Bafalt. 45 1 latter is intelligible, bnt will not anfwer bis pur- pofe; for evcn this fort of fufion will render fub- tfances that undergo it porous, at lenft in fome deprec, as we fee in genuine compaei lava ; it will deprive zeolytes of the water of cryftalliza- tion, and dull the luftre of fliorls, for we fee the felfpars, and white garnecs of modern lavas, thus affcded. 2d, The effufion of melted lava into the fea would not barely fplit it into prifms, but fritter it to pieces ; this 1 have experienced by pouring melted bafalts into water, and throwing a crucible filled w.ith it into cold water. ( _ 3d, The circumllance of the vicinity of ba- faltic prifms in the fea adjoining the adual vol- canos of the Sicilian illand, cither proves nothing, as it does not follow that they are rather the effufions of thofe volcanos than the mother- ftones out of which lavas are formed; or, if we couple it with the above expcrifnent, it rather proves that they are not lavas. 4th, The difcovery of bafaltic pillars in an- tient, 'but now extind volcanos. is undoubtedly.. the corner ftone of all the volcanic theorics, par- ticularly where they feem accompanied with pouzzolana, volcanic afhes, pumice, tufas, Scc. Howevcr, it never once occurred to the natu- ralirts vvho made this difcovery, that the bala.ts might be the mother-flones of which lavas were formed, a fuppofition inlinitely_ more confiftent with all their properties and relations than that of their being themlelves lavas. Yet I am far froin thinking that all the moun- tains in which bafalts are found, feemingly ac companied as above mentioncd, are in realuv volcanic; few of thofe who have oblerved thetn G g 2 have