It will be seen from the following analyses that the sand, ashes, scoriæ, and compact lava have virtually the same composition--indeed they consist of the same substance in different states of aggregation. _Ashes._ _Sand._ _Scoriæ._ _Compact lava._ Silica 50·00 49·80 50·00 49·95 Alumina 19·08 18·20 19·00 18·75 Protoxide of iron 12·16 12·42 11·70 11·21 Protoxide of Manganese ·40 ·45 ·50 ·49 Lime 9·98 11·00 10·28 11·10 Magnesia 4·12 4·00 4·20 4·05 Potash ·60 ·49 ·69 ·70 Soda 3·72 3·60 3·40 3·71 Water ·36 ·29 ·33 ·23 Phosphoric acid } Titanic acid } traces traces traces traces Vanadic acid } Sesquioxide of iron } ------ ------ ------ ------ 100·42 100·25 100·10 100·19 With these we may compare the composition of the lava which issued from Monti Rossi in 1669, and was analysed by Lowe, and of an ancient lava of Etna ejected during an unknown eruption, and analysed by Hesser. _Ancient lava._ _Lava of 1669._ Silica 49·63 48·83 Alumina 22·47 16·15 Protoxide of Iron 10·80 16·32 Protoxide of Manganese ·63 ·54 Lime 9·05 9·31 Magnesia 2·68 4·58 Soda 3·07 3·45 Potash ·98 ·77 ----- ----- 99·31 99·95 The sublimations from the fumaroles are chiefly chloride of ammonium, perchloride of iron, and sulphur. An analysis of the gases of the fumaroles of 1865 gave the following results:-- Carbonic acid 50·5 Hydrosulphuric acid 11·9 Oxygen 7·1 Nitrogen 30·5 ----- 100·0 An account of microscopic analysis of some of the lavas of Etna, for which I am indebted to Mr. Frank Rutley, will be found appended to this chapter. He considers that they are Plagioclase-basalts, and occasionally Olivine-basalts; and that they consist of Plagioclase, Augite, Olivine, Magnetite, Titaniferous iron, and a residuum of glass.