202 Prof. W. King on Oceanic Sediments, and 
ginia, assuming that at one time they were like the Levant 
mud, in which there is generally an admixture of calcareous 
and siliceous organisms *. 
There are certain facts in geology which show analogous 
changes effected by the agency of carbonic acid: the most 
striking that occurs to me is the conversion, by means of this 
solvent, of beds of argillaceous limestone (Carboniferous) into 
highly aluminous rotten-stone, in Derbyshire and Glamorgan- 
shire. Nevertheless there are some grounds for refusing to 
look upon the “ red-clay”’ basins as so many Upas valleys. 
If carbonic acid destroyed all the shell-structures carried into 
them, the water would necessarily become charged with bi- 
carbonate of lime in solution; but from the various analyses 
hitherto made of sea-water, the quantity it contains of this 
salt appears to be very small compared with the amount of 
sulphate of lime. Carbonic acid may be the agent; but I am 
more in favour of sulphuric or rather sulphurous acid, con- 
sidering that such is not unlikely to be produced by the oxida- 
tion of sulphuretted hydrogen, derived from the decomposi- 
tion of organic matter—also the presence of its decomposing 
agent (oxygen), as determined by Messrs. Lant Carpenter 
and Buchanan, in the depths of the ocean f. 
Subjected to the action of sulphurous acid, the substance of 
all calcareous shells in a dead condition would be ultimately 
converted into soluble sulphate of lime, with liberation of car- 
bonie acid ; and thus the ocean would be perpetually supplied 
* Transactions of the Manchester Literary and Philosophical Society, 
‘1847. It must not be overlooked that the siliceous organisms which 
occur in the foraminifer-ooze in appreciable proportion have likewise for 
the most part disappeared in the red clay, through the action of some 
dissolving agent. Crystals of quartz, from Zinnwald, are not uncommon 
with their planes corroded and deeply excavated in places originally occu- 
pied by oligist—showing that the silica has been in some way removed 
by the action of a ferric oxide; the fact is of some significance in con- 
nexion with the disappearance of the siliceous organisms from the red 
clay. I may add that Mr. H. J. Carter has called attention to the rapid 
wasting or decay which siliceous (also calcareous) spicules of sponges 
undergo in his cabinet, whether mounted or unmounted, also in living 
specimens (see Ann. & Mag. Nat. Hist. 1878, vol. xii. pp. 456,457). This 
destruction appears to be due to solvent action of another kind. 
+ I have had some experience of the presence of sulphuretted hydrogen 
in the ocean during a strong gale of three days’ duration on the west side 
of the Doggerbank, while on one of my dredging-expeditions, some thirty 
years ago. The agitation of the sediment at the depth of about forty 
fathoms by the heavy seas caused so much of this gas to rise to the 
surface that my watch, a silver one, became quite blackened by its 
action. 
{ When Bischof wrote his ‘Chemical and Physical Geology’ very 
little was known respecting the abundance of calcareous organisms at 
the bottom of deep oceans. Fixing his attention on the vast amount of 
