254 



EXHIBITION OF ELECTRICITY AT PARIS. 



differs from that of the Gramme machine in be- 

 ing divided into eight parts, ivu-h of the eight 

 narrow rings, which are hexagonal, is wound 

 with wire, each side of the hexagon serving as 

 a bobbin. This allows the corners of the hexa- 

 gon to approach more nearly to the field-mag- 

 nets, increasing the induction. The corners 

 are not placed opposite each other, but each 

 ring is carried a little farther around the axle 

 than the next, so that the current is derived 

 from the forty-eight bobbins in succession. A 

 new form of Gramme machine, devised for the 

 Jabloehkotf and similar lamps, which require 

 alternating currents in opposite directions, acts 

 as its own exciter, instead of requiring a sepa- 

 rate machine as formerly. The Weston ma- 

 chine resembles a Siemens machine, with field- 

 magnets of the Gramme type. The metal strips 

 of the commutator are twisted spirally. 



The improvement of Plante's secondary bat- 

 tery by Faure has occupied the attention of 

 electricians more than any other recent inven- 

 tion, on account of the important useful appli- 

 cations which may be found for a device which 

 stores up electric energy and gives it out again 

 whenever needed in a moderate quantitative 

 current. The condensing battery of Faure has 

 already been applied to useful purposes, such 

 as electric lighting, but its economy and utility 

 are thus far the subjects of theoretical conclu- 

 sions principally. A Faure apparatus weigh- 

 ing one hundred and forty pounds can store 

 up energy which can be converted into one 

 horse-power of mechanical work continuing 

 for one hour. 



Secondary batteries of this type have been 

 made before by Plante and by Ritter, a Ger- 

 man electrician. Plant6 improved upon Rit- 

 ter's plan by employing lead for the plates. 

 The earliest form of a secondary battery was 

 proposed by Grove in 1841. The principle of 

 a secondary battery is to accomplish a chemical 

 separation by the electrolytic action of the vol- 

 taic current of the constituents of a substance, 

 which in reuniting convert into electricity 

 again the energy which had been stored up by 

 the chemical work in a static form. Grove 

 made such a battery by electrically decompos- 

 ing water. A continuous current was evolved 

 by the spontaneous recombination of the hy- 

 drogen and oxygen, but it was exceedingly fee- 

 ble on account of the limited surface of triple 

 contact between the platinum, the acidulated 

 water, and the gas. Dr. Siemens contrived a 

 gas-battery in 1852, iti which greater surfaces 

 of contact were obtained, and a current of 

 considerable power was produced. He used 

 carbon tubes coatad with platinum powder. 

 With peroxide of lead instead of platinum bet- 

 ter results were obtained and the cost of the 

 apparatus reduced. Plante obtained greater 

 surface and a larger current by rolling two 

 lead plates into a spiral form and separating 

 them by an insulating material. By a peculiar 

 process of preparing the plates he increased 

 the duration of the current. Faure has done 



away with this long and elaborate process of 

 formation, and has greatly increased the capa- 

 city of the secondary battery. In all secondary 

 batteries the voltaic current produces a chem- 

 ical change in the plates, which in returning 

 to their original condition generate a current. 

 The material agents by which the storing of 



THE FAURE EATTEKY. 



electric force takes place in Faure's cell are lead, 

 and red-lead or minium. Red-lead is a mixt- 

 ure of equal parts of the protoxide and the 

 sesquioxide of lead. It is formed by passing a 

 current of air over metallic lead at a tempera- 

 ture of 700 Fahr. The sesquioxide in its com- 

 position is prone under proper conditions to 

 part with its excess of oxygen, and will be 

 largely converted into the protoxide at a red 

 heat ; while the lower oxide has a tendency to 

 take up more oxygen. Faure's battery consists 

 of two plates of lead coated with red oxide, cov- 

 ered with porous felt, and rolled up into a spi- 

 ral scroll. Two scrolls are placed side by side 

 in a vessel of acidulated water, with a strip of 

 lead projecting from each by which a circuit 

 connection with a battery can be established. 

 When the circuit connection is made with the 

 poles of a galvanic battery or a dynamo-ma- 

 chine, the voltaic current causes a chemical 

 action to take place. The red-lead on the spi- 

 ral plate which is joined to the positive elec- 

 trode becomes gradually more highly charged 

 with oxygen and is converted into the perox- 

 ide of the metal, while the oxides on the plate 

 connected with the negative pole gradually part 

 with their oxygen and are reduced to the state 

 of spongy, metallic lead. When the battery is 

 charged that is, when the red-lead is deoxi- 

 dized on one plate and converted into the high- 

 est oxide on the other the plates can be dis- 

 connected from the charging battery, and the 

 chemical work which has been accomplished 



