235. To the facts and reasonings given above, I shall, in this note, add a few remarks, tending to show, that whinstone is not of volcanic, nor of aqueous, but certainly of igneous origin. It is asserted, (§ 62,) that carbonate of lime and zeolite are often contained in whinstone, but never in lava, and that this circumstance may sometimes serve to distinguish these stones from one another. With respect to carbonate of lime, in particular, it seems evident, that this substance cannot enter into the original composition of any lava, because the same heat which melted the lava, would, where there was no greater pressure than the weight of the atmosphere, expel the carbonic acid and produce quicklime. Notwithstanding this, rocks containing carbonate of lime, have often been considered as lavas, into the pores and cavities of which, calcareous matter having been carried by the infiltration of water, had crystallized into spar. Thus SPALLANZANI, in his account of the Euganean Hills, in Lombardy, describes some of the rocks as abounding at their surface, and even in their interior, with air-bubbles of various sizes, from such as are hardly perceptible, to some that are half an inch in diameter; and which, he says, are all of an oval figure, with their longest diameters in the same direction. This he considers as a proof that the rock is a genuine lava; for the air-bubbles prove the stone to have had its fluidity from fire; and by their elongation in the same direction they prove, that the mass when fluid was also in motion. Spallanzani adds, that _many of these cavities are filled with crystals of the carbonate of lime, an effect of the infiltration of water_.[120] [Footnote 120: Voyages dans les deux Siciles, tom. iii. p. 157. Edit. de Faujas de St Fond.]