438 Forbes — Chemistry of the Primeval Earth. 



author, who considers that the chlorine would chiefly, if not entirely, 

 be in combination with the metals of the alkalies and alkaline earths, 

 as chloride of sodiam, etc. 



According to Dr. Hunt, the hydrochloric acid in this atmosphere 

 was derived from the mutual reactions of sea-salt, silica, and water. 



This, in the first place, is supposing the pre-existence of compound 

 bodies, in a case where he had previously informed us that there 

 were only dissociated elements engaged in the formation of this 

 igneous sphere. For the sake of argument, however, let it be 

 admitted that sea-salt, water, and quartz were present, then it is still 

 contended that the reaction, described by Dr. Hunt, could not have 

 taken place. All chemists know that quartz, water, and sea-salt, if 

 heated together in a confined space, or if the vapor of water and salt 

 be passed over highly heated quartz, that such a reaction would take 

 place forming hydrochloric acid gas along with silicate of soda. 

 This, however, could never occur in nature in the case under con- 

 sideration, for long before the quartz had attained a heat sufficient 

 to enable it to act upon the salt, all the water would have evaporated 

 into space ; and if the heat were continued, the vapour of the salt 

 would follow, leaving the quartz behind. 



As the greater part of the sodium is considered to have been at 

 once combined with the chlorine, it follows, of course, that the 

 silicate of soda could not have played so important a part in the 

 formation of the primary crust as is ascribed to it by Dr. Hunt ; and 

 there would also be no necessity for the extraordinary theory that 

 the saltness of the sea is due to the rain of hydrochloric acid 

 " flooding the half-cooled crust" with a highly heated acid deluge, 

 which extracted the soda from its silicate, leaving the quartz 

 behind;^ and it is therefore conjectured that neither geologist nor 

 chemist will be contented with this explanation of the salt in the 

 sea. 



Having thus opposed the views of Dr. Hunt, as set forth in his 

 lecture, the author of this communication will in a few words sketch 

 out the chemical reactions which he supposes to have been charac- 

 teristic of this period of the earth's history. 



The act of combination of the elements is regarded by him as 

 having given rise to a molten sphere, surrounded by a gasiform 

 atmosphere, both of which were composed of concentric layers or 

 zones of different densities and chemical composition. 



This sphere, it is imagined, would arrange itself into three grand 

 zones, (each zone, probably, containing sub-zones), somewhat as 

 follows : — An external zone, or crust of highly acid silicates, the 

 bases being chiefly alumina and potash, with minor quantities of 

 soda, lime, magnesia, oxide of iron, etc. ; below this a second zone of 



' The silica produced from such decomposition of silicates is of the specific 

 gravity of 2-2, is soluble in alkaline solutions, and does not polarize light, which is 

 not the case with the silica contained in any of the older rocks, which Dr. Hunt 

 supposes to have been so formed. The chemical and physical properties of the 

 silica of such rocks indicate them to have been derived from, the breaking down of 

 acid rocks analogous to granite. 



