organisms it might contain, we put it into jars to settle, it remained
for days in suspension, giving the water very much the appearance and
colour of chocolate.

"In indicating the nature of the bottom on the charts, we came, from
experience and without any theoretical considerations, to use three terms
for soundings in deep water. Two of these, Gl. oz. and r. cl., were very
definite, and indicated strongly-marked formations, with apparently but
few characters in common; but we frequently got soundings which we could
not exactly call '_Globigerina_ ooze' or 'red clay,' and before we were
fully aware of the nature of these, we were in the habit of indicating
them as 'grey ooze' (gr. oz.) We now recognise the 'grey ooze' as an
intermediate stage between the _Globigerina_ ooze and the red clay; we
find that on one side, as it were, of an ideal line, the red clay
contains more and more of the material of the calcareous ooze, while on
the other, the ooze is mixed with an increasing proportion of 'red clay.'

"Although we have met with the same phenomenon so frequently, that we
were at length able to predict the nature of the bottom from the depth of
the soundings with absolute certainty for the Atlantic and the Southern
Sea, we had, perhaps, the best opportunity of observing it in our first
section across the Atlantic, between Teneriffe and St. Thomas. The first
four stations on this section, at depths from 1,525 to 2,220 fathoms,
show _Globigerina_ ooze. From the last of these, which is about 300 miles
from Teneriffe, the depth gradually increases to 2,740 fathoms at 500,
and 2,950 fathoms at 750 miles from Teneriffe. The bottom in these two
soundings might have been called 'grey ooze,' for although its nature has
altered entirely from the _Globigerina_ ooze, the red clay into which it
is rapidly passing still contains a considerable admixture of carbonate
of lime.