e mixed soil being very porous, and causes the water to
rise: when the tide falls, the fresh water sinks also. _A sponge full of
fresh water placed gently in a basin of salt water, will not part with
its contents for a length of time if left untouched_, and the water in
the middle of the sponge will be found untainted by salt for many days:
perhaps much longer if tried."--Vol. i. p. 365. In a perfectly
motionless medium the experiment of the sponge may no doubt be
successful to the extent mentioned by Admiral Fitzroy; and so the
rain-water imbibed by a coral rock might for a length of time remain
fresh where it came into no contact with the salt. But the disturbance
caused by the tides, and the partial intermixture admitted by Admiral
Fitzroy, must by reiterated occurrence tend in time to taint the fresh
water which is affected by the movement: and this is demonstrable even
by the test of the sponge; for I find that on charging one with coloured
fluid, and immersing it in a vessel containing water perfectly pure, no
intermixture takes place so long as the pure water is undisturbed; but
on causing an artificial tide, by gradually withdrawing and as gradually
replacing a portion of the surrounding contents of the basin, the tinted
water in the sponge becomes displaced and disturbed, and in the course
of a few ebbs and flows its escape is made manifest by the quantity of
colour which it imparts to the surrounding fluid.]

An idea of the general aspect of Ceylon will be formed from what has
here been described. Nearly four parts of the island are undulating
plains, slightly diversified by offsets from the mountain system which
entirely covers the remaining fifth. Every district, from the depths of
the valleys to the summits of the highest hills, is clothed with
perennial foliage; and even the sand-drifts, to the ripple on the sea
line, are carpeted with verdure, and sheltered from the sunbeams by the
cool shadows of the palm groves.

SOIL.--But the soil, notwithstanding this wonderful display of
spontaneous vegetation, is not responsive to systematic cultivation, and
is but imperfectly adapted for maturing a constant succession of seeds
and cereal productions.[1] Hence arose the disappointment which beset
the earliest adventurers who opened plantations of coffee in the hills,
on discovering that after the first rapid development of the plants,
delicacy and languor ensued, which were only to be corrected by
returning to the