k was thrust into the mass, it broke into
many-sided lumps of the size of a tennis-ball, which separated, and
fell apart in a heap, like assorted coals thrown from a scuttle,
though white instead of black. These were the curious glacier nodules,
"grains du glacier," or "Gletcherkoerne," characteristic of glacier ice
as contrasted with lake ice. This structure of the glacier ice is
peculiar to it, and is only made evident where the sun's rays
penetrate it and melt the less pure ice which holds together the
crystalline nodules. According to Dr. J. Young Buchanan, these nodules
are masses of ice crystals comparatively free from mineral matter,
whilst the water around them, which freezes less readily, contains
mineral impurities in solution. The presence of saline matter in
solution lowers, in proportion to its amount, the freezing-point of
the water. Accordingly, although frozen into one solid mass with the
nodules, the cementing ice melts under the heat of the penetrating
rays of the sun sooner--that is, at a lower temperature--than do the
purer crystalline nodules, and allows them to separate. It is owing to
this that the exposed surface of glacier ice is white and powdery,
disintegrated by the superficial heat, and forming a rough surface, on
which one can safely walk. Lake ice does not break up in this manner
under the sun's rays, but as it melts retains its smooth, slippery
surface. It is formed in water, and not from the cementing and
regelation of the powdery crystalline snow, as is glacier ice.

Pictures of the Rhone glacier published in the year 1820 and in the
eighteenth century show that in old days the terminal ice-fall did not
end abruptly in a narrowed "snout," as it does now, but spread out
into a very broad half-dome or fan-shaped, apron-like expanse, some
700 feet high and a quarter of a mile broad at the base. It was
considered one of the wonders of Switzerland, and was pictured in an
exaggerated way in travellers' books. In 1873, when I first drove down
the Furka road and saw the Rhone glacier, this wonderful, apron-like,
terminal expansion of the glacier was still in existence. It has now
completely disappeared. In those days, and for many years later, there
was only a mule-path over the adjacent Grimsel Pass, but now there is
a carriage road leading out of the Rhone glacier's basin northwards to
Meiringen, whilst the old-established Furka road, at the other side of
the amphitheatre, leads eastward to A