CONTENTS. XV 



314. Standards: International secondary Fe arc standards, Angstroms . . 266 



315. International secondary Fe arc standards, Angstroms . . 266 



316. Neon wave-lengths 266 



317. International tertiary Fe arc standards, Angstroms . . . 267 



318. Reduction of wave-lengths in air to standard conditions: 268 



(a) (d - do)/d X 1000; B, 60 to 78 cm, /, 9 to 35 C .... 268 



(b) 6 = AoOo- no')(d-do)/(k 268 



319. Spectra of the elements 269 



320. Spectrum lines of the elements (Kayser) '270 



321. Standard solar wave-lengths (Rowland) 272 



322. Spectrum series, general discussion 275 



323. " limits of some of the series 276 



324. " first terms and vibration differences 276 



INDICES OF REFRACTION 



325. Indices of refraction of glass (American) 277 



326. Dispersion of glasses of Table 325 277 



327. Indices of refraction of glasses made by Schott and Gen, Jena . ... 278 



328. Dispersion of Jena glasses 278 



329. Changes of indices for i C change for some Jena glasses 278 



330. Index of refraction of rock-salt in air 279 



331. Change of indices for i C change for rock-salt 279 



332. Index of refraction of silvine (potassium chloride) in air 279 



333. " " " " fluorite in air 280 



334. Change of indices for i C change for fluorite 280 



335. Index of refraction of iceland spar (CaCOs) in air 280 



336. " " " nitroso-dimethyl-aniline 280 



337. " " " quartz (SiO 2 ) 281 



338. Indices of refraction for various alums 281 



339. " " refraction: Selected isotropic minerals 282 



340. Miscellaneous isotropic solids 283 



341. Selected uniaxial minerals (positive) 284 



(negative) 284 



342. Miscellaneous uniaxial crystals 285 



343. Selected biaxial minerals (a) positive 286 



(b) negative .... 287 



344. Miscellaneous biaxial crystals 289 



345. Liquefied gases, oils, fats, waxes 289 



346. Liquids relative to air 290 



347. Solutions of salts and acids relative to air . . 291 



348. Gases and vapors 292 



349. Air, 15 C, 76 cm; also corrections for reduc- 

 ing wave-lengths and frequencies in air to vacuo (see Table 318) . 293 



350. Media for microscopic determinations of refractive indices: liquids 



with ^0(0.589)11) = 1.74 to 1.87 294 



