Of Dißinilive Charaßtrs. 4^7 in the melted lava. This conclufion is grounded on the following reafons: ift Becaufe thefe fhorls or bafaltines are found in rocks confeffedly not of volcanic origin, for inftance in granite *• *d Becaufe the thin fufion requifite for cryf- taihzation would convert them into glafs, a ftate to which they do not even approach 5 d Becaufe the heat requifite for their fufion is fuperior to that which flowing lava generally poffclfcs, and yet the fufibility oFboth is. exaftly {he farne; if, therefore, they were really fufed, fo alfo rauft the lava have been, which yet is not true, aswe have already feen._ .... c 4th Becaule the percolation or Infiltration ot the particks of which they confift through fo vifcid a lubftance as flowing lava is not eafily conceived, that is, is not conformable either to obfervation, experiment, or analogy. cth Becaufe their cryftallization in the midft of a denfe vifcid fubftance is equally wcon- ceivable. ,, Thefe reafons are ftill more ftrongly applicable to white garnets (Vefuvian) felfpars, and olivins which are Hill lefs fufible than bafaltines. Mr. Faujas and Baron Diedrich imagined that fhorls expofed to volcanic fires might be dif- tinguiflled from thofe found in fubftances that had riever feit their aftion, by their influence on the magnetic needle. But Mr. Sauflure o erve the fhorls found in the neighbourhood of Geneva, to exert the iame influence as thofe contained ra fubftances confefledly volcanic. * Helvet. Magaz. p. 156. * Saufl, p. 67. § II.