CONTENTS. Xlii 



294. Data for voltaic cells : (d) secondary (storage) cells .... 263 



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



liquids in air . . . . . . . . . . 264 



296. Contact differences of potential, solids with solids in air . . 266 



297. Potential difference between metals in various salt solutions . . 267 



298. Thermoelectric powers . ." . . . . . . . 268 



299. " " with alloys . . . . . . . 269 



300. " " platinum . . . . . .270 



301. " " of Pt. with Pt. Rh. alloys . . . .270 



302. Peltier effect . . . . . . . . . . .271 



303. " " Fe-constantan, Cu-constantan . . . . . .271 



304. " " E. M. F. in volts 271 



305. Various determinations of the ohm ....... 272 



306. Specific resistance of metallic wires 273 



307. Specific resistance of metals 274 



308. Temperature resistance coefficient 276 



309. Conductivities of three-metal and other alloys 277 



310. " " alloys 278 



311. Allowable carrying capacity rubber-covered copper wires . . . 279 



312. Resistance of metals and alloys at low temperatures .... 280 



313. Temperature variation of electrical resistance of glass, porcelain . . 282 



314. Temperature resistance coefficients of glass, porcelain, quartz . .282 



315. Tabular comparison of wire gages 283 



316. Wire tables. Mass and volume resistivities of Cu. and Al. . . 284 



317. " " Temperature coefficients of copper .... 285 



318. " " Reduction to standard temperatures .... 285 



319. Standard annealed copper wire, English units . . 286 



320. " " " " " " metric units . . 289 



321. Hand-drawn aluminum wire, English units . . . 292 



322. " " " " " " metric units . . 293 



323. Dielectric strength ; steady potential for spark in air .... 294 



324. " " alternating potential for spark in air . ' . . 294 



325. " " potentials for longer sparks in air ... 295 



326. " " effect of (air) pressure 295 



327. " " of various materials 296 



328. " " " kerosene 296 



329. Electric resistance with alternating currents (straight wires) . . 297 



330. " " for high frequencies 297 



331. Wireless telegraphy ; wave-lengths, frequencies, oscillation constant . 298 



332. " " radiation resistance for various wave-lengths . 300 



333. International atomic weights and electrochemical equivalents . .. 301 



334. Conductivity of a few dilute solutions 302 



335. Electrochemical equivalents and densities of nearly normal solutions . 302 



336. Specific molecular conductivity of solutions ..... 303 



337. " " " " " limiting values . . 304 



338. " " " " " temperature coefficients . 304 



