liEVAN — ON THE ANTHRACITE-COAL. 
79 
In 100 parts. 
Bitu- 
Rliymney — 
Big Vein . . . 
Ras-las or Bydellog 
Yard Vein . . 
Four Foot Coal 
Red Coal . . 
Carbon. 
82.33 
82.79 
80.92 
80.15 
84.25 
minous 
Matter. 
13.17 
12.96 
16.20 
15.10 
12.75 
In 100 parts. 
Bitu- 
Carbon. minous 
Matter. 
. . . 88.87 9.00 
. . . 89.29 6.68 
. . . 91.86 6.14 
6. Dowlais — 
Big Vein . . . 
Ras-las . . . , 
Upper Four Foot 
Cwm Cenol . . , 
Little Vein . . , 
7. Cyfartha — 
Big Vein . . 
Cwm-ddu . . 
. 85.00 11.87 
. 85.02 13.23 
. 85.75 12.75 
. 88.63 9.74 
. 86.90 11.72 
. 90.28 7.97 
. 88.78 9.22 
CyfartJia, cont. — 
Cwm-mwyn . 
Crom-y-gls . 
Gelly-deg . 
8. Birwain — 
Big Vein . . . 
Four Foot Coal . 
10. Swansea Valley— 
Big Vein . . 
Brass Vein . . 
Black Vein . . 
. 88.94 7.18 
. 90.26 7.86 
. 92.89 5.61 
. 92.46 6.04 
. 93.14 5.36 
9. Onhvyn and Neath Valley — 
Eighteen Foot Coal . 91.43 6.24 
Nine Foot Coal . . 93.12 5.22 
The next point is rather a qucestio vemta, viz. the causes which have 
produced anthracite. Many geologists consider the causes to be 
purely chemical, and that they are in action at the present time, — 
causes involving the existence of an immense internal heat, which is 
gradually changing the whole basin. Dr. Schafliaeutl considered that 
the anthracite was altogether a distinct and separate formation ; that 
it never was bituminous, but that it derived its distinctive features 
from a different chemical composition of the original vegetable 
matter. I cannot myself agree with either of these theories ; nor do 
I consider that the cause of the change was chemical, or that it is 
still in progress. With the second hypothesis I still less agree ; for 
under the seams of anthracite-coal we find the same underclays as 
underlie the bituminous seams, proving, at all events, that the same 
conditions of soil and growth existed in one as the other ; added to 
which, I have frequently found in the anthracite fossil plants identical 
with those of the bituminous coal, the only difference being that the 
former appear to have been subjected to greater heat. 
The facts,, too, which I have stated about the gradual commencement 
at Rhymney, a^id the subsequent increase of the anthracitic condition, 
do not seem to be compatible with the totally distinct chemical opera- 
tions. It is generally stated that the proximity of trap-rocks, <fec. is 
a common cause of the change to anthracite. In the South Wales 
basin there are no visible trap-rocks (except in Pembrokeshire, where 
they have nothing to do with the present question), but, nevertheless, 
I cannot help imagining that the changes have been caused by trap- 
