ocks, of that variety of which
millstones are made, having quartz crystals disseminated through it, and
in general indurated by silicious matter in so fine a state of division
that the parts are nearly invisible. The latter substance seems to be
the result of a kind of sublimation which took place at the moment of
the formation of the trachyte.... Distinct craters are only seen at the
southern extremity of the chain. One of the finest observed by Dr Bone
was to the south of Tusnad. It was of great size and well characterised,
surrounded by pretty steep and lofty hills composed of trachyte. The
bottom of the hollow was full of water. The ground near has a very
strong sulphureous odour. A mile to the SSE. direction from this point
there are on the tableland two large and distinct _maars_ like those of
the Eifel--that is to say, old craters, which have been lakes, and are
now covered with a thick coat of marsh plants. The cattle dare not graze
upon them for fear of sinking in. Some miles farther in the same
direction is the well-known hill of Budoshegy (or hill of bad smell), a
trachytic mountain, near the summit of which is a distinct rent,
exhaling very hot sulphureous vapours.... The craters here described
have thrown out a vast quantity of pumice, which now forms a deposit of
greater or less thickness along the Aluta and the Marosch from Tusnad to
Toplitza. Impressions of plants and some silicious wood are likewise to
be found in it."[18]

Since Dr Daubeny's time there have been many observers over the same
ground, the most distinguished being the Hungarian geologist Szabo,
professor at the University of Buda-Pest. A countryman of our own has
also taken up the subject of the ancient volcanoes of Hungary, and has
recently published a paper on the subject. Professor Judd has confined
his remarks principally to the Schemnitz district in the north of
Hungary. But the following passage refers to the general character of
the formation. Professor Judd says:[19] "The most interesting fact with
regard to the constitution of these Hungarian lavas, which in the
central parts of their masses are often found to assume a very coarsely
crystalline and almost granitic character, while their outer portions
present a strikingly scoriaceous or slaggy appearance, remains to be
noticed. It is, that though the predominant felspar in them is always of
the basic type, yet they not unfrequently contain _free quartz_,
sometimes in very large pr