350 PRINCIPLES OF STRATIGRAPHY 



(0.081 liter), and this, the mother Hquor, still contained the follow- 

 ing quantities of salts : 



NaCl 2 . 5885 grams per liter, or 12 . 9425 grams in 5 liters 



MgS04 1 . 8545 grams per liter, or 9 . 2725 grams in 5 liters 



MgCl2 3 . 1640 grams per liter, or 15 . 8200 grams in 5 liters 



NaBr 0.3300 gram per liter, or i .6500 grams in 5 liters 



KCl 0.5339 gram per liter, or 2.6695 grams in 5 liters 



8.4709 grams per liter, or 42.3545 grams in 5 liters 



Up to this point the separation of the salt had been fairly regu- 

 lar, but now the difference of temperature between night and day 

 became an influencing factor. At night nearly pure magnesium sul- 

 phate was deposited ; by day this was mixed with sodium and potas- 

 sium chloride. With the mother liquor at a specific gravity of 

 1.3082 to 1.2965, there was formed a very mixed deposit of mag- 

 nesium bromide and chloride, potassium chloride and magnesium 

 sulphate, with the double magnesium and potassium sulphate, cor- 

 responding to the kainite of Stassfurt, Germany. A double chlo- 

 ride of magnesium and potassium similar to the carnallite of Stass- 

 furt was also deposited. The mother liquor, which had again risen 

 to specific gravity of 1.3374, contained only pure magnesium 

 chloride. 



The Bar Theory of Ochsenius. In 1877 Carl Ochsenius (37), 

 following a previous suggestion of G. Bischof, sought to explain 

 the formation of extensive salt deposits of great thickness by as- 

 suming that they were formed in a nearly enclosed lagoon or bay 

 cut off from the main water body by a barrier beach or bar, across 

 which the w^ater was just able to pass. Concentration of the water 

 within the lagoon and over the bar proceeds by evaporation, and 

 as the water over the bar becomes denser and heavier it sinks and 

 flows down the bar and into the lagoon. If the surface evaporation 

 over the lagoon equals the inflow of salt-bearing waters, it is evi- 

 dent that precipitation of salt must result from the constant in- 

 crease in salinity, and the depth of the salt deposit will depend on 

 the original depth of the lagoon and on the length of time that these 

 conditions obtain. The constant addition of salts to the water of 

 the lagoon, brought about by the influx of sea water and its evapo- 

 ration from the surface of the lagoon, would result in the same con- 

 centration that is produced by evaporation of a given quantity of 

 sea water, as in Usiglio's experiments. The same result would be 

 obtained. In Usiglio's experiments, NaCl began to deposit when 

 one liter of the water was evaporated to 0.095, or about one-tenth 



