Show lenses of spectrograph must be made of quartz the spectrograph is fin an optical in strument ment which splits spills up light into its constituent colors white light us as newton showed long asu ago Is a mixture ture of colors iolet andt irollo 0 o mini blue gren gre n yellow orange and red and n nd the he spectrograph tro trog graph breaks up ulo the suns stills rays into these Nv tints in that order the prisms and lenses of this inspru ment says a writer in its mag II 11 IK allne must all he be of quartz as glas gin will not allow the ultra reil red rays anys to pass cleves of quartz suitable for this delicate work are very expensive as out of many tons of this mineral few pieces are suitable newton only knew what he could see but the camera sees much more a ranke range of color hidden from vie tie titi I 1 man eye chemists working on dyes make use of the fact that a small alteration in the molecular groult ing of a dye causes a bis big change of color which means that the absorption of light by dye Is due to chemical ture I 1 in the same way analysis with rays beyond the violet we see named ultra i violet rays show that many sub stances colorless to the eye actually absorb netra idolet light ant and tile the precise measurement of this absorption helps to solve the problem of their chemical structure I 1 |