considerable masses—up to 731 carats, according to E. Boutan. It has here been found enclosing Diamond.
The
origin of Diamond has for ages been a point of dispute, and innumerable
theories have been advanced dealing with the subject. One of the
difficulties is that in most cases the mineral is not found in situ, but only in alluvial deposits, either recent or ancient, containing the debris of many different rocks, as a rule.
The
earliest definite theory advanced was that of Brewster, who held the
mineral to be formed by the consolidation of a resinous substance
resulting from plant life. Jameson held it to be a separation product
from sap. Later a large number of scientists regarded it as certain
that the carbon came from the decomposition of organic matter, either
vegetable or animal, but they were divided as to the means by which
carbon in its ordinary organic combinations could be transformed into
the allotropic form Diamond, some holding that a very bigh temperature
was necessary, and others that the change could be accomplished at
comparatively low temperature. Of the latter group, D'Orbigny and
Wohler were some of the first thinkers. Later, when it became known
from experimental work that Graphite, and not Diamond, was formed by
the action of great heat on amorphus carbon, there were several who
held to the low temperature theory, among these G. Bischof. J. D. Dana,
of the former group, believed it to result from the alteration of
carbonaceous matter by processes then invoked to account for the
metamorphism of rocks. Parrot believed the change to occur from the
sudden cooling of highly heated organic matter, and Carvill Lewis, from
a study of the South African deposits, came to the conclusion that the
