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network of the crystallized water, and that the brine is
afterwards separated from the ice by the influence of variations ot
temperature. On the nature of this metamorphosis, two
different hypotheses have been propounded, which are
diametrically opposite to each other. Dr. Walker1 believed, that the
brine was squeezed out by the contraction of the ice by cold.
I think the impossibility of this hypothesis is sufficiently
proved in the foregoing chapter. In fact, sea-ice, which
contains any considerable part of its original saltness, is
expanded instead of contracted by the cold. Professor
Norden-skiold and Dr. Almqvist are prone to conclude, from their
observations during the winter 1878 at Pitlekaj, »that the
included brine slowly frets its way to the surface of the icefloe
where it was found on several occasions as a concentrated
overflow, which frequently deposited an efflorescence 2 of
crys-tal-needles consisting of an aqueous double salt of NaCl
and CaCl2. For this metamorphosis of the salt ice a
temperature near the melting point is necessarj^, as the peculiar
condition of the ice at those temperatures facilitates the
penetration of the bladders and drops of salt brine to the surface».
The general opinion thus seems to be, that the ice, even
if it separates from salt water, is chemically entirely free from
salt, although it may contain a slight quantity mechanically,
which adheres to it as salt-crystals or salt-solution. Although
combatted by at least one important authority, Dr. Buchanan
of the Challenger expedition, this opinion still predominates
among the majority of natural philosophers. One reason at
least speaks strongly in its favour, viz. the changeable amount
of salt, which is found in the ice. To those, who are prone
to limit the dominion of Chemistry to only combinations of
fixed proportions, the sea-ice never will appear to be anything
but a mechanical mingling of crystallized water with an
insignificant quantity, of sodium- and calciumsalts etc. I have
tried to do full justice to this point of view, just because it
is not my own. I do not pretend to see a well defined
chemical compound in every bit of floating sea-ice, but I think I
can show, that at the formation of the ice of the ocean forces
of quite another order, than the mechanical adhesion, are at
work to connect the salt with the ice.
1 Of the M’Clintock expedition 1857—59.
2 The efflorescence of salt crystals upon the surface of newly frozen
, ice was observed also by Wrangel and is minutely described by Wey-
precht a. 0.
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