CHARACTER OF THE SOLUTIONS. 59 



definition, solutions may be made by mingling gases and gases, gases and 

 liquids, gases and solids, liquids and liquids, liquids and solids, and solids 

 and solids. The solutions resulting from these various combinations may 

 be gases, liquids, or solids, or partly two or all. Gaseous solutions may be 

 formed by the mingling of gases and gases, of gases and liquids, and 

 of gases and solids." Liquid solutions may be formed by the mino-ling of 

 gases and gases, of gases and liquids, of liquids and liquids, of solids and 

 liquids, and of gases, liquids, and solids. Solid solutions may be formed 

 by the mingling of gases and solids, of liquids and solids, of solids and 

 solids, and of gases, liquids, and solids. But however complex the origin 

 and however numerous the components, the compounds with which the 

 geologist has to deal are gases, liquids, and solids. The two common 

 combinations which he has to consider are gaseous solutions and solids 

 and liquid solutions and solids. The liquid solutions are universally 

 aqueous. The solids are the rocks. The combinations gaseous solutions 

 and solids, and aqueous solutions and solids will be treated under Parts I and 

 IT of this chapter. 



PART I. GASEOUS SOLUTIONS. 



Since the geological work of gases and vapors can not be practically 

 discriminated, the term gas is here used to cover both gases and vapors. 



The gases which are important in rock alteration are oxygen (0 2 ), 

 sulphur (S 8 to S 2 ), water gas (H 2 0), ammonia (NH 3 ), carbon dioxide (C0 2 ), 

 sulphurous oxide (S0 2 ), boric acid (H 3 B0 3 ), hydrochloric acid (HC1), and 

 hydrofluoric acid (HF). 



Never is one of these chemical compounds at work alone upon the 

 rocks; at the place of action there are always solutions of several gases. 

 Mineralizers in rocks, according to the original definition, are substances 

 which act in the gaseous condition; 6 but it will be seen (pp. 490-494) 

 that the term has been practically restricted to peculiar gases under special 

 circumstances. Notwithstanding the definition of the term, the action of 

 water solutions containing certain compounds, which if alone would be 

 gaseous, has been spoken of as due to mineralizers. The term miner- 

 alizers, if it is to serve any useful purpose, should be definitely restricted 



ffl Daniell, Alfred, A text-book of the principles of physics. 3d ed., Macrnillan Co., New York, 

 1895, p. 330. 



6 Expression " Agents mineralisateurs " first used by Elie de Beaumont and defined by H. Ste;- 

 Claire Deville: Comptes rendus des Seances de l'Academie des Sciences, vol. 52, 1861, pp. 920, 1264. 



