1888.] NATURAL SCIENCES OF PHILADELPHIA. 183 



ratory experiments. This is especially the case with borates, mague- 

 sium borate in particular, as well as with silica and titanic acid. As 

 the depositing process continues, the greater part of the deliquescent 

 salts remains dissolved in the upper layers and constitutes the mother- 

 liquors (ifzt/ierZaw^'eji), which contain, along Avith sodium chloride, 

 the potassium and magnesium compounds etc. We have then in the 

 mother-liquors above the rock-salt, approximately arranged in order 

 of solubility : sulphateof magnesium, chloride of potassium, chloride 

 of magnesium, borates, bromides, lithium salts, an iodine compound 

 probably magnesium iodide, and calcium chloride. In the course 

 of the continued growth of the rock-salt beds and likewise of the 

 mother-liquors, the latter attain the level of the bar and commence 

 flowing out seawards directly over it, as soon as their specific gravity 

 can overcome the current of the inflowing sea-water. After this 

 stage is reached, ordinary sea-water can only have access through 

 the upper portion of the bar-mouth, the lower part being occupied 

 by the outgoing mother-liquors. 



At this point the last.stage of the process begins viz., the deposition 

 of the uppermost bed of sulphate of calcium in the form of the 

 Anhydrithut Portions of the concentrated mother-liquors get mixed 

 with surface-water washed in, and this, from the increased amount 

 of the hygroscopic chlorides of magnesium and calcium, lessens the 

 superficial evaporation of the bay, and hence the influx of sea water 

 diminishes gradually. The sulphate of lime in the sea-water that 

 has flown in, is now precipitated, the other salts mixing with the 

 mother-liquors and flowing out with them over the bar. As the 

 gypsum falls through the concentrated mother-liquors, its water of 

 combination gets abstracted, and a seam of anhydrite is by degrees 

 deposited. Sometimes a compound is formed of gypsum with the 

 sulphates of magnesium and potassium (the latter by double decom- 

 position of sulphate of magnesium and chloride of potassium) viz., 

 polyhalite, a mineral occurring in the upper strata of many salt 

 deposits. The bay meanwhile assumes the character of a bitter-lake 

 and influences the surrounding shores, the organisms inhabiting the 

 littoral waters dying oflT, and the neighboring rock disintegrating to 

 dust, which is blown into the lake, forming the material for the 

 salt-clay ; this offers a good explanation for the increased thickness 

 of salt-clay seams often observed in the upper layers of salt deposits. 



A regular succession of these briefly described phenomena will 

 rarely be found in nature. Every alteration in height of the bar, 



