1909-10.] Composition and Character of Oceanic Ked Clay. 187 
| 
Depth 
(fathoms). ! 
Locality. 
Minerals. 
South 
Pacific. 
8. 
Challenger Station 288. 
2600 
40° 3' S. ; 132°. 58' 
W., about midway 
between Chili and 
New Zealand. 
Phillipsite, felspar, 
volcanic glass. 
9. 
Albatross Station 4701 : 
contains 11 per cent, 
of CaCO ?/ 
2265 
19° IT S. ; 102° 24' 
W., about 1900 
miles due W. of 
Pisagua. 
36° 41' S. ; 158° 29' 
E., about midway 
between New 
South Wales and 
New Zealand. 
Decomposed basic 
mineral (greenish 
flakes), plagioclase, 
augite, phillipsite. 
10. 
Challenger Station 
165 A : contains 19 
per cent, of CaC0 3 . 
2600 
Quartz, felspar, horn- 
blende, mica, vol- 
canic glass, magne- 
tite. 
11. 
Challenger Station 171 A. 
2900 
Indiai 
25° 5' S. ; 172° 56' 
W., about 1000 
miles N.N.E. of 
New Zealand. 
it Ocean. 
Plagioclase, magne- 
tite, hornblende, 
quartz, pumice, red 
glassy particles, 
basaltic fragments. 
12. 
Valdivia Station 176. 
2933 
24° 0' S. ; 95° 8' E., 
about 1100 miles 
due W. of Cape 
Cuvier (W est 
Australia). 
Pumice, volcanic 
glass, felspar ; very 
angular. 
13. 
Gauss Station 96. 
2700 
26° 0' S. ; 54° 0' E. ; 
about 400 miles 
S.E. from Mada- 
gascar. 
Experimental . — All samples were prepared for analysis by being 
deprived of calcium carbonate and, as far as possible, of coarse minerals 
and sea-salts. Calcium carbonate was removed, if present, by means of 
dilute acetic acid, coarse minerals by simple elutriation, and sea-salts by 
repeated decantation with distilled water. The last trace of sea-salt 
cannot be extracted in this way, because the wash-water ultimately becomes 
so poor in electrolytes that the clay refuses to settle within practicable time ; 
however, the purified material, when boiled out with dilute nitric acid, 
gives only a faint opalescence with silver nitrate and no reaction whatever 
with barium chloride, so that it was deemed unnecessary to take residual 
sea-salt into account in the analytical statements. 
The separation into anhydrous and hydrous silicates (the “ insoluble ” and 
“ soluble ” of the older analyses) was effected by the method originally due 
to Forchhammer,* which is now universal in ceramic analysis : f the hydrous 
* Pogg. Ann., xxxv. p. 331, 1835. 
t For a lull account see Berdel, Sprechsaal , 1902, pp. 881, 919, 959. 
