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acid aniline apparatus arrangement artist base board beautiful blue bottle bromide bromide paper brush camera Canada balsam carrier chloride plate clouds colours condenser consists cylinder described diagram disc effect employed emulsion enlarged exhibit experiment exposure ferrous oxalate film fitted focus focussing frame front galvanometer gelatine gelatine plate give glass groove hydrogen inches instrument Italian pink lamp lantern slides lantern stage lecture lens lenses light lime limelight manganese matter means ment method microscope necessary negative objective objective lens obtained once opaque operator optical lantern ordinary oxygen painting paper persistence of vision photographic piece placed position prism produce Prussian blue purpose quarter-plate readily retina retort Rose Madder screen screw seen sheet side slide-painter solution spectrum surface tank theory of colour tint transparent tube turpentine varnish wash wire worker yellow zinc
Page 75 - ... times the intensity of the brightest part of the flame of an Argand burner of the best construction, and supplied with the finest oil.
Page 231 - ... whatever upon the ice. But the liquefaction is not uniformly diffused. From separate spots of the ice little shining points are seen to sparkle forth. Every one of those points is surrounded by a beautiful liquid flower with six petals. " Ice and water are so optically alike that unless the light fall properly upon these flowers, you cannot see them.
Page 112 - ... about the middle; then reverse it again, and move it in several directions to get the balsam level. This may be done with a very little practice so that the surface shall be undistinguishable from glass. We have now a perfect transparency. All that is required is twenty-four hours for hardening (keeping the glass level), and then another square of glass fastened on to it by strips of paper at the edges, with small pieces of card at the corners to prevent contact, and it makes an admirable lantern...