Natural Deposits of Potash in Germamj. 413 



are followed by red marls and variegated or mottled marls and clays, 

 to the depth of about 100 feet. Then comes an extensive bed, or 

 rather a series of beds, of anhydrite and gypsum. On descending 

 further we came to a number of beds of saliferous marl or clay, strongly 

 impregnated with salt ; and iimncdiately below these beds of marl we 

 met with layers or beds, about 200 feet in extent, containing a variety 

 of salts, some of which are remarkably beautiful in appearance, shining 

 and glistening in some parts, dull in others, but always distinguished 

 by a peculiarly bitter taste. 



These are the potash deposits ; from them at present a very large 

 quantity of potash is manufactm-ed, both for agricultural purposes and 

 for the guni^owder manufactories ; for maniifacturers of gunpowder 

 now use German potash-salts, decomposing them with Chilian nitrate 

 of soda, and thus obtaining by a double decomposition chloride 

 of sodium, or common salt, and nitrate of potash, which is in every 

 respect equal to the Indian nitre. The variegated or mottled salts 

 containing potash are called, in Germany, skim-salts, because they 

 have to be skimmed off, or removed from above the extensive salt 

 deposit of almost pui-e rock-salt. 



Below these 200 feet of potash deposits, or crude potash-salts, occur 

 a number of beds of impm-e rock-salt, the impurities being chiefly 

 gypsum and anhydrite in veins, in some places passing through the 

 rock-salt, and in others interspersed with it, giving it a somewhat dirty 

 colour. Then we find a deep and as yet unfathomed layer of almost 

 pure rock-salt. The first experiment in boring was made in 1839, 

 and the trial continued till 1851, when a depth of 1851 feet was reached 

 without getting to the bottom of the rock-salt, which was discovered at 

 the depth of 760 feet below the surface. Thus the pure rock-salt is at 

 least 1000 feet in thickness. 



A specimen which I picked up will give you some idea of the purity 

 of the salt. You will observe that it is perfectly transparent ; it does 

 not attract moistm'e, even on a very damp day, and this is due to its 

 great pm-ity. The analysis made by Professor Eammelsberg of Berlin 

 gives 97|- per cent, of chemically -pure chloride of sodium, and no 

 chloride of magnesium, which causes ordinary salt, including some 

 varieties of table-salt, to become damp on exposure to the air. 



Since 1855 the mines of Stassfurth have been in full operation, and 

 liave furnished annually above 50,000 tons of pure salt, besides a large 

 quantity of impure salt, which is used for agricultui-al purposes, and in 

 giving cattle a relish with their food. 



These mines of potash-dejposit have a peculiar interest for agricul- 

 ture, but they have likewise been a perfect mine of discovery to the 

 scientific chemist, presenting well-defined chemical compounds pre- 

 viously unknown to the mineralogist. I refer here more especially to 

 one salt — a natural salt here found in very large masses — which has 

 been called carnallite, after Mr. Von Carnall, the director of some 

 Prussian mines. It is from this combination, which is distinguished 

 by a different form of crystallization from ordinary rock-salt, that 

 potash is chiefly obtained. It occurs sometimes in beautiful white 

 crystals, which look almost like sugar-candy. This carnallite is a 



