Xl CONTENTS. 



255. Dielectric strength ; steady potential for spark in air . . . .248 



256. " " alternating potential for spark in air . . . 248 



257. " potentials for longer sparks in air ... 249 



258. " " effect of (air) pressure ...... 249 



259. " " of various materials . . , . . . 250 



260. " " u kerosene . ...... 250 



261. Electromotive force of standard cells : absolute current measures . 251 



262. Data for voltaic cells : (a) double fluid cells 252 



(b) single fluid cells ..... 253 



(c) standard cells ...... 253 



(d) secondary (storage) cells .... 253 



263. Contact differences of potential, solids with liquids and liquids with 



liquids in air 254 



264. Contact differences of potential, solids with solids in air . . 256 



265. Potential difference between metals in various salt solutions . . 257 



266. Thermoelectric powers ......... 258 



267. " " with platinum 259 



268. Peltier effect 260 



269. Various determinations of the ohm 261 



270. Specific resistance of metallic wires ....... 262 



271. " " " metals 263 



272. Resistance of metals and alloys at low temperatures . . . .264 



273. Conductivity of three-metal and miscellaneous alloys .... 266 



274. Conducting power of alloys 267 



275. Electric resistance with alternating currents (straight wires) . . 269 



276. International atomic weights and electrochemical equivalents . . 270 



277. Conductivity of a few dilute solutions 272 



278. Electrochemical equivalents and densities of nearly normal solutions . 272 



279. Specific molecular conductivity of solutions . . . . . . 273 



280. " " " " " limiting values . . . 274 



281. " " " " " temperature coefficients . 274 



282. Equivalent conductivity of salts, acids, bases in solution . . . 275 



283. " " " some additional salts in solution . -277 



284. " conductance of the separate ions 278 



285. Hydrolysis of ammonium acetate : ionization of water . . . .278 



286. Dielectric constants (specific inductive capacity) of gases . . -279 



287. " " " " " " " temperature 

 coefficient 279 



288. Dielectric constants (specific inductive capacity) of gases : pressure co- 



efficient ............ 279 



289. Dielectric constants of liquids ^ . 280 



290. " " " " temperature coefficient .... 282 



291. " " liquefied gases 282 



292. " " standard solutions for calibrations . . . 283 



293. Dielectric constants of solids 283 



294. " " " crystals 284 



295. Temperature variation of electrical resistance of glass, porcelain . . 285 



296. Permeability of iron rings and wire, various inductions . . . 286 



