vill INDEX TO CHEMISTRY, MINERALOGY, AND GEOLOGY. 
Technical terms relating to stratification, explana- 
tion of, 123. 
Tellurids, definition of, 59. 
Temperature, low degrees of, obtained by means 
of carbonic acid, 11. 
Terebratule, the, abundant in most fossiliferous 
strata, 150. 
Tertiary middle series, position and thickness of, 
183; difficulty of arranging and classifying 
tertiary deposits, 184 ; organic remains found 
in the, ib.; Hausmann and Bronn’s arrange- 
ment of the tertiary masses, ib. ; the Paris ter- 
tiary rests on the cretaceous, 186; order of 
the strata in the London tertiary, ib.; the 
upper tertiary or molasse, 187; fossils of the 
tertiary period, 190. 
Theodolite, use of the, in measuring the heights 
of mountains, 115. 
Thomsonite, 75. 
Tile-stone, the, occurrence of, in the Devonian 
system, 147. 
Tin ore, 69. 
Tineal, 81. 
Top series, the, 194. 
Topaz, 73. 
Tourmaline, 76. 
Tours, the artesian well at, 198. 
Trachyte, 96. 
Trachytic conglomerate, breccia, and tufa, 109; 
rocks, 206 ; lava, 212. 
Transition rocks, 143; slate formation, ib. ; 
great extent of the transition-slate rocks, 145 ; 
three systems of the transition-slate distinguish- 
ed in England, ib. ; extensive distribution of 
the, 147 ; examples of, 148 ; enumeration of 
the principal fossils in the, 149. 
Trap rocks, 98 ; trap conglomerate, 108. 
Traventine, 194. 
Treuil, curious phenomena in a coal bed near, 
Loi: 
Triclinie system, characters of the, 51. 
Trilobites, features of the fossil, 152. 
Trimetric system, the, 49; fundamental and 
derivative forms of, 50. 
Tripoli, 103. 
Tula, caleareous, 103; newer calcareous, 194 ; 
silicious, ib. 
Turbinites, characters of the, 151. 
Upper tertiary, principal rock species of the, 
186 ; divisible into two groups—the marl form- 
ation and the sub-Apennine formation, 187. 
Valleys, peculiarities of, 117 ; striking interest of 
the study of the relations of, in a mountain 
system, 118; primary or longitudinal, lateral | 
or cross, and secondary, ib. ; stratification of, 
122 ; valley of Pyrmont, 123; of excavation 
or denudation, 124. 
Variegated sandstone group, the, 161; fossils, 
composition, mountain forms, and distribution 
of, 162. 
Variolite, 99. 
668 
Vegetable remains, great abundance of, in the 
coal strata, 155. 
Veins, nature of, 129; shape, course, relative 
ages, and filling up of, 130; connexion between, 
and the inclosing rocks, 131 ; intersections of, 
ib. ; interlaced, 132; true character of mine- 
ral, ib. ; principal theories of, 133 ; the princi- 
pal, in the Silurian and Devonian systems, 
146; various contents of, in granite rocks, 
202 ; of the pyroxene rocks, 205. 
Vitriols, nature and different kinds of, 79 ; uses 
of the, 85. 
Volcanic rocks, 208 ; voleanie ejectamenta, very 
different characters of, 213 ; origin of volcanic 
mud, ib.; volcanic sublimates, 214; striking 
homogeneity of the form of a volcanic moun- 
tain, ib.; distinction between volcanic centres 
and voleanie lines, 217. 
Voleanoes, definition of, 208 ; active and extinct, 
ib.; pseudo-voleanoes, 209; distribution of, 
ib. ; usual shape of, and height of the princi- 
pal, 210; dimensions of the craters of, ib. ; 
lava streams from, 211 ; general nature of vol- 
canic ejectamenta, 213; gaseous exhalations 
and deposits from voleanic waters, 214; form- 
ation of several, in recent times, ib.; erup- 
tion of, generally announced by earthquakes, 
216; aerial, nature of the phenomena so eall- 
ed, 217; various hypotheses with regard to, ib. 
‘Voleanoid rocks, 206. 
Vosges sandstone, the, 161. 
Walter’s safety tube, 13. 
Washing-bottle, the, 35. 
| Water, formation of, 21, 23; method of remov- 
ing, from animal or vegetable organisms, 27 ; 
infiltration of, through the solid roofs of 
caverns, 129 ; influence of, upon rocks, 199. 
Water-bath, description of the, 26. 
Waterfalls, striking results produced by, 200. 
Wavellite, 80. 
Waves, formation of caves by the force of, 199. 
Wealden group, constituents of the, 168. 
Weiss’s nomenclature of the different systems of 
crystallization, 47 et seq. 
Wenlock strata, the, 146. 
Werner, the views of, respecting the formation of 
veins, 133. 
Wernerite, 75. 
White chalk group, characters of the, 177 ; 
upper formation of the, in various localities, 
178. 
Whitestone, 96. 
Wolff apparatus, the, 38. 
Wolfram, 80. 
Wollaston’s reflecting goniometer, 53. 
Wiirtemberg, section of the rock salt formation 
at, 165. 
Yellow sand, 112. 
Zwickau, subterranean combustion at, 209. 
