Dr. Carl Ochsenius — On Metalliferous JDeposifs. 311 



and their formation, it is clear that the mother liquor salts or their 

 solutions must be looked upon as very important geological agents 

 or elements. Mother liquor salts are one of the results of the 

 sequence of consecutive changes which occur in a bay or an estuary 

 separated from the ocean by a horizontal bar. When an influx of 

 fresh water takes place in such an estuary, it is only a question of 

 the height or configuration of the bar whether such a bay contains 

 fresh, brackish, or salt water, the sediments in the interior of the 

 estuary being of course of the same nature as the water which, it 

 contains. Now the changes in the size of the bar, whether from 

 ocean storms, from land floods, or from other disturbing causes, pro- 

 duce the series of different layers which are found so characteristic- 

 ally marked in the Tertiary basin of Paris (which at the Tertiary 

 epoch received the Loire) and in other localities, 



" The precipitations which take place in such a bay, without fresh 

 water influx, and which receives within the bar only so much sea- 

 water as is necessary to compensate for the loss of water in the bay by 

 evaporation, form a rock-salt bed which, in the absence of disturbing 

 causes, is constituted of gypsum, rock-salt, and anhydrite, together 

 with salt-clay, which represents the inorganic detritus from the shore. 

 Mother liquor mainly composed of magnesium salts remains in a state 

 of solution, and as soon as the level of this solution reaches the lower 

 level of the bar, it flows out of the bay over it, in consequence of its 

 specific gravity, which is much greater than that of the incoming 

 sea-water. The marine animals having power of motion have long 

 before this left the bay, as the concentration of its contents in its 

 earlier stage makes their stay there impossible, the remainder are 

 afterwards destroyed, leaving only traces of their existence in the 

 first layers of gypsum. The contemporary presence of a comparatively 

 well-developed fauna and flora in or near salt water basins or 

 bitter lakes, with concentrated contents, is never observed." 



These views were brought forward at Jena in 1876, and have since 

 been embodied at greater length in a treatise on the formation of 

 rock-salt beds and their mother liquor salts.^ The (if the expression 

 be allowed) mathematical result of the process described, that is, the 

 complete filling up of the salt-forming bay with gypsum, rock-salt, 

 and anhydrite with salt-clay, must have occurred only in the rarest 

 instances. The alternations, etc., observed in rock-salt layers are 

 not now referred to, excepting to say that they are to be easily 

 explained as resulting mainly from differences in the height of the 

 bar. It seems quite certain, that in the majority of cases the surface 

 of the anhydrite, instead of being level, contained many depressions 

 which retained mother liquor in considerable quantities, and this 

 mother liquor forms the subject of the following observations. 

 Mother liquor, in contradistinction to sea- water, contains no sulphate 

 of calcium ; less chloride of sodium than ocean water, but more 

 chloride of magnesium, potassium and lithium ; and besides these 

 all the bromides and iodides. The borates, notwithstanding that 



1 Carl Ochsenius, "Die Bildung der Steinsalzlager und ihrer Mutterlaugensalze," 

 Halle, 1877, and Nova Acta, 1878. 



