PHYSICS. Gil 



force, with a saturated solution of potassium or sodium carbonate, on 

 open circuit, is 0.10 to 0.17 Daniell. With saturated solution sodium 

 hypochlorite, it rises to 0.4 to 0.5 Daniell. With graphite or wood char- 

 coal, the electromotive force is less. The circuit being closed, the carbon 

 disintegrates and produces oxidation compounds, the formation of which 

 is attended with an evolution of heat. (II Nuovo Cimento, III, xn, 141; 

 J. Phys., December, 1883, II, n, 570.) 



Two new forms of iufluence-machines have been produced, the one 

 by Voss, the other by Wimshurst. In the former there is a fixed disk 

 with quadrantal armatures, and a revolving disk with six or eight equi- 

 distant metallic buttons on the face, to act as carriers. In the latter 

 there are two revolving disks moving oppositely, each armed with 12: 

 radial sectors. Both machines are self-charging. (Nature, May, 1883, 

 xxvni, 12.) 



Elster and Geitel have proposed to string the disks of a dry pile upon 

 a silk thread in place of putting them in a glass tube. They find that 

 these dry piles may act as accumulators, and on charging a pile of 11,000 

 pairs of plates of a square centimeter surface with a Holtz machine it 

 gave sparks a millimeter long. A form of pile was made consisting of 

 7,000 plates of thin lead coated on both sides with tissue paper made to 

 adhere by water-glass to which a little lead peroxide was added. After 

 charging, this pile gave sparks one millimeter long for ten minutes, 

 and after twenty-four hours it still showed electrification. ( Wied. Ann., 

 xvn, 489 ; Phil. Mag., V, xvi, 159; Nature, July, 1883, xxvni, 234.) 



Eeynier has published some figures concerning the work done by a 

 Leclanche battery when used on a telephone exchange. Two batteries 

 of three cells each were used for thirty days of seven hours' duration. 

 The loss of weight of zinc during that time was 64.5 grams, which rep- 

 resents 63,235 coulombs. This is equal to a current of 0.084 amperes 

 during the month. Taking the electromotive force of a Leclanche' cell 

 as one volt, the total work done is 189,705 watts, which is equivalent to 

 a horse-power every fifty-two minutes. (Nature, July, 1883, xxvni, 

 309.) 



Wright and Thompson have investigated the Clark standard cell, 

 determining its electromotive force, the influence exerted upon this by 

 dissolved air, by contamination of the mercurous with mercuric sul- 

 phate, by time and by temperature changes. They conclude that Clark's 

 valuation for the electromotive force is exact, viz, 1.457 volts at 15°.5C. 

 These authors have also determined experimentally the work done in 

 the electrolysis of various solutions. (Phil. Mag., July, 1883, V, xvi, 

 25.) 



Trouve' has experimented on the use of the bichromate battery for 

 incandescent lighting, and finds that 12 of his cells in two series of six 

 each maintained ten 10-volt lamps at 10 candles for two hours, the 

 electromotive force being 12.6 volts and the current 65 amperes. After 

 3 hours the current fell to 31.50 amperes, only 8 lamps being in circuit. 



