CHEMICAL SCIENCE. 301 



so-called igneous rocks, views published originally in 1837, but not here- 

 tofore generally accessible to the American public. Fuchs opposed the 

 Plutonist and the theory of upheavals, without, however, accepting literally 

 doctrines of the Xeptunists. He reasoned against the view that the crys- 

 talline rocks were once in a state of fusion, as follows : using granite as 

 the illustration. If granite were once in a molten condition, then as it 

 cooled, in the first place, quartz must have crystallized out, and would 

 have sunk down through the still molten mass, while felspar and mica 

 must have crystallized at a much later stage of the cooling, as the necessary 

 result of their different degrees of fusibility. Further, the inclusion of ar- 

 senical pyrites, sulphide of antimony, tourmaline, garnet fluor-spar, &c. 

 by quartz, is incompatible with the crystallization of the latter from a state 

 of fusion. Accordingly the doctrine of upheavals cannot be sustained. In 

 enunciating his own views, Fuchs begins with the proposition, that amor- 

 phism must precede crystallization, and assumes that originally, the solid 

 part of the earth consisted of silica and silicates in the amorphous form, 

 while the liquid portions were largely, made up of solutions of lime and 

 magnesia or their carbonates, in the then existing excess of carbonic acid. 

 " This I conceive to have been the primal, or chaotic condition of our 

 globe ; this may indeed haA T e been preceded by another condition, but to 

 this state it must have come before the formation of rocks could begin." 



The formation of rocks, according to Fuchs, began with the silicates. 

 The stupendous crystallization thus induced must have developed light and 

 heat. The latter must have acquired great intensity, even that of ig- 

 nition. The products were different as determined by circumstances, 

 namely: granite, syenite, porphyry, mica slate, c., which in fact, as is 

 known, pass into each other, and may be included together under the 

 term granitic rocks. Also at a later period members of the silicious group 

 were formed, but not so perfectly as at first ; examples are clay-slate, and 

 manv sand-stones. The lime-stones and calciferous rocks began to be 



V 



formed simultaneously with the silicious rocks, and the production of both 

 ran parallel through all epochs, down to the most recent times. After the 

 deposition of carbonate of lime, the vast quantities of carbonic acid which 

 had served to hold it in solution, became the material which should espe- 

 cially contribute to the sustenance of organic nature. Says Fuchs, " this acid 

 had from the beginning of the creation a three-fold office ; firstly to keep 

 the carbonate of lime separated from the silicates, and for a certain time 

 to retain it in solution ; secondly to furnish the atmosphere with oxygen, 

 and thirdly to supply carbon for the production of fossil coal and organic 

 bodies. In recent geological times have probably been formed by their 

 decomposition, two kinds of products, namely : bituminous, containing 

 much hydrogen, and humus-like, containing both hydrogen and oxy- 

 gen." 



Fuchs notices here the objection, that there is not now enough free oxy- 

 gen in the atmosphere to form carbonic acid with all the carbon of the 

 globe. Accordingly a part of the oxygen originally present must have 

 been devoted to other purposes, and he assumes that it was mostly con- 



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