44^ S/cond Appendix, nothing efcapes but water and air, and/ the al- terauonthey thereby receive muft for ever re- main. Balaxts m particular are as fufible as they cai L,, ‘ u PP 0 ftd to have ever been. T he fecond reafon tbat appears tn me a de- monftrationthat bafalts nor traps are r.ever fub- jetted to the operations of heat is, that they contain fubftances in a ftate abiolutely incompa- nble vvith iuch operations; for inftance, they contain mild calcareous earth, as an eflential in- gredient in their compofition, which muft necef- farily have been calcined, at Itaft in the fuperfi- cial parts of thofe bafalts, in a heat much infe rior to that which could fufe the bafalts. They often contained zeolytes, which muft at ieaft have loit: their apprcpnated water; they contain horb.ende cryftals, which yet are fufible, and confequently deftruftible in as iow a heat as ba- falt itlclf; they often contain calcareous fpars. whicn muft have been dccompofed in the iame heat, nay more, neither calcareous fpar nor zeo lytes are everfound in any modern (tbat is to fay, in any uhdoubted) lava, as Mr. Dolomicu acknowledges. Ponces, 424. Neither Mr. Hamilton nor Mr. Volght take any notice of this objedion. Mr. Dolomieu endea- vours to evade it, by allowing the liquidity of lava not to proceed from fire. With refped to ihorls, he exprefles himfelf thus : “ It is no “ longer nccelfary to refute the opinion of thofe “ wno have believed that the fhorls of lavas “ were produds of fire, and that they vvere form- “ cd either during their fufion or their cooling; it is too evident that their exiftcnce preceded ue fufion ct lava *and again, “ It will be * Ponces, 246. “ fl