" 2.697
Lapilli ejected in 1444 2.420
Compact lava ejected in prehistoric times 2.854

A very decided change in the specific gravity was found to take place
after fusion. This can only be accounted for on the supposition that a
chemical change is effected during the fusion:--

_Sp. Gr._ _Sp. Gr._
_before fusion._ _after fusion._

Pyroxene of Etna 3.453 2.148
Felspar " " 2.925 1.361
Olivine " " 3.410 2.290
Lava of 1865 2.771 1.972
Ancient basaltic lava from } 2.854 2.000
the Scogli de'Ciclopi }
Ancient basaltic lava from } 2.795 1.947
Aci Reale }

It will be seen from the following analyses that the sand, ashes,
scoriae, and compact lava have virtually the same composition--indeed
they consist of the same substance in different states of aggregation.

_Ashes._ _Sand._ _Scoriae._ _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