365 
1909-10.] The Chemistry of Submarine Glauconite. 
a sweetish odour. After another such treatment with acid, again followed 
by caustic soda, the glauconite is observed to disintegrate superficially. 
The alkaline liquor is now poured off and the residue shaken up with 
repeated doses of boiling distilled water, when the glauconite is rapidly 
and completely broken up and forms a bright-green suspension which does 
not readily settle. The process is repeated until only non-glauconite 
minerals remain behind, and the combined suspensions (which are slightly 
alkaline) are rendered faintly acid, when the glauconite is at once coagulated 
as a green flocculent precipitate. This is washed by decantation with hot 
water, filtered off, dried at 110°, and powdered. 
The property thus possessed by glauconite of going into colloidal 
suspension affords a means of separating greensands into their constituents 
more quantitatively than was possible heretofore. Two specimens of 
submarine greensand placed at disposal by Sir John Murray were dealt 
with on these lines. 
1. A highly glauconitic greensand dredged by U.S.S. Albatross (1904) 
in the Pacific, off Panama, lat. 6° 53' N., long. 81° 42' W., depth 556 fathoms.* 
It contains 5 per cent, of calcium carbonate and 9 per cent, of fine wash- 
ings, which are green in colour and consist almost entirely of disintegrated 
glauconite. The glauconite grains are all of 0*25 to 0'6 mm. diameter, and 
approximate in shape to prolate ellipsoids : no obvious casts were observed. 
The grains have striae of a light yellow non-calcareous incrustation wandering 
irregularly over the surface, whereby incipient decomposition is indicated ; 
they are thus not such fine specimens as the Tuscarora grains, which 
are undoubtedly the purest glauconite hitherto brought up. From 12 gr. of 
washed and decalcified greensand, 036 gr. of mineral residue was obtained : 
the mineral species are mainly felspar (predominating) and quartz, with a 
few flakes of hornblende. The quantitative composition of the greensand 
may be summed up as follows : — 
Calcium carbonate 
Glauconite grains 
Minerals 
Fine glauconite . 
5 per cent. 
83 
3 
100 
2. A very inhomogeneous, not predominantly glauconitic greensand 
dredged on the Agulhas Bank, lat. 34° 38' S., long. 8° 33' E. ; in 110 fathoms 
* Murray and Lee, Mem. Mus. Comp. Zool ., xxxviii. p. 40, 1909. These authorities 
express the opinion (p. 41) that the sample may have been subjected to washing during or 
after the dredging. 
