HTSTOEY, (fee, OF INDUCTION INSTRUMENTS. 



303 



£ lt,Sli£iiir, 



Fig. 86.— Gaifle's apparatus. 



tained in a cell of hard caoutchouc, at the bottom of which are 

 fixed two plates of gas-carbon. The platinum wires that establish 

 the communication are imbedded in the mass, and project beyond 

 it ; the two zinc plates lie flat in the place prepared for them ; 

 and the apparatus requires nothing beyond the establishment of 

 the communications, — nothing can be more easy of manipulation. 



" The apparatus furnishes the extra current, the induced cur- 

 rent, and, if needed, the combination of the two. The communi- 

 cations are easy to make : since M. Gaifife has taken the precaution 

 to mark the direction of the currents uj)on the binding-screws 

 that receive the conductors to the rheophores, 



" In the figure, L is the small cell of caoutchouc, containing the 

 two elements of the battery. K, a tube containing a jarovision of 

 bisulphate of mercury ; M, induction coil ; R, knob of the gra- 

 duator tube ; 0, Q, pieces of the trembler ; P, knob that is pressed 

 upon to produce isolated interruptions; N, cylinders; T, various 

 exciters. 



New-Pattern cMoride of silver hattery. — " M. Gaiffe has ar- 

 ranged a new pattern, the felicitous combination of which practi- 

 tioners will not fail to appreciate. He has been stimulated by the 

 example of M. Trouve, whose hermetically sealed pile will pre- 

 sently be described ; but he has known how to avail himself of 

 the valuable properties of the fused chloride of silver,^ to which 

 Mr. Warren de la Rue has recently called attention. Each of the 

 elements of the battery contained in Gaiffe's apparatus is composed 



" A battery of salt water, chloride of 

 silver, and iron or zinc, had been em- 

 ployed, nearly thirty years ago, by M. 

 Becquerel, in his researches upon the 

 electro-chemical treatment of the ores of 

 silver 'Seu Beciuerel and E. Becquerel, 

 Traite d'eicctricite, tom. ii. Paris, 1855). 

 M. Marie'-Davy has constructed a battery 

 of zinc, pure water, and fused chloride of 

 silver ( Comptes renchis de VAcademie 

 des Sciences, tom. xlix., 1S59;. M. E. 



Becquerel (M^moire sur la pile toltaique 

 in Annales du Conservatoire des arts et 

 me'tiers, tom. i., p. 295, 1861 j has deter- 

 mined the electru-iuotor force of a pair in 

 which the depolarization of the negative 

 electrode was obtained by precipitated 

 chloride of silver placed upon a diajjhragm 

 of the battery. He found it a little in- 

 ferior to that of a pair with sulphate of 

 copper ; that is to say, very little more 

 than half that of a j^air with nitric acid. 



