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THE POPULAR SCIENCE MONTHLY 



conditions of temperature and pressure, ob- 

 tained the sulphurets, oxides, and metallic 

 salts he sought, with the bed-rock that held 

 them. 11. Uaubrec has reproduced cassi- 

 terite, and several of the minerals that are 

 found with it, by subjecting water and the 

 right oxides to the action of chloric and 

 fluoric vapors. MM. Fouque and Michel 

 Levy, also following the indications of geo- 

 logical observation, have obtained the min- 

 erals of volcanic rocks in crystals, not only 

 as isolated minerals, but also with the asso- 

 ciations under which they form real rocks, 

 resembling the natural rocks so closely as 

 to deceive. Other processes have been em- 

 ployed, varying in their nature and opera- 

 tion according to the minerals which it was 

 desired to produce, or the substances from 

 which their production was sought. The 

 number of minerals obtained by the differ- 

 ent processes is so great that the mere enu- 

 meration of them all would be tedious. The 

 most obvious and simple process is that of 

 fusion. Some substances, among them the 

 silicates, tend, when they cool from a liquid 

 condition, to form amorphous glasses. Many 

 of these, it has been found, will crystallize 

 when heated again nearly up to the melting- 

 point. By this process of sub-fusion several 

 of the feldspars, oxide of iron, spinel, gar- 

 net, and other minerals have been obtained. 

 When the substance does not melt readily, 

 or is liable to decompose before melting, 

 the process is aided by heating it with some 

 suitable solvent. Thus have been obtained 

 apatite, wolfram, tungstate of lead, pyrites, 

 boracite, and other minerals. A consider- 

 able number of minerals may be crystallized 

 from solutions in water of different tem- 

 peratures. A curious feature of this pro- 

 cess is that it operates sometimes to render 

 a hydrate anhydrous. At other times the 

 water may serve as a base to remove a por- 

 tion of acid. It has been noticed also in 

 this process that the crystals may be made 

 larger by exposing them to repeated varia- 

 tions of temperature. Some minerals have 

 been obtained from volatile solvents by 

 vaporizing the solvents, when the minerals 

 would be precipitated. Another process is 

 by the action of two substances upon each 

 other with or without the addition of elec- 

 trical excitement, as when the oxide of cop- 

 per is produced by the action of the solu- 



tion of sulphate of copper and galena ; 

 another is by the reaction of vapors and 

 gases on other bodies of similar nature or 

 on solids a process in which chlorine and 

 the members of its group may play an im- 

 portant part. 



M. Faye's Theory of the Solar System. 



M. Faye, having pointed out in a former 

 paper certain particulars in which the nebu- 

 lar hypothesis of Laplace fails to account 

 for the movements of the planets, has pub- 

 lished a second paper propounding a theory 

 by which the retrograde movements of a 

 part of the planets may be reconciled with 

 the direct motions of the other planets, as 

 results of the same laws. The theory of 

 Laplace presupposes the existence of an 

 immense degree of heat expanding the mass 

 of the sun and its atmosphere to the ex- 

 treme limits of the solar system, and a con- 

 traction by cooling, in the course of which 

 planetary rings were thrown off by an ex- 

 cess of centrifugal force. M. Faye objects 

 to the hypothesis of great heat as one of 

 which there is no evidence ; moreover, if 

 the heat had existed and contraction had 

 taken place by cooling, the outer atmos- 

 phere of the sun would have participated in 

 the cooling and contraction so fully that it 

 would have adhered to the mass, and no 

 rings would have been thrown off. The 

 new theory which he proposes in the stead 

 of that of Laplace is based on the observa- 

 tion of the nebulae, bodies which astronomers 

 have often regarded as the points of de- 

 parture for evolutions very different from 

 those pictured by Laplace for evolutions 

 tending to formations of the most varied 

 character, as simple, double, triple, and 

 quadruple suns, and globular aggregations 

 of minute suns numbered by thousands. 

 Would it not be natural, he asks, to accept 

 the suggestion of these facts, the more so 

 since our system belongs to the most com- 

 mon type that of a nebula at first vague, 

 then undergoing a central condensation, ab- 

 sorbing itself gradually and regularly into a 

 nebulous star and finally into a solitary sun? 

 t'nder this view, heat would no longer have 

 to be invoked arbitrarily as an external 

 agent ; we would, on the other hand, see it 

 gradually developed in certain points of the 

 nebula, as the proper result of the energy 



