The theory of
metamorphism was not established until the individual phases of the change
were followed step by step, and direct chemical experiments on the
difference in the fusion point, in the pressure and time of cooling, were
brought in aid of mere inductive conclusions. Where the study of chemical
combinations is regulated by leading ideas,* it may be the means of throwing
a clear light on the wide field of geognosy, and over the vast laboratory of
nature in which rocks are continually being formed and modified by the
agency of subterranean forces.
[footnote] *See the admirable researches of Mitscherlich, in the 'Abhandl.
der Berl. Akad.' for the years 1822 and 1823, s. 25-41; and in Poggend.,
'Annalen', bd. x., s. 137-152; bd. xi., s. 323-332; bd. sli., s. 213-216
(Gustav Rose, 'Ueber Gildung des Kalkspaths und Aragonits', in Poggend.,
'Annalen', bd. xli., s, 353-366; Haidinger, in the 'Transactions of the
Royal Society of Edinburgh', 1827, p. 148.)
The philosopohical inquirer will escape the deception of apparent analogies,
and the danger of being led astray by a narrow view of natural phenomena, if
he constantly bear in view the complicated conditions which may, by the
intensity of their force, have modified the counteracting effect of those
individual substances whose nature is better known to us.
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