238 
Sir William Dawson and Mr Carruruers. In the discussion 
of a paper read by Mr Weruerep before the Geological 
Society last year, Mr Carrutuers said: “‘ Seams of coal are 
the remains of forests that grew upon swampy ground, and 
were subsequently covered by clay.” Sir Wirzt1am Dawson, 
in his “Acadian Geology,” says: “The plants which have 
contributed the vegetable matter of coal are principally Sigil- 
larie, with Cordaites Ferns and Calamites. With these however 
are intermingled remains of most of the other plants of the 
period, contributing in an inferior degree to the accumulation 
of the mass.” Without in any way wishing to undervalue the 
great work done by these eminent men, it is necessary to under- 
* stand how they came to their conclusions ; bearing in mind that 
in a previous paper read to the Club mention was made of the 
connection of Cordaites with coal. 
Sir Witt1am Dawson’s method of examining the mineral 
was to submit pieces containing the tissue of a single plant to 
the action of boiling nitric acid, the residue being washed 
and submitted to microscopic examination. Mr CarrurHers 
obtained his information from certain mud-balls in the British 
Museum, said to have been derived from seams of coal in 
which Mr Carrutuers finds the remains of carboniferous forest 
growth. Mr Weruerep objects to both of these processes as 
giving unreliable results as to the nature of coal in general, 
and appeals to the evidence of recent bogs to show how future 
coal-deposits are accumulating at the present day. In a recent 
peat-bog, the vegetation which constitutes the mass of the bog 
is formed by the peat-mossess (Sphegnacee). Growing on the 
top, however, are Conifers and other trees.. Such a bog being 
submerged, would pass from peat to lignite, and thence to coal; 
such coal would contain the trunks of trees; but were it thence 
to be concluded that the coal owed its origin to the trees, a 
very erroneous idea would be formed. Mr Weruerep objected 
to Sir Wi11am Dawson’s method of selecting a portion as 
representative of the mass, and likewise to the treatment in 
boiling nitric acid, which must ensure loss and destruction of 
substance and structure. 
ou _—— — ee ——— 
