562 
PROFESSOR STOKES ON THE CHANGE OF REFRANGIBILITY OF LIGHT. 
INDEX TO THE PRECEDING PAPER. 
N.B. The figiu’es refer to the articles, the letters to the notes. 
Absorbing and reflecting power, determination of, with 
respect to invisible rays, 194-196, 201-204. 
Absorption, on the cause of, 237, 238 ; connexion of, with 
internal dispersion, 59, 60, 63, 71, 76, 120, 126, 146, 
148. 
Air expelled from water, 172. 
Appearance of highly sensitive media, 27, 29, 164. 
Archil, 65-71. 
Canary glass, 73-77j F. 
Chemical appUcations of internal dispersion, 67-70, 205- 
214. 
Clearness of sensitive fluids accounted for, 86. 
Coloured glasses, fundamental experiment with, 7 ; nature 
of the blue reflexion in orange glasses, 79 ; examined 
for dispersion, 167, 168. 
Colomdess glasses, internal dispersion in, 78 ; defect of 
transparency of, 22, 202, 217-219, A. 
Colours of natural bodies, 174-178. 
Concentration and dilution, effect of, 185-188. 
Crystals, natural, 165, 166. (See Fluor-spar, Uranium.) 
Datura stramonium, solution, 43; paper, 95; capsules, 
117. 
Dispersion, true and false, defined, 25 ; distinguished, 26, 
29; cautions, 169-173; usual features of true, 44-46 ; 
on the cause of true, 226-236; nature of false, 179; 
instances, 181 ; apphcations, 180, 182. 
Epipolic dispersion, 1 ; explanation of, 6. 
Esculine, 31, 212. 
Explanation of terms, 21-30, 101. 
Eye, opacity of the, 220, K. 
Fixed hnes of the invisible rays, exhibited, 16; description 
of the, 21-23, A, H; effect of viewing through a prism 
the fixed lines shown by means of sensitive media, 17, 
89-93, 100. 
Flames, effect of various, 197-200. 
Fluor-spar, 32-36. 
Groundsel, petals of the purple, 120. 
Guaiacum, solution, 37-41 ; washed paper, 98; solution 
of, used as a test object, 200. 
Heat, effect of, on the sensibihty of glass, &c., 184. 
Horse-chestnut, 31, 212. 
Illuminating power of the highly refrangible rays, 104, 
105, B. 
Internal dispersion, 2. 
Lavender rays, 105, B. 
Leaf-green, absorption, 47-52 ; internal dispersion, 53-61 , 
97, 118, 121. 
Lightning, effect of, J. 
Linear spectrum, 107-109; results obtained with a, 113- 
136, &c. 
List of highly sensitive substances, 239. 
Litmus, 72. 
Mercurialis perennis, 62-64. 
Methods of observation, general, 13, 17, 110, 112. 
Mutual aetion of incident rays, negative results with re- 
ference to the, 215, 216, 235, 236. 
Permanganate of potassa, absorption, D. 
Phosphorescence compared with internal dispersion, 220- 
225. 
Phosphorogenic rays of an electric spark, nature of the, 
219-221, A. 
Polarization, absence of, in dispersed hght, 1, 15; of the 
incident rays a matter of indifference, 20. 
Polarized light, direetion of the vibrations in, 183. 
Quartz, transpareney of, 202, 217-219; train, 204, H. 
Quinine, absorption of the \dolet by a solution of sulphate 
of, 11; internal dispersion in a solution of, 14-20 ; 
strong afiinity of, for hydrochloric, hydrobromic and 
hydriodic acids, 205-211. 
Rays, course of, exhibited, 193. 
Reflecting power (see absorbing power). 
Refrangibility of dispersed light, lower than that of the 
incident, 80, 102, 230-236; nature of the, 81, 82; 
illustrated by a surface, 84, 85. 
Results, principal, 240. 
Screen, on the choice of a, 189-192, F, G. 
Sea-weeds, red, 121-126. 
Strata of equal dispersion in crystals, 167. 
Test objects, 110, 114, 200. 
Triangle, e.xperiment with a paper, 58. 
Turmeric, tincture of, 42; paper, 87-91. 
Uranium, salts of the peroxide, &c., 157-162, 213, C, I 
(see also canary glass); delicate test of, 159 ; absorption 
of light by salts of protoxide of, 160, 163. 
Washed papers, 87-98. 
