+-----------------------------+----------+----------+ | TEMPERATURE | WATER | TOLUOL | +-----------------------------+----------+----------+ | Centigrade | Fahrenheit | | | | | | | | | 14° | 57·2° | 0·9994 | 0·8697 | | 15° | 59·0° | 0·9992 | 0·8687 | | 16° | 60·8° | 0·9990 | 0·8677 | | 17° | 62·6° | 0·9988 | 0·8667 | | 18° | 64·4° | 0·9986 | 0·8657 | | 19° | 66·2° | 0·9985 | 0·8647 | | 20° | 68·0° | 0·9983 | 0·8637 | | 21° | 69·0° | 0·9981 | 0·8627 | | 22° | 71·6° | 0·9979 | 0·8617 | | 23° | 73·4° | 0·9977 | 0·8607 | +-----------------------------+----------+----------+ 1 English carat = 0·2053 gram 1 Metric carat = 0·2000 (one-fifth) gram 1 oz. Av. = 28·35 grams 1 lb. Av. = 0·4536 kilogram 1 inch = 25·4 millimetres 1 foot = 0·3048 metre 1 yard = 0·9144 metre 1 mile = 1·6093 kilometre INDEX Absorption, 53, 59 Absorption spectra, 59 Achroite, 220, 221 Adularia, 255 Agate, 247 Akbar Shah diamond, 163 Alalite, 272 Albite, 254 Alexandrite, 54, 60, 233 Scientific, 122 Almandine, 60, 214 Oriental, 112, 172 spinel, 112, 204 Amazon-stone, 255 Amber, 83, 298 Amethyst, 239, 242 Oriental, 111, 172, 239 Anatase, 281 Andalusite, 274 Andradite, 216 Anomalous refraction, 47 Anorthite, 254 Apatite, 279 Apophyllite, 290 Aquamarine, 184, 193 Arizona-ruby, 213 Artificial stones, 124 Asteria, 38, 177 Asterism, 38 Australia stones, 154, 174, 182, 195, 213, 216, 227, 232, 252, 288 Austrian Yellow diamond, 165 Aventurine, 240, 241 Axes, Crystallographic, 9 Optic, 49 Axinite, 278 Azure-quartz, 244 Azurite, 287 Balas-ruby, 203 Barnato, Barnett, 145 Baroque, Barrok, pearls, 292 Bastite, 272 Benitoite, 267 Berquem, Louis de, 90, 161 Beryl, 184 Beryllonite, 270 Bezel facet, 92 Biaxial double refraction, 45, 49, 57 Bisectrix, 45, 49 Black diamond, 129 Black lead, 129 Black opal, 249, 250 Black Prince’s ruby, 206 Blister-pearl, 296 Bloodstone, 247 Blue felspar, 255 Blue ground, 143, 147 Blue John, 285 Boart, 103, 129, 133 Bohemian garnet (pyrope), 207, 212 Bone turquoise, 259