. Journal of applied microscopy and laboratory methods. if it was due to areflection from some interior surface, and it mightbe assumed that the diffusion was due to this sur-face not being perfectly smooth. In order to findthe angle between the supposed interior surface ofreflection and the surface of the section, Let O be center of revolution, Let C be collimator. Let T be telescope. Let N be normal to plate when yielding ordi-nary signal, Let N^ be normal to plate when yieldingschiller signal. If COTr=2 cp then CON^TON^^y and, see Fig., a=(^—e and b=+ as the rays from C and to T must h
. Journal of applied microscopy and laboratory methods. if it was due to areflection from some interior surface, and it mightbe assumed that the diffusion was due to this sur-face not being perfectly smooth. In order to findthe angle between the supposed interior surface ofreflection and the surface of the section, Let O be center of revolution, Let C be collimator. Let T be telescope. Let N be normal to plate when yielding ordi-nary signal, Let N^ be normal to plate when yieldingschiller signal. If COTr=2 cp then CON^TON^^y and, see Fig., a=(^—e and b=+ as the rays from C and to T must have been refracted, the true incident andreflected rays for the internal surface cannot have been these, but rather suchrays as C O and T O, making angles a and b with the surface normal O N, in .... sin a ... sin b , . , . , ^ ^ which sm a= and sm b= , // being the mean index of refraction for the moonstone. The normal to the internal surface will therefore be O N,and the angle between the two surfaces will be equal to NO N, denoted by d,. and, from the figure, b—d^a-f-d, or d= b—a For Ceylon moonstone cut parallel ^oi d=12° 5 and 65° 19, and isessentially independent of the angle of incidence. There is also a trans7nittedimage the color of which is complementary, that is, yellowish to reddish would indicate that the violet and blue rays were diffused and reflected,while the red, yellow, etc., penetrate. If the phenomenon were one of interfer-ence, then if for a certain angle of incidence the reflected color is blue, it mustpass into red for a larger incident angle, and this it does not do. The theory ofinternal reflection and absorption seems to best explain the phenomena. Similarresults were obtained with the Amelia Co., Va., albite and the adular ofZillerthal. a. j. m. Thin lamellae with bright metallic lustre. Color on cleavage, silver white withnormal incidence, reddish brown with oblique incidence. G. H. Streaklead gray. Ni2 TCg with traces P
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
