. The American journal of tropical medicine. was found to contain gram of extractives per 100 cc. FLUORESCENCE This yellow alcoholic solution did not possess any obviousfluorescence in ordinary light. In determining fluorescenceone encounters the difficulty of differentiating this phenomenon 118 D. M. GAY AND M. A. McIVER from the Tyndale effect due to fine particles in suspension. L. Chaffee of the Department of Physics kindly suggested thefollowing plan and provided specially tested color screens nec-essary for carrying it out. A small oblong box (12 by 6 by 4inches) with black inn
. The American journal of tropical medicine. was found to contain gram of extractives per 100 cc. FLUORESCENCE This yellow alcoholic solution did not possess any obviousfluorescence in ordinary light. In determining fluorescenceone encounters the difficulty of differentiating this phenomenon 118 D. M. GAY AND M. A. McIVER from the Tyndale effect due to fine particles in suspension. L. Chaffee of the Department of Physics kindly suggested thefollowing plan and provided specially tested color screens nec-essary for carrying it out. A small oblong box (12 by 6 by 4inches) with black inner walls is constructed with a partition4 inches from one end. Three apertures are provided, a slit,A ( inch) is cut in the side of the box to admit light into thesmall compartment, a similar sht, B, is cut in the center of thepartition, and a wide opening, C (3 by 3 inches) is made in theend of the large compartment for the convenience of the access to the small compartment is gained by means of alightproof hinged Fig. 1 The solution to be tested is placed in the small compartmentin front of the slit, B, illuminated through A, by colored hght,for example by a beam from an arc light, passing through a blueglass. If eosin is illuminated by a blue beam, the observer willsee a bright green light emitted from the red solution. Thischange in color of the light from blue to green affords virtualproof of fluorescence. Further confirmation of fluorescencemay be obtained in the following manner: A combination ofglasses is selected such as blue and red which when placed oneon top of the other do not permit any visible light waves to passthrough them. Then with the blue glass at aperture A, if the PHOTODYNAMIC ACTION OF EXTKACTS OF GRAINS 119 solution under investigation is still visible through the red glassat the opening, C, this means that fluorescence is occurring sincethe original blue light can not pass through the red glass. Thisapparatus proved satisfacto
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttropica, bookyear1921
