BENSCH — EXPERIMENT ON BASALT. 19 



The author had previously proved (Meeting of the Imp. Geol. 

 Institute, Dec. 18, 185.5) the presence of three varieties of granite, 

 coequal in age, and not separated by any contact-fissure, in the 

 Carlsbad territory. He had further found evidence that all the 

 thermal springs in question belong to one of these granites ; and that 

 "Von Hoif's line" is merely a local phenomenon. Dr. Hochstetter 

 now proves that the Carlsbad springs occur along two parallel lines, 

 — the one the Sprudel, the other the Muhlbrunn, — both running 

 N.W. & S.E., and each having a secondary fissure, parallel to the 

 principal line. The superficial valleys correspond to the direction and 

 extent of these two fissures, which are essentially connected with the 

 clefts produced by gradual decomposition in the '* Carlsbad granite." 

 The principal set of fissures have a N.W. & S.E. direction, and the 

 secondary set from N.E. to S.W., corresponding to the run of 

 numerous quartziferous and siliceous veins. As to the situation of 

 the thermal springs, their central point is the Sprudel, corresponding 

 to the point of intersection of the principal Sprudel fissure with the 

 secondary fissure of the Tepl Valley. The Marktbrunn and the 

 Schlossbrunn are beyond the Tepl, along the continuation of the first 

 of these fissures. The next springs occur along lateral and secondary 

 fissures, and have their supply of water more or less directly from 

 the principal Sprudel fissure. As these communications partly take 

 place through the Schlossberg, which is interposed between the prin- 

 cipal Sprudel fissure and the secondary fissure of the Muhlbrunn, 

 the origin of the warm waters everywhere pouring out of this hill 

 may be easily explained, together with the other phenomena obser- 

 vable in the Carlsbad springs in general. An accurate knowledge of 

 the fissures giving rise to the springs, and a correct map illustrative 

 of these features, would be of great practical importance, both for 

 regulating the springs, and for preventing any operations that might 

 injure them either in quality or quantity. [Count M.] 



Experiment on Basalt. By A. Bensch. 



[Leonhard u. Bronn's N. Jahrb. f. Min. n. s. w. 1855, p. 597 ; and Ann. Chem. 



Pharm. 91. p. 234.] 



Some years since the author reduced to a very fine powder, in water, 

 by means of a porphyry slab and grindstone, some of the basalt of 

 the Hirschberg near Grosse-AImerode, intending to apply it to the 

 glazing of bricks. The wet powder remained many months in a glass 

 cup covered with paper, and became so hard a mass that a very 

 severe blow of a hammer could scarcely separate a fragment from 

 the mass. The fracture of this mass was similar to that of the 

 natural basalt. The mass presented a black nucleus, of waxy lustre, 

 surrounded by a somewhat less dense substance, but still very hard 

 and grey. Exposed for some time to the air, the surface of the 

 altered basalt exhibited an efflorescence of carbonate of potash, and 

 of this r8 per cent, could be removed by water. 



