a 
MOLLUSKITE. 433 
This substance is of a dark brown or black colour, and 
occurs either in shapeless masses, which are irregularly 
distributed among the shells and other organic remains, in 
sandstone, limestone, &c., or as casts of shells, or occupying 
their cavities, as in the specimen Lign. 139, fig. 3, which is 
a vertical section of a spiral univalve (Rostellaria), filled 
with the soft parts of the animal, converted into molluskite. 
Upon analysis this substance is found to contain a large 
proportion of animal carbon.* The rocks of firestone at 
Southbourne, on the Sussex coast, are mottled with brown 
molluskite and hard amorphous concretions, consisting of 
carbon and phosphate of lime, mixed with sand and other 
extraneous matter. Casts of shells, of the genera Venus, 
Arca, &c., entirely composed of the same kind of materials, 
are also abundant in those rocks. The lowermost bed of 
Galt, at its line of junction with the Green Sand beneath, at 
Folkstone, and in many other localities, is largely composed 
of similar matter, resembling in appearance the fossils called 
Coprolites, hereafter described. The outer chamber of the 
Ammonites and other shells, so abundant in the Galt, are 
often filled with this substance. But the most interesting 
deposit of molluskite is in the Kentish Rag of Mr. Bensted’s 
quarry, near Maidstone. This phenomenon had not escaped 
the notice of that intelligent and accurate observer, who 
liberally placed at my disposal numerous shells, particularly 
* Some of this molluskite has, at my request, been analyzed by 
Mr. Rigg, who obliged me with the following remarks :—“ After 
removing the lime by means of hydrochloric acid from ten grains of 
this substance, there remained 1.2 grain of dark powder, which gave, 
by analysis with oxide of copper, .16 of a cubic inch of carbonic acid, 
and a small portion of nitrogen. On subjecting to the same kind of 
analysis two grains of the darker body, without previously acting 
upon it by any acid, .054 of a cubic inch of carbonic acid was 
obtained ; so that from these results there is no doubt but the darker 
portion of the molluskite contains about .85 per cent. of its weight of 
carbon in an organized state.” 
VOL. I. FF 
