ON THE CHANUK OF KBFKANUHUUTY OF UOHT, J199 to the refrangibility of the component parts of the dispersed light, (3) The colour of light in in general changed by internal dispersion, the new colour always corresponding to the new refrangibility. It in a matter of perfect indifference* whether the incident rays belong to the visible or invisible part of the spectrum. (4) The nature and intensity of the light dispensed by a solution* appear to be strictly independent of the state of polarization of the incident rays. Moreover, whether the incident rays be polarized or unpolamed, the dispersed light offers no traces of polarization. It seems to emanate equally in all directions, as if the fluid were self-luminous. (5) The phenomenon of n change of refrangibility proves to be extremely common, especially in the ease of organic substances such as those ordinarily met with, in which it is almost always manifested to a greater or I CHS degree. ((I) It atlbrds peculiar facilities for the study of the invisible rays of the spectrum more refrangible than the violet., and of tin* absorbing action of media with respect to them. (7) It furnishes a new chemical test, of a remarkably searching character, which seems likely to prove of great value in the sc.pa-rat ion of organic compounds. The test, is specially remarkable for this, that it leads to the independent recognition of one or more sensitive* substances in a mixture of various compounds, and shows to a great extent, before such substances have been isolated, in what, menstrua they are soluble, and with what age.nts they enter into combination. Unfortunately, these observations for the most part require sunlight. (8) The phenomena of internal dispersion oppose fresh difficulties to the supposition of a difference of nature in luminous, chemical, and phosphorogcnic rays, but are perfectly conformable * [The statement wan designedly limited to "a notation" (which I thought might include p;lanH, as a Kolution made at a hitfh temperature) hecaune it neemed (I priori very likely that there mi^lit bo a dependence) in tin* case of a crystal; and I think that 1 had already seen reason from ob.servatioM to at leant Biinpeet that such there was in the ease of crystals* of nitrate of uranium. Some time afterwards ahnoHt marked dependence wan observed in the cane of platinocyaniden. ]