of the Island of St. Paul. 359 
b. From the upper surface of the volcano. 
5. Bog iron-ore from the upper margin of the crater. Y.— 
The sample consists of some fragments, an inch or more in dia- 
meter, of a deposit resembling bog iron-ore, coarsely granular, 
full of holes, and of a reddish-brown colour. The weathered 
surface is whitish; the fresh fractures exhibit many cavities, 
several lines in diameter, filled with a red, ochrey, friable earth. 
Here and there glassy streaks of greater solidity occur in the 
mass. Acid is absorbed without effervescence ; calcination pro- 
duces no change in the red colour. After the surface had been 
well blown, the bright-red friable inner parts were crushed in 
distilled water, and, after the clear water had been poured away, 
boiled with muriatic acid. The fluid became greenish, and a 
whitish silica, free from iron, remained behind. Ten analyses of 
this mass furnished 16 striking organic forms :—6 Polygastria, 
6 Phytolitharia, 3 Polycystina, 1 Geolithe. Decided marine 
forms were mixed with very striking freshwater forms, otherwise 
than in the other cases. 
6. Bright-red earth from the highest points of the island, under 
the turf. No. 164,—The entire upper margin of the crater pre- 
sents red earth of this kind, apparently the upper beds of lava 
and cinders decomposed into iron-ochre or brown ironstone. 
The sample is a bright, rusty-red, fine earth, which does not 
effervesce with acid, and, when calcined, becomes first blackish, 
and afterwards only a very little darker, at last even resuming 
-its original colour. In washing, the greater part is suspended 
in the water, and only a few sand-grains remain; these, also, 
form rough particles between the fingers, whilst the mass is of 
impalpable fineness. When the red earth is boiled with muriatic 
acid, iron is extracted, and a white earth, scarcely diminished in 
volume, is left. 
This earth is exceedingly remarkable when examined by the 
microscope. It consists, with the exception of a very few quartzose 
glassy sand-grains, entirely of well-preserved fine, and coarser 
silicious particles from grasses, with a few shells of Polygastria 
intermixed. That these particles, covered individually with a thin 
coat of peroxide of iron, which ceases to be perceptible under a 
magnifying power of 300 diameters, were produced, as might be 
supposed from appearances, by the weathering and decomposition 
of beds of lava and cinders, is impossible, from the sharpness and 
good preservation of their forms; but a baking and hardening of 
the decomposed grassy vegetation to form superficial cindery 
rocks, and an action of the volcano upon such masses, colouring 
them with peroxide of iron, is readily conceivable even at a high 
temperature; the circumstance that the oxide of iron in them is 
26% 
