, 1877-12-29

blnes with it very readily. giving out heat
In the process. It is fond of sugar also,
40 we shall notice more particularly further
on. The eommonest of all acids in nature
is carbonic acid gas, the gas which we
know 80 we'll in soda-water. beer, cham
payne &c and which is difused 10 small
proportions through the entire atmosphere
and it is rot therefore surprising that the
commonest form of lime is that found in
union with carbonic acid, and which is
therefore called carbonate of lime. This
substance forms Almost the entire mass of
all llmest0nes, marls, %corals, SHELLS, the
sands OF our bays &C. OF much less i'm
portance 10 the combination of lime with
suIphuric acid, hence called sulphate oil ine.
This is the substance commonly known as
gypsum and plaster of Paris, and when
semitransrarent is called alabaster. A still
less important and rather rare combination is
that with d1oric acid. the ~Jquo'ate Of Cline, for
ming the beautiful Derbyshire spar, transpa-
rent, with bright purple or ora ngec oIoured
veins running through it, Blue john, as
it is called by the natives Of the county.
Another not very abundant. but very
widely difused form, in the combination
with phosphoric acid, called therefore
phosphate Of lime. This is the substance
which forms the bones of the higher ami
mails, and is therefore Of great interest to
ns. The soil everywhere contains it in
small quantities, from whence it passes into
grasses and the seeds of grasses, including
wheat, maize, gulnea-cOrn &c. 1t is there.
fore from the bread which we eat that our
system takes up the phosphate of lime TO
form our bones. and we perceive also the
value Il phosphate of lime as a manure
Tor lands intended to produce grain We
understand why homes, and bone-ash
should be sent IN ship-loads from BuenOs
Ayr,s aud Monte Video to fed the grain
fields of Europe and the United Safes.
From theso brief remarks on the
chemistry OF lime let US proceed tc answer
our question from the geological stand
point. Here we will conf IL our attention
TO the carbonate as by far the most impor-
tant OF all its combinations. We will ask
the patient reader to accompany us in
Imagination TO one of the hill-tOps in
Santa Cruz from thence to look down on
The shores of our beautiful isle. From the
height where we stand the waves of the
sea are reduced to an apparent ripple over
a deep blue or slate colOured surface. Off
the shore. and frequently at some distance
lIOm it. lines OF white foam divide the deep
ocean fiom shallow in-shore spaces tinted
with the most beautiful shades o. pale
green. The extent of these shadows is
very consid enable as more plainly appears
on the charts. II we take for example the
chart constructed by Captain Parsons, and
examine the space between the 100 fathom
line aud the shore we shall find that its
extent is greater tlan the whole Of Santa
Cruz Our survey shews therefore, that
this island is a lofty mountain rising from
the sea bottom. AMI having a considerable
portion OF its top cut off 10 form o plain
below the sea. In this submarine Santa
Cruz we may learn the origin of limestones.
Fret. let US examine the long fosming
lines. They are the reefs. They
do not rise like a wall from the sea
az some reader possibly supposes.
but are broad breaks formed mainly
Of living and dead corals, the spaces
filled 10 by q sand of which move
presently. The popular notion of coral
10 that it is built by an insect. Nothing
could be further from the truth. The
animal Of the coral no more builds than
we builds our bones : the carbonate of lime
- - 49, - II