342 HISTORY OF GEOLOGY AND PALEONTOLOGY. 



phyre, phonolite, and related rocks generally recognised, 

 but also Huttonian views respecting the plutonic origin of 

 the granite-grained massive rocks became more widely 

 accepted. 



Nevertheless, new objections were raised against the 

 pyrogenetic origin of the granite-grained rocks. Keilhau 

 asserted in his work on the "transitional formations" of 

 Norway that the granite in that area had originated from the 

 conversion of clay slates. The Munich chemist, Johann 

 Fuchs, in 1837 attacked the doctrine of pyrogenetic origin in 

 a series of papers entitled Ueber die Theorien der Erde. He 

 pointed out that fusion experiments had never succeeded in 

 reproducing granitic rock artificially, even although individual 

 elements of the rock had been obtained; further, minerals 

 having different melting-points were present in granite, yet 

 these minerals had not consolidated from the magma in the 

 order that corresponded with that of their fusibility, therefore 

 he argued it was absolutely erroneous to suppose that granitic 

 rock had formed merely as the result of slow cooling and 

 consolidation. Fuchs advanced the view that granite, and the 

 granitoid rocks generally, had consolidated from an amorphous 

 magma saturated with water. 



In 1845, Schafhautl succeeded in reproducing quartz 

 artificially by the application of superheated water in a Papin 

 crucible, and this result seemed to confirm Fuchs' views. On j 

 the other hand, Fournet, in 1844 an< 3 1847, pointed out that 

 there were certain conditions under which the fusing-points of 

 substances were lowered to temperatures much below the 

 points at which they usually solidified. In papers written 

 about the same time, Durocher, referring for support to 

 Fournet's Theory of surfusion, supposes a mass of granite to 

 be originally a homogeneous magma, which can remain fluid 

 until the fusion temperature of felspar is almost reached. 

 At about 1500 C. the separation of felspar, quartz, and 

 mica begins, and the different minerals solidify according to 

 their tendency to crystallisation. Durocher thinks the later 

 formation of quartz crystals might in this way be explained, 

 since felspar passes more readily than quartz from the viscous 

 to the solid state. 



Scheerer, the illustrious chemist and geologist, offered 

 formidable objections to the purely pyrogenetic origin of 

 granite in a memoir published in the Bulletin of the French 



