1888.] NATURAL SCIENCES OF PHILADELPHIA. 187 



During their flow or collection the sulphates often separate from 

 the chlorides ; borates, once precipitated, remain so, and give rise to 

 snffioni ; carbonic acid decomposes saline solutions more or less, but 

 chloride of sodium is scarcely ever entirely absent, and boron, iodine, 

 bromine and lithium are represented by traces. On account of this 

 remarkable action of carbonic acid on mother-liquor salts, the min- 

 erals accompanying troua thermonatrite etc., must be principally 

 sodium compounds, (chloride, sulphate, borate, silicate etc.) the car- 

 bonates of calcium and magnesium being separated out as fairly 

 insoluble precipitates. The carbonates of the alkalis decompose 

 silicates of lime in the rocks around forming carbonate of lime and 

 silicates of sodium and potassium as intermediate products, which 

 easily undergo decomposition, silica thereby being separated out in 

 the hydrated state : allowed to remain in contact with animal det- 

 ritus, saltpetre is produced ; magnesium chloride and sulphate con- 

 vert limestone into dolomite and certain silicates to serpentine ; the 

 sulphates of magnesium and lime also are often decomposed by cer- 

 tain organisms, giving rise to sulphuretted-hydrogen and a separation 

 of sulphur; lastly magnesium chloride dissolves all metallic com- 

 pounds, and even gold, hence mother-liquors with or without the 

 aid of water impregnated with carbonic acid, must have played a 

 great part in the deposition of most of our ores, by dissolving out the 

 metals contained in the different rocks around and concentrating 

 the same in cavities of various kinds. 



As the bituminous matter contained in brine-springs doubtless is 

 a 25roduct of decomj^osition of organic substances met by the mother- 

 liquors on their way, so the origin of petroleum, which is always 

 intimately connected with salt districts, can be accounted for by the 

 sudden destructive action of an overflow of mother-liquors over a 

 rich marine fauna and flora, the accompanying mud serving to shut 

 off access of air from the cadaverous remains, and the presence of 

 some chloride of aluminum enabling the formation of all the repre- 

 sentatives of the hydrocarbon series from the small particles of 

 anthracite occurring in lodes, to the masses of volatile hydrocarbons 

 of the vast oil districts. In short, in most littoral districts of past 

 and present oceans, from the depths of our mines to the summits of 

 the mountains, which ocean-water has not reached, but where mother- 

 liquor residues have been transported, do we find tangible proofs of 

 the remarkable effects of which mother-liquors have been the primary 

 cause. 



