So now remember that chalk is carbonate of lime, and that it is made up
of three things, calcium, oxygen, and carbon; and that therefore its mark
is CaCO(3), in Analysis's language, which I hope you will be able to read
some day.
But how is it that Analysis and Synthesis cannot take all this chalk to
pieces, and put it together again?
Look here; what is that in the chalk?
Oh! a shepherd's crown, such as we often find in the gravel, only fresh
and white.
Well; you know what that was once. I have often told you:--a live sea-
egg, covered with prickles, which crawls at the bottom of the sea.
Well, I am sure that Master Synthesis could not put that together again:
and equally sure that Master Analysis might spend ages in taking it to
pieces, before he found out how it was made. And--we are lucky to-day,
for this lower chalk to the south has very few fossils in it--here is
something else which is not mere carbonate of lime. Look at it.
A little cockle, something like a wrinkled hazel-nut.
No; that is no cockle. Madam How invented that ages and ages before she
thought of cockles, and the animal which lived inside that shell was as
different from a cockle-animal as a sparrow is from a dog. That is a
Terebratula, a gentleman of a very ancient and worn-out family. He and
his kin swarmed in the old seas, even as far back as the time when the
rocks of the Welsh mountains were soft mud; as you will know when you
read that great book of Sir Roderick Murchison's, _Siluria_.
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