204 BEPOKT OF NATIONAL MUSEUM, 1899. 



as regards the common salt it contained, that it was impossible to carry on the 

 manufacture from this source without loss. In 1839 the Prussian Government who 

 were the owners of these saline springs, commenced boring with the object of dis- 

 covering the whereabouts of the bed of rock salt from which the brine had been 

 obtained and in the year 1843, seven years after the commencement of the borings, 

 the top of the rock salt was reached at a depth of 256 metres. The boring was con- 

 tinued through another 325 metres into the rock salt without reaching the bottom of 

 the layer. At this total depth of 581 metres the boring was suspended. On ana- 

 lysing the brine obtained from the bore-hole, it was found to consist, in 100 parts by 



weight, of- Sulphateofcalcimn 4.01 



Chloride of potassium 2. 24 



Chloride of magnesium - 19. 43 



Chloride of sodium 5. 61 



A result not only unexpected but disappointing, since the presence of chloride of 

 magnesium in such quantities dispelled for the time all hopes of striking on the pure 

 rock salt. The Government, however, guided by the opinions expressed by Dr. 

 Karsten and Professor Marchand, namely, that the presence of chloride of magnesium in 

 such quantities was probably due to a deposit lying above the rock salt, determined 

 to further investigate the matter, and in the year 1852 the first shaft was commenced, 

 which after five years had penetrated, at a depth of 330 metres, into a bed of rock 

 salt, passing on its way, at a depth of 256 metres, a bed of potash and magnesia salts 

 of a thickness of 25 metres. 



On referring to the section of the mines [Plate 4], it will be seen that the lowest 

 deposit of all consists of rock salt. The bore-hole was driven 381 metres into it 

 without reaching the bottom of the layer. Its depth is therefore unknown. The 

 black lines drawn across the rock salt deposit represent thin layers of sulphate of cal- 

 cium 7 millimetres thick, and almost equidistant. The lines at the top of the rock 

 salt represent thin layers of the trisulphate of potash, magnesia, and lime as the 

 mineral Polyhallite [Specimen No. 67754, U.S.N.M.]. The deposit lying immediately 

 on the bed of rock salt consists chiefly of sulphate of magnesia as the mineral Kie- 

 serite [Specimen No. 62417, U.S.N.M.]. Still farther toward the surface the deposit 

 consists of the double chloride of potassium and magnesium, known as the mineral 

 Carnallite, [Specimens Nos. 40225, 62416, U.S.N.M.] mixed with sulphate of magnesia 

 and rock salt. The deposit to the right, on the rise of the strata, consists of the 

 double sulphate of potash and magnesia combined with one equivalent of chloride 

 of magnesium, and intermingled with common salt to the extent of 40 per cent. 

 This double sulphate is known as the mineral Kainite [Specimen No. 64735, U. S. N. M. ] 

 and is a secondary formation, resulting from the action of a limited quantity of water 

 on a mixture of sulphate of magnesia and the double chloride of potassium and 

 magnesium, as contained in the uppermost deposit previously spoken of. 



The upper bed of the rock salt, resting on a thick bank of Anhydrite [Specimen 

 No. 64740, U.S.N.M.], is also a later formation. Almost imperceptible layers of Poly- 

 hallite are present in this deposit and at greater intervals than in the lower and 

 older deposit. It has therefore probably originated from the action of water on the 

 older deposit. This upper bed of rock salt varies in thickness from 40 to 90 metres, 

 and its extent is comparatively limited. It is worked in preference to the older 

 deposit, where both exist in the same mine, it being of much purer quality, aver- 

 aging about 98 per cent in the mines of the New Stassfurt Mining Company and in 

 the Royal Prussian mines. 



Sixteen different minerals have as yet been discovered in the Stassfurt deposits. 

 They may be divided into primary and secondary formations. Those of primary 

 formation are rock salt, Anhydrite [Specimen No. 64740, U.S.N.M.], Polyhallite 

 (K 2 S0 4 , MgS0 4) 2CaS0 4 , 2H 2 0) [Specimen No. 67754, U.S.N.M.], Kieserite (MgSO 4 , 



