COMPOSITION OF SOME PUMICE AND LAVA FROM THE PACIFIC, 237 
Lava.—From Port Resolution, Island of Tanna. This 
black vesicular rock, with a pitchy or resinous lustre on the fr het 
fractured surfaces. The weathered surfaces are brown, and in the 
interior of some of the vesicles scattered through the lava are 
white glassy crystals of sae 
= a eet ; 
Sita moisture avs eee! 
ve as bin 53°312 
Alotin po ies oes Bie coe OE 
Tron pct is ie sis .-. 17°339 
Iron monoxide... ann sc 20S 
Magnesia ... “T27 
Lime ie or ey As om s. 9°058 
Manganese monoxide ... ot gue w. «17443 
§ , oa Be ns ish 3°417 
Potash .~ seh wie a ik «- 3°347 
. gr. 2°686 at 15°C. 99°791 
The proportion of iron to this rock is unusually large 
Lava.—From the island of Tanna. This is a black scoriaceous 
and vesicular lava; the freshly fractured surfaces are highly 
lustrous, like the former lava it contains isolated small glassy 
crystals of felspar. 
Chemical composition : 
Moisture ... wet iis se bie bets EEL 
Silica aia avs sie er me +. 56°755 
Alumina a na den «-. 21°096 
Tron sesquioxide . ms ne bu a. O21 
Tron mo nc ; eS BA ac «+ 3021 
angane eat a0e i ea ... traces 
a tecaidias ren ve ie es its : sy 
Lime inh 9-014 
Potash... ots wit a ibe eh OZ 
2°66 at 15°C. 100-724 
Thus ii is a He hehe difference in the composition of 
th wo lav; 
ne Comparative Table. 
White pumice, Bondi. Black pumice, Bondi, 
becom at 100°C... 1818 “147 
Sili ... 68°149 63°630 
Akai mina ae -. ~16°493 17994 
Iron sesquioxide iki ati: 5°838 
Iron monoxide a ae traces 
M ese monoxide... “256 “691 
- 4005 4°205 
esia .. ‘ . none none 
Soda... oii ‘ae ee SSSE 4°252 
Potash ei nate poe. LOUD 3°809 
99.447 100-566 
