. Journal of applied microscopy and laboratory methods. g off at the violet end beforeH,. Group V—This group mostnearly approaches perfection. Itis characterized by a sensitiveband well below line D, andsomewhat below the red end ofGroups III and IV. This plategives an almost uniform degreeof sensitiveness with a maximumintensity in the green. If sensitiveness to the spec- and Laboratory Methods. 1491 trum were the only feature to be considered in the selection of a plate for photo-micrographic work, a plate from Group V would be chosen, but the generalworking of the plate as well as the keepi
. Journal of applied microscopy and laboratory methods. g off at the violet end beforeH,. Group V—This group mostnearly approaches perfection. Itis characterized by a sensitiveband well below line D, andsomewhat below the red end ofGroups III and IV. This plategives an almost uniform degreeof sensitiveness with a maximumintensity in the green. If sensitiveness to the spec- and Laboratory Methods. 1491 trum were the only feature to be considered in the selection of a plate for photo-micrographic work, a plate from Group V would be chosen, but the generalworking of the plate as well as the keeping qualities are factors that must beconsidered. For practical work and keeping qualities the author found theCadett & Neal Special Slow Spectrum Plate of Group IV most satisfactory, andused it in the preparation of the spectrographs illustrated in Fig. 3. Electric arc. - -Picric acid. - -Aurantia. - - -Cresoidin. - - -Congo Red. - -Eosin. - - - -Carbol ;Eniatoxylin. -INIethylen Blue. -Green Glass. - -Methyl Green. -Quinine Methylen Blue. Methyl Fuchsin. Fig. 3. Explanation to Plate.—This plate is a reproduction of spectrographic analyses of some of the commonstains. The red end of the spectrum is on the left. The principal Fraunhofers lines are name of the stain is on the left, while on the right is the name of the proper screen to use toincrease the photographic intensity. To decrease the contrast use a screen of the same color as thestain. The perfect photo-micrographic plate would give equal photographic in-tensity to all the colors of the visual spectrum, but since this degree of excellencehas not been attained, the value of a given plate may be enhanced by the use ofcolor screens, or ray filters, which serve to increase or decrease the photographicintensity of a color. The following are the laws upon which the use of colorscreens is based: First. To increase the photographic intensity
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
