Intelligence and Miscellaneous Articles. 245 



paratus by which even small heating -effects could be recognized with 

 certainty. The result of the experiments made therewith quite an- 

 swered my expectations. The construction of the apparatus is as fol- 

 lows : — I covered with silk a fine iron and equally fine German-silver 

 wire. These wires were cut into pieces about a decimetre in length, 

 and each German-silver wire soldered to an iron wire. These wires 

 were so laid upon a glass plate covered with a cement of resin and 

 shell-lac, that the solderings of 180 wires, without touching, occupied 

 a space of about a square decimetre. By pressing with a warm iron 

 the wires were fused into the cement and thus fastened upon the plate. 

 After the adjacent free ends of the wires were soldered together so 

 as to form a battery of 180 elements, a second glass plate, also covered 

 with cement, was laid with the cemented surface upon the first. By 

 careful heating, the cement between the glass plates was softened, 

 and a portion of it, with the individual air-bubbles which it enclosed, 

 pressed out. The thermo-pile stood thus in a surface of cement 

 free from air, exactly in the middle of a glass plate about 5 millims. 

 in thickness. The middle of the glass plates covering thus all the 

 inside solderings was provided on both sides with tinfoil armatures 

 about a decimetre square, which were furnished with insulated wires. 

 'J he free ends of the thermo-pile were also furnished with copper 

 wires, by which they were connected with a delicate reflecting galva- 

 nometer. The entire apparatus, including the external solderings, was 

 carefully protected from any change of temperature. A short succes- 

 sion of charges and discharges, by means of a voltaic inductor of about 

 an inch striking- distance, was sufficient to drive the scale of my gal- 

 vanometer out of the field, and this, too, in the direction due to the 

 heating of the solderings between the armatures. After the charges 

 the deflection returns very slowly to zero. It disappears entirely 

 only after some hours. It is independent of the direction of the dis- 

 charge, and apparently proportional to the number of charges, and 

 to the striking-distance to which the apparatus was charged. The 

 motion of the scale begins at once, and then proceeds regularly. But 

 if one of the armatures be touched with the finger, the scale remains 

 stationary two or three seconds before beginning its motion, which 

 usually terminates outside the field of view. 



The heating-effect observed can be due neither to conduction 

 through the mass of glass, nor to compression by attraction of the 

 armatures, nor, finally, to penetration of electricity into the glass-mass 

 nearest the armatures. The first objection is directly answered by 

 the arrangement of the apparatus and the experiments described. 

 Any heating by compression would be equalized by the subsequently 

 equally strong cooling on expansion, and could therefore produce no 

 permanent heating, even if the extremely small contraction were suffi- 

 cient. Nor could a penetration of electricity into the mass of glass 

 nearest the coatings be the cause of the heating, as the deflection did 

 not begin at once, but only after the lapse of some seconds. But if 

 we assume, with Mr. Faraday, that the charge and discharge depends 

 on a progressive molecular motion in the insulator which separates 

 the coatings, the fact of the heating of this insulator is no longer 

 surprising. — Berliner Berichte, 1864, p. 612. 



