ON THE CRYSTALS IN LAVAS.' O/j^^ 



lirae-kilri, which he quotes as an example in favour of his supposed to be 

 system. " This pvodaction," says he, « resembles inter- homblend^w 

 iially certain hornblendes of the Alps, and compact and lata in a kiln, 

 homogeneous lavas. Its external part is puffed out like that 

 of lavas, its surface is covered with a yellow glaze, and its 

 cavities are lined with little crystals." In a note he adds: 

 *• let not the reader suppose, that the stones of this kind 

 had fallen accidentally into the kiln, as this was impossi- 

 ble." 



I shall offer no direct objection to the fact ; as this would But pieces of 



require sL knovvledge of the production itself, and particu- other stone get 

 ^ ° * . ' r jj^^o limekilns 



larly of the vicinity of the hme-kiln : but I shall offer a accidentally. 

 general remark, that may throv*^ some light on its origin^ 

 It is a very common circumstance, for fragments of other 

 stones, which the workmen have overlooked, to get among 

 the broken limestone, with which the kiln is filled, and not 

 to be observed till the lime is taken out. In this- case, in- 

 stead 6f sL piece of lime we find a stone covered on its sur- 

 face with a vitreous glaze, which being broken aippears to 

 be granite, serpentine, or some other vitrifiable stone. In- 

 stances of this are frequent in the lime-kilns in my neigh- 

 bourhood. Tc( be certain, that such fragments could not 

 be introduced, there must be nothing but calcareous rocks 

 in the country, these must even be free from quartzose or 

 siliceous nodules, and there must be no other kind of stone 

 either belonging to the soil or adventitious. Thus it is very 

 probable, and from a great number of instances I am per- 

 suaded it was the fact, that the product of the lime-kiln 

 abovementioued was originally a stone of a different kind 

 from that commonly burned in the kiln. 



« Naturalists," continues Mr. Fl. de Bellevue, « who That laras are 

 still believe, that rocks on which volcanic fires have acted incompletely 

 r -11 • r . r ■ J,,- fluid said to be 



have experienced only an impertect tusion, and that their a supposition. 



crystals have remained intact amid their fluid paste, are 

 obliged to have recourse to a multitude of suppositions, 

 to explain the state in which the lavas are found when 

 cold." 



These naturalists have recourse to no supposition : they But it is a fact, 

 find it not necessary. Nothing in the lava changes its form 

 or nature when it cools. The foreign substances it contains 

 R 2 in 



