MINERALOGY; WITH A CLASSIFICATION OF SILICATES. 93 



III.— .1 CUisDification of SUicakn.—^ 36. The order of Silicates ; tliree suborders : Protosilicates, Protopersilicates, 

 Persilicates.— 37, 38. Relations of alumina in silicates ; distinctness of the first two suborders in igneous 

 masses and aqueous deposits.— 39, 40. Relation of the suborders to snbaërial decay. — 11. Relations of 

 dissolved silicates to magnesian and ferrous solutions. — 42, 43. Interrelations of the three suborders.— 

 44. Significance of atomic ratios. — 45-47. Chemical diflcrences and physical re.semblances ; foundations 

 of a truly natural system.— 48. The natural orders of Mohs and his school.— 49. Spathoid and colloid 

 types ; establishment of tribes.— 50. Hydroprotospathoids or pectolitoids, protospathoids, protadaman- 

 toids.— 51. Protophylloids, protocolloids or ophitoids.— 52. Hydroprotoperspathoids or zeolitoids, pro- 

 toperspathoids, protoperadauiautoids, protoperphylloiils, protopercolloids or pinitoids.— 53. Perada- 

 mantoids, perphylloids, percolloids or argilloids.— 54, 55. Chemical or genetic and mimetic relations ; 

 their relative significance.— 56. Tribes and species of the order Silicate.— 57. The Pectolitoid tribe, 

 with table.— 58, 59. Related magnesian silicates.— 60, 61. Formulas, unit-weight and unit-volume.— 

 G2. Table of atomic symbols and weights.— 63. The Protospathoid tribe, with table.— 64. Tribe of Pro- 

 tadamantoids, with table.— 65. Relations of wollastonite, amphibole and pyroxene.— 66. Tribe of Proto- 

 phylloids, with table.— 67-69. Tribe of Ophitoids, with table ; serpentines, their relation to the 

 spathoid and phylloid tribes.— 70. Tribe of Zeolitoids, with table.— 71. Prehnite and hamelite.— 72. 

 Tribe of Protoperspathoids.— 73. Tlie feldspathide family ; its genera and species.— 74. Table ; Hawes 

 on the feldspars of diabase; petalite.— 75, 76. The scapolite genus; Tschermak on its composition 

 and on intermediate species.— 77. The sodalite group.— 78. Cancrinite, a zeolitoid carbosilicate.— 

 79. Barylite, milarite, sarcolite and gehlenite ; eudialyte, wohlerite, ilvaite ; zirconlc and ferric 

 spathoids.— 80. Tribe of Protoperadamantoids, with table ; titanic, ferric and chromic species ; allan- 

 ites.— 81. Beryl, euclase, ardennite and axinite.— 82. Epidote and zoisite.— 83. The ferric species, 

 jpgirite, arfvedsonite and acmite.— 84. Spodumene, sapphirine, sfaurolite.— 85. The tourmalines ; five 

 distinct species ; their composition.— 86. Analyses of Rammelsberg; atomic volume of tourmalines, 

 with table.— 87. Tribe of Protoperphylloids, with table.— 88, 89. Connection of micas and chlorites ; 

 atomic ratios, hydration.— 90. Chloritic group; venerite, a cupric chlorite (footnote).— 91. Epichlo- 

 rite; an unnamed fibrous species; pilolite.— 92. Tribe of Pinitoids, with table; pinite and related 

 colloidal silicates; obsidian, pitchstone, tachylite, palagonite.— 93. Changes of iirotoperspathoids ; 

 epigenesis.— 94. Pseudoerystals from alteration ; foreign enclosures in crystals.— 95. Tribe of Perada- 

 mantoids, with table.— 96. The aluminic species ; the zirconic species ; variations in density.— 97, 98. 

 Tribe of Perphylloids, with table; history of pholerite and kaolin; talcosite and pyrophyllite.— 99. 

 Tribe of Argilloids, with table.— 100. Their frequent epigenic origin from feldspars and scapolites; 

 keramite; peculiar change of leucite.— 101. Argilloids from aqueous solution; indianaite.— 102. Two 

 great divisions of the spathoid type of silicates ; the adamantoids often hydrous; the phylloid type.— 

 103. Colloid type ; its significance ; mineral protoplasms. — 104. Devitrification by igneous and 

 aqueous processes ; the order of Oxydâtes ; its five tribes.— 105. Gerhardt on atomic volume of native 

 oxyds.— 106, 107. Volumes of various adamantoid oxyds compared.— 108. Tbe order of IMetallates ; its 

 suborders and tribes.— 109. Relations in these of hardness to volume.— 110. The order of Haloidates 

 with its suborders ; other orders ; the saline type ; salinoid tribes ; the order of Pyricaustates, or carbon- 

 aceous combustibles.— 111. Grouping and affiliation of orders ; four classes ; tabular view ; analysis 

 of Wiesbach's system (footnote).— 112. High molecular weights ; law of condensation ; geometric 

 forms.— 113. Relations between molecular weight and specific gravity of solids.— 114. Arbitrary weights 

 assumed.— 115. High molecular weights of some cobalt compounds.— 116-118. Silicotungstates and 

 phosphotungstates ; molybdates and vanadates ; complex inorganic acids of Wolcott Gibbs. — 119. 

 Their mineralogical significance.— 120. Relations to a new chemistry.— 121. The atomic unit in oxyds, 

 silicates, etc.— 122. Relation of this unit to specific gravity and to the undetermined unit of molecular 

 volume. — 123, 124. Minimum volumes of the cobalt-ammonia compounds and the salts of the complex 

 inorganic acids.— 125. Hypothetical formulas for some native silicates.— 126. Variations in densities of 

 solid species; their significance.- 127. Conclusions of Henry Wurtz; his hypothesis of molecular 

 volumes.— 128. Subordination of physics to chemistry.— 129. Conclusions as to a Natural System in 

 Mineralogy. — 130. Synoptical tables of the three suborders of Silicates. 



