. Elementary chemical microscopy. Microscopy; Microchemistry. ILLUMINATION OF OBJECTS; ULTRA VIOLET LIGHT 49 not to the light rays resulting from the fluorescing of the sub- stance; the ultraviolet rays, however, readily penetrate quartz. We have, therefore, only to substitute quartz for glass in the condenser in order to concentrate the ultra rays on the object upon the stage. It follows from this that although the illu- minating devices must be of quartz, as also the object slide upon which the object lies, the objective and ocular may be those ordinarily employed. Either a carbon arc with s
. Elementary chemical microscopy. Microscopy; Microchemistry. ILLUMINATION OF OBJECTS; ULTRA VIOLET LIGHT 49 not to the light rays resulting from the fluorescing of the sub- stance; the ultraviolet rays, however, readily penetrate quartz. We have, therefore, only to substitute quartz for glass in the condenser in order to concentrate the ultra rays on the object upon the stage. It follows from this that although the illu- minating devices must be of quartz, as also the object slide upon which the object lies, the objective and ocular may be those ordinarily employed. Either a carbon arc with special carbons or a mercury vapor lamp may be employed as radiant. Fig. 21 shows diagrammatically the construction of a fluores- cence microscope. The rays from the radiant R are concen- trated by the quartz condensing lens Q. then pass through the Wood-Lehmann filter F consisting of a quartz or of a blue " Uviol " glass cell, thence the rays pass to the reflecting quartz prism P which in turn reflects them into the ( quartz lens dark- ground condenser. This device brings the ultraviolet rays to a focus upon the object supported upon the stage by means of an object slide of quartz or of Uviol glass. Ordinary glass, besides being practic- ally opaque to rays of very short wave-length, as stated above, fluoresces with a violet or bluish tint under the action of the ultraviolet rays and cannot therefore be employed as a support. If it is necessary to cover the preparation ordinary glass cover- glasses may be employed, but glass should never be used if thin quartz cover-glasses are available. As in all dark-ground illuminators, an immersion fluid between condenser and object slide is essential. In this case glycerine is employed (n = ). The light filter whose function is the removal of waves of long wave-length, affecting the eye as light, consists of two com- partments, one filled with a 20 per cent copper sulphate solution, I. Fig. 21. Reichert Fluorescence Microsco
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