76 CASH & HICK: FLORA OF THE LOWER COAL MEASURES. 
CHEMICAL COMPOSITION OF THE COAL BALLS. 
We have not yet subjected examples from the Coal Balls 
A consideration of the conditions under which the " coal 
balls " are found, leads us to concur with Mr. Binney, when 
he says, " So far as my experience extends, the occurrence 
of nodules in the coal is always associated with that of fossil 
shells in the roof, and therefore may probably be owing to 
the presence of mineral matter held in solution in water, and 
precipitated upon, or aggregated around, certain centres in 
the mass of vegetable matter now forming coal, before the 
bituminisation of such vegetables took place. No doubt 
such nodules contain a fair sample of the plants of which the 
seams of coal in which they are found were formed ; and 
their calcification was most probably due to the abundance 
of shells afterwards accumulated in the soft mud, and 
then decomposed, and now forming the shale overlying 
the coal. 
At present little is known of the process by which 
animal and vegetable bodies are decomposed, and the 
particles of which they were formed removed and exactly 
replaced by mineral matter. All observers have been struck 
with the wonderful perfection of the process by which the 
most microscopic parts of minute vessels and cells have been 
to a quantitative chemical analysis, but a qualitative examina- 
tion gives the following constituents : — 
PROCESS OF FOSSILISATION. 
