146 Analyses of Books. [Aufi. 



from volcanoes. His proofs are as follows : — I. From the nature of 

 basalt. Specimens of basalt occur consisting at one end of perfect 

 basalt, at the other of clay, and these two substances pass insensibly 

 into each other. Such a mineral could not possibly have been 

 ejected from a volcano. Greenstone and basalt are found inter- 

 mixed, and gradually passing into each other, at the Meisner 

 mountain, and in other places. Now as greenstone cannot have 

 been acted on by fire, it follows that basalt likewise could not have 

 been formed by any such agent. Basalt, from what place soever it 

 comes, is always possessed of the same characters, and yields the 

 same constituents. But this is not the case with lava, which varies 

 considerably, according to the nature of the rock, by the melting 

 of which it has been formed. Hence basalt must be an aqueous 

 production, as these alone exhibit that uniformity of composition 

 and properties for which basalt is so remarkable. Basalt contains 

 about 20 per cent, of iron. Now there is no rock that could furnish 

 it with such a proportion. Hence it cannot have been formed by 

 the fusion of any other rock. II. From the heterogeneous substances 

 contained in basalt. These substances are, 1. Crystals or grains of 

 basaltic hornblende, olivine, augite, mica, and felspar. These are 

 regularly distributed as in porphyries, which could not be the case 

 if the basalt had been in a state of fusion. They retain their crys- 

 talline characters, and do not exhibit the slightest traces of the 

 action of fire ; though some of them, as felspar, are more fusible 

 than the basalt itself. They exactly fill the cavity in which they are 

 deposited, whereas in lava the crystals are smaller than the cavities 

 in which they are, and therefore often rattle when the lava is 

 shaken. All these circumstances are inconsistent with the notion 

 that basalt has been in a state of fusion, or that it is lava. 2. Ca- 

 vities usually of a round shape, some empty, and some occupied 

 wholly or in part with balls or geodes ol green earth, steatite, cal- 

 careous spar, zeolite, chalcedony, quartz, and other substances. 

 They differ from the grains already mentioned in being evidently of 

 posterior formation to the basalt in which they are found. Now no 

 such substances ever occur in true lava, which never has an amyg- 

 daloidul structure. 3. Fragments of older rocks. Fragments of 

 sandstone and of limestone quite unaltered occur in basalt. Petri- 

 factions also have been seen in it, though rarely. Such appearances 

 are quite inconsistent with the notion of its being lava. 4. Basalt 

 contains about five per cent, of water of composition, while no 

 water whatever is found in lava. III. From the form of basaltic 

 rocks. Basalt forms regular beds, frequently very thin, and ex- 

 tending for a very considerable way. It is inconsistent with the 

 nature of lava to take any such form. Therefore basalt could never 

 have been in a state of fusion. IV. From the position of basalt 

 with regard to other rocks. It sometimes lies immediately 

 over or under coal, as is the case in the Meisner mountain ; 

 yet the coal is not the least altered in its nature, though some 

 alteration must undoubtedly have been produced if the basalt, 



