MINERALS USED AS FERTILIZERS. 69 



time, almost the entire demand for alkalies for industrial uses 

 bore upon the same product, until the invention, toward the end 

 of the last century, or LcBlaiic's process for the manufacture 

 of soda from common salt ; for until that time, soda in the 

 various forms in which it was imported from the Orient or 

 prepared from seaweed ashes, was a comparatively costly pro- 

 duct. LeBlanc's invention was most timely in that it very 

 quickly diminished materially the production of potashes 

 which, in view of the increased demand for alkalies for in- 

 dustrial uses, seriously threatened the depletion of agricultural 

 lands, and of woodlands as well, of one of its most essential 

 ingredients. Yet as there are many industrial uses in which 

 soda cannot replace potash, the manufacture of potashes con- 

 tinued to a greater or less extent, as no other available source 

 except the ashes of land plants, was then known. The pro- 

 duction of potassic chlorid from the mother-waters of sea salt 

 in the spontaneous evaporation of sea water for the manu- 

 facture of common salt, was on too small a scale to influence 

 materially the manufacture of potashes. 



Discoi'cr\ of Stassfurt Salts. The depletion of potash had 

 become so serious a matter in the agricultural lands of Europe, 

 that for a time much research was bestowed, and prizes offered 

 for an economical method of producing potash salts from feld- 

 spar, on a commercial scale. But the problem had not been 

 satisfactory solved when, in the year 1860, attention was called 

 to the fact that the saline deposits overlying certain large 

 rock-salt beds that had been developed by borings near Stass- 

 furt in Prussia, contained so large a proportion of potash salts, 

 as to render their purification and conversion into fairly pure 

 sulphate and chlorid technically feasible. The impulse having 

 been given, the potash industry dcveloj>ed rapidly in that 

 region as well as in the adjacent portions of Saxony, where the 

 same formation underlies; the production of "Stassfurt 

 Salts " rapidly assumed a greater development than that of the 

 rock-salt which had originally prompted the enterprise, and 

 numerous additional boreholes demonstrated an unexpectedly 

 wide extension of the same beds. At the present time, in con- 

 sequence of such development, the manufacture of potashes 

 from plant ash has almost ceased, outside of Canada and 

 Hungary; and the production of potash salts in the Stassfurt 



