HISTORICAL SKETCH. 



11 



granite powder together with a mixture of two parts of sirupy phosphoric 



acid and one part of water to only 100, he received more than 10 times as 



much gas as was evolved at 300 without the acid, or about 1.5 volumes. 



Table 7 comprises Gautier's analyses of the gases expelled at red heat. 



TABLE 7. 



The role played by these gases in vulcanism, and their connection with 

 thermal waters, is discussed in more recent papers. 1 Following Gautier, 

 Htittner 2 showed by a series of experiments that when a stream of dry car- 

 bon dioxide is passed over a rock powder at a temperature of 800, carbon 

 monoxide results, owing to a reduction of the dioxide, as this investigator 

 believes, by some of the hydrogen given off from the rock. As the miner- 

 als orthite and gadolinite yielded no carbon monoxide, though abundant 

 hydrogen, when gelatinized in hydrochloric acid, he came to the conclusion 

 that this gas does not exist in rocks. 



In 1905 there appeared a paper by Albert Brun, 3 "Quelques Recherches 

 sur le Volcanisme," based upon studies of lavas from Vesuvius, Stromboli, 

 and other Mediterranean volcanoes. While no complete gas analyses were 

 undertaken, much experimentation was done, covering the expulsion of 

 gases and vapors at or near the fusion point of the lavas. This author ex- 

 presses the opinion that it is the liquefaction of the rock which produces 

 the gases, these being engendered by chemical bodies contained within the 

 lava itself. The gases recognized are nitrogen and its derivative ammonia, 

 chlorine with derived hydrochloric acid, and hydrocarbons. The nitrogen 

 is assigned to nitrides, and the ammonia to reactions between nitrides and 

 hydrocarbons, while a dissociation of chlorides furnishes free chlorine which 

 may take hydrogen from hydrocarbons to form hydrochloric acid. A 

 source for hydrogen and carbon dioxide is recognized in hydrocarbon com- 

 pounds, though Brun was less interested in the gases expelled below the 

 melting-point of the lava. 



1 Gautier, Comptes Rendus, vol. 132, pp. 740-746 and 932-938 ; Economic Geology, 

 vol. 1 (1906), pp. 688-697. 



2 K. Huttner, Zeitschrift fur Anorg. Chem., 43 (1905), pp. 8-13. 

 3 A. Brun, Archives des Sciences phys. et naturelles, Geneve, 1905. 



