I 62 2 



of many fpecies of ftones when heated. Many forts of ftones 



are fbft v.hile in their ftrata, as fandRones, limeflones, &c. 



but lofe their water and acquire hardnefs bv e-poflire to the 



air. But perhaps the mofl efFedlual ineans of convincing our 



author that a confolldating power i?iay take place in water, 



is to remind him tliat in many cafes it does cfliiallyXal^t place. 



Thus mortar inade by pouzzolona or terras is 'Jvell known 



to harden under water ; nay Mr. Smeaton has obfervcd it to 



throw out under water a ftalacftite, which alfo hardens in that 



Atuatlon. Fdify J^ofic, § i8i. The calcareous depofits formed 



in certain waters, and which attain a ftony hardnefs', are a 



further proof that immerfion in water does not always obftrudl 



the formation of folid maffes. " But (adds our author) we 



" find firata confolidated by various fubftances which water 



'* cannot diflblve ; thus we have water confolidated by calcareous 



" fpar, a thing perfe(5tly diidnguifliable from the flaladlitlcal 



•' concretion of calcareous earth, in confequence of aqueous 



" folution ; we have ftrata made folid by the formation of 



" fluor, a fubftance not foluble, as far as we know, by water ; 



" we have ftrata confolidated by filiceous earth in a fl;ate wholly 



" different from that in which it was obferved, on certain 



" occafions, to have been depofited by water; we have ft:rata 



" confolidated by fulphureous and bituminous fubftances which 



" refufe a watery folution ; laftly, we have fome confolidated 



" by almoft all the various metallic fubftances. If it is by 



" means of water that all thefe interftices. have been filled 



" with thofe materials, water muft be, like fire, an imiverfal 



" folvent, 



