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OCR
MINERALOGICAL REMARKS. 287 they differ in their external appearance, are the fame, even in the difpofition to lofe their property of intumefcing on heating, by this being performed in a covered veflel *. For it is’clear, though the learned chemift did not advert to it, that it is exa@tly the fame caufe, which made the clear and tranfparent fragments of the previoufly heated pebbles not lofe their qualities on being again placed in the furnace, which made their matrix remain unafledted by fire when heated in a clofe veflel, and then be not affected by the blow-pipe : and I lately faid that the grey matrix was intermixed with red, and I have {mall fpecimens in which the red predominates; this need therefore only have had untunicated nuclei (for the red pebbles, it will be recollected, were quite opake) to be perfectly fimilar, and it really has; but they are generally tunicated till they become by exfoliation of the fize of a poppy feed, and it is then difficult to examine them. The refemblance of the two, that from near Kamfchatka and that from Tokay, is ftrikingly alike. The fofil on which I have been fo diffufe, is not a rare foffil in this part of Hungary. The matrix forms, according to Mr, Fichtel, * On this point Mr. Pallas and Mr. Lowitz feem to differ: for the former fays, that the fragments of the internal part of one of thefe pebbles which-had been heated, gave the fame appearance, on being again heated, as the pebble itfelf did at firft; whilft Mr. Lowitz not only fays that the internal part continues clear when in the pebble, but its fragments on fubfequent heating lofe nothing of their tranfparency. e. inet = o 35
