476 INDEX 



PAGE 



Oculars, care of I5 



comparison 24 



compensating j^ 



cross-haired 55 



goniometer j cj 



Huygens I2 



micrometer ig! 



negative 12 



net ruled 202 



par focal 15 



positive 12 



projection I5 



Ramsden 12 



Oil globules, optic behavior of 229 



Optic axes of crystals 254 



axial angles 257 



Optics of compound microscope I 



Ordinary ray , 52 



Orientating devices 141 



Orthogonal illumination 47 



Orthorhombic system, characteristics of 268 



Oxalates, detection of 427 



Paint films, examination of 196 



Paper fibers --..456,457 



Parallel extinction 253 



Paraboloid dark-ground illumination 36 



Penetrating power of objectives 8 



Periodic system of Mendelejeff 446 



Petrographic microscopes 75 



Phosphates, detection of 427 



Platinum cups 296 



wires 148 



Pleochroism 263 



Polarizer. 53 



Polarization colors 260 



tube 166 



Polarized light 50 



Polishing 436 



Polymorphous crystals 251 



Potassium, common salts .' 327 



detection by chloroplatinic acid 327 



perchloric acid 330 



mercuric thiocyanate, preparation of 450 



Prism vertical illuminators 77 



Projected image scale in quantitative work 206 



Pseudomorphs 251 



