63 
of a fair sample of the bulk of the dark part of the specimen. 
This gave 
Sulphates of potash and soda 1-62 
Carbonate of lime 45-61 
Carbonate of magnesia 26-91 
Bisulphide of iron 1T65 
Oxides of iron 13-578 
Silica 0-23 
Moisture v . . . . 0.402 
The minutest vessels of the central axis and the internal 
radiating cylinder of the plant, with their finely striated sides, 
were preserved nearly as perfectly as in the living plant, 
without affording evidence of disarrangement from pressure 
or chemical change. 
From the position where the calcareous nodules occur, 
namely in the middle of the seam of coal, they must have 
have been formed when the coal was in a soft and pulpy 
state and in the same shape and condition in which they are 
now found, something similar to such nodules in a peat bog 
of the present day. Instances have been known of hazel nuts 
placed in a damp calcareous deposit having had all their 
kernels removed and replaced by carbonate of lime while the 
woody portion of the nutshell remained little altered, but in 
this case the form of the starchy granules and original cellular 
tissue had not been preserved. 
From the analysis previously given it is evident that the 
waters in which the nodules were formed contained a consi- 
derable amount of sulphuric acid, probably as much as would 
act on the cellular tissue and woody fibre of the vegetables so 
as to convert them into colloids. If this be assumed to be 
the case, then we might by the laws of liquid diffusion given 
by Mr. Thomas Graham, F.R.S., Master of the Mint, in his 
valuable paper printed in the Philosophical Transactions for 
T86 1 , suppose that the crystalloids now forming the light 
coloured cylinder in the middle of the specimen could have a 
