50 ROCKS FROM NEW BRITAIN AND NEW IRELAND. 
Chemical composition. 
Loss at 100° C. 
Combined water, by direct weighing 5-975 
Silica 56°566 
\lumina 17 °820 
Isom meaquioxide.......... vi weiideds 2°910 
Tron monoxide 645 
Manganese Monoxide ........00nse+seeeee “841 
Lime 5106 
Magnesia traces 
Potash 2-610 
soda 3094 
99°592 
Specific gravity, 2°359 at 212° C. 
Lava, from the volcano, New Britain. With a dark grey bas 
scoriac 
mineral partly soluble with effervescence in hydrochloric acid. 
Chemical composition, 
ss at 100° C. 119 
Loss at red heat 390 
Silica 57°465 
Alumina 19-200 
Tron sesquioxide 3°833 
Tron monoxide 3°223 
Manganese monoxide,.........csessseeer "974 
Lime — 
Magnesia A es 
oe 9-470 
Potash aa Ateoe 
Carbon dioxide ees trace 
Sulphur trioxide ‘ 
99°097 
black colour contains a few scattered felspar ¢ stals, and an" 
is in addition characterized by the dba of vesicular ae 
Sulphur, from the crater of the volcano in Blanche Bay, el: 
form of small pieces, evidently broken off an incrustation, of loe : 
kness, very a 
i i 
Bet aA, 
small crystals, but for the most part it is somewhat i, 
resembles flowers of sulphur. 
