XX CONTENTS 



49O 



49 1 

 492 



493 



494 



Allowable carrying capacity of rubber-covered copper wires . . . 416 



Resistivities at high and low temperatures 417 



Volume and surface resistivity of solid dielectrics 418 



Variation of resistance, glass and porcelain, with temperature . . . 419 



Temperature resistance coefficients of glass, porcelain, and quartz . 419 



Wire Tables 



495. Tabular comparison of wire gages 420 



496. Introduction; mass and volume resistivity of copper and aluminum. 421 



497. Copper wire : Temperature coefficients 422 



498. Reduction of observations to standard temperature. 422 



499. " , standard annealed : English units, B. & S. gage . . 423 



500. " " " " Metric " " " . . 426 



501. Aluminum wire, hard-drawn: English units, B. & S. gage .... 429 



502. " " " " Metric " " " . . . . 430 



Electrolysis 



503. Electrochemical equivalents 431 



504. Conductivity of electrolytic solutions 432 



505. Electrochemical equivalents and normal solutions 432 



506. Specific molecular conductivity of solutions : Mercury=io 8 . . . 433 



507. Limiting values of /*. 434 



508. " " " Temperature coeffici- 

 ents 434 



509. Equivalent conductivity of salts, acids, bases in aqueous solutions . 435 



510. " additional salts in aqueous solutions . . 437 



511. " separate ions 438 



512. Hydrolysis of ammonium acetate and ionization of water .... 438 



Dielectric Strength 



513. Steady potential required to produce spark in air, ball electrodes . 439 



514. A.c. " " << " " " " " " . 439 



515. Potential to produce spark in air, more widely separated electrodes. 440 



516. Effect of the pressure of the gas on the dielectric strength .... 440 



517. Dielectric strength of materials 441 



518. Potentials in volts to produce a spark in kerosene 441 



Dielectric Constants 



519. Dielectric constant of gases : Atmospheric pressure 442 



520. " " , temperature variation 442 



521. " " pressure variation 442 



522. " " liquids (e). Pressure effect 443 



523. " " " " 443 



