it is at first positive,-then, after several immersions, neutral, and subsequently negative. (Marianini.) Palladium gives no current with platinum in pure hydrochloric acid, but becomes positive on the addition of nitric acid. (De la Rive.) Anthracite in dilute sulphuric or hydrochloric acid is negative towards copper, silver, or platinum. (Becquerel.) Platinum is at first positive towards graphite, neutral after several immersions, then negative. The graphite remains unaltered; but the platinum is rendered positive towards other platinum, losing this property, however, by ignition or immersion in boiling water. Gold and silver exhibit similar relations towards graphite, but in a lower degree. When platinum, gold, or silver is immersed in contact with graphite till it ceases to produce deflection of the needle, and then,-while still remaining in the acid-connected for a short time with zinc, it again becomes positive to graphite. Possibly, when these metals are placed in contact with graphite, a portion of oxygen becomes fixed upon them, and renders them more negative; and when they are connected with zinc, this oxygen is removed by the hydrogen, the latter then accumulating on the surface of the metal: for platinum which has been in contact with zinc under dilute acid is positive towards platinum which has not been so treated. (Marianini.) Platinum is feebly positive towards peroxide of manganese in dilute acid. (De la Rive). Pairs of plates of the same size of different metals immersed in very dilute sulphuric acid produce the following deflections of the needle: Zinc with lead 90°, with iron 6.3°, with copper 80°, with gold 6.0°, with platinum 3.3.-Tin with copper 50°, with silver 4.0°, with gold or platinum 1.0°.-Lead with iron 20°, with copper 5.3°, with silver 4.3°, with gold 1.5°, with platinum 20°.-Iron with copper 30°, with gold or platinum 1.0°.-Copper with silver 33, with gold or platinum 0·3°.— Silver with gold or platinum 0·3°. The positive metal in each case has its name printed in italics.-These deflections are not in accordance with the theory of contact. The smallest deflections are those obtained with pairs containing gold or platinum;-it is true that platinum does not conduct so well as silver; but gold conducts better-and yet copper and silver give a stronger deflection than copper and gold. (Marianini.) Electrical series of perfect conductors in dilute acids,-each body of the series being negative with those which precede, and positive with those which follow it: According to Sir H. Davy: Potassium and its amalgam, barium and, its amalgam, zinc-amalgam, zinc, ammonium-amalgam, cadmium, tin, irov bismuth, antimony, lead, copper, silver, palladium, tellurium, gold, pl num, iridium, rhodium. Rolled copper is positive towards that wa contains carbon (overpoled); this towards the same metal conting suboxide (underpoled); and this towards copper containing tin. According to Faraday: In a mixture of one measure of oir vitriol with one measure of water: Zinc, cadmium, tin, lead, iron, nickebismuth, antimony, copper, silver. According to Pfaff: Zinc, cadmium, tin, lead, tungsten, on, bismuth, antimony, copper, silver, gold, tellurium, platinum, palladin. According to Marianini,-in very dilute sulphuric ad: Zinc, charcoal immediately after being cooled in water (containing hydrogen therefore) polished lead, tin, manganese, tarnished lead, inn, magnetic iron ore, brass, copper, brass very much corroded, bismuth, nickel, charcoal soon after being quenched in water, bright antimony, tinstone, native sulphuret of molybdenum, bright arsenic, tarnished antimony, silver, mercury, tarnished arsenic and arsenical silver, red silver, galena, freshly prepared charcoal, copper-nickel, copper-glance, arsenical cobalt, black tellurium, copper pyrites, platinum, gold, auriferous native tellurium, cubical iron pyrites, graphite, arsenical pyrites, magnetic pyrites, amorphous iron pyrites, peroxide of manganese, charcoal long exposed to the air. Experiments with Concentrated Hydrochloric Acid. Zinc gives with platinum a current which is feeble as long as the chemical action continues powerful, but becomes stronger as the chemical action diminishes. (Pfaff.) Tin is negative with lead at the beginning of the action, but afterwards becomes permanently positive, because the lead acquires a coating of chloride of lead.-Nickel is positive towards antimony and negative to bismuth. (Faraday.) In fuming hydrochloric acid, bismuth and copper are positive towards antimony: bismuth is first positive towards copper, and afterwards negative. (Fechner.) Platinum is very feebly positive towards gold in concentrated hydrochloric acid. (Walcker, Fechner.) When copper or silver is fastened to anthracite by means of a wire under strong hydrochloric acid, dichloride of copper in tetrahedrons or chloride of silver in transparent octohedrons, is after a time deposited on the metal which remains positive-while carburetted [?] hydrogen gas is evolved at the surface of the anthracite. (Becquerel.) Platinum is strongly positive towards peroxide of manganese, chlorine being evolved and chloride of manganese produced. Electrical series of metals in hydrochloric acid, according to Faraday: Zinc, cadmium, tin, lead, iron, copper, bismuth, nickel, silver, antimony. Experiments with Oil of Vitriol. In fuming sulphuric acid, zine is first negative towards lead, then neutral, then positive.-Zinc is negative to tin and remains so on moderate dilution of the acid; whereas fresh zinc in the same mixture would be positive towards tin:-zinc or tin is positive towards iron;-bismuth positive towards zinc, lead, or antimony; bismuth towards tin, first positive, then negative. (Fechner.) A pair of zinc and copper in oil of vitriol produces a current which, together with the accompanying development of gas on the zinc, soon ceases. Breaking the circuit does not restore the current: agitation on the surface of the zinc restores it partially; but a drop of water on the |