View report page

7
filth under the impression, when it was thought of at all, that water purified itself from its
contaminations in freezing." In Ure's Dictionary it is stated that " water in freezing really
rejects everything it may contain, even air, and hence solid ice is actually pure water further,
reference is made (loc. cit.) to Byron's knowledge of this fact ("Don Juan," 13th canto), and it is
stated that the old nobles of Russia, when they desired a more intoxicating drink than usual,
placed their wines or spirits in the ice of their frozen rivers, until all the aqueous portion was
frozen, when they drank the ardent fluid accumulated in the centre.
Several modern observers have experimented upon this property of water on assuming
the solid condition. Tyndall describes in "The floating-matter of the air" how in 1871 he
"sought anxiously and assiduously for water free from suspended particles," and how the thought
occurred to him of examining the liquid derived from the fusion of the most transparent ice. He
melted accordingly a block of ice, under conditions in which it was surrounded by moteless air,
and he subjected water from the very heart of the ice "to the scrutiny of the concentrated beam."
It proved to be probably the purest liquid "human eye had ever seen," but still it contained
"myriads of ultra-microscopic particles," and was as infectious as the water from any ordinary
tap." Abba1 refers to the experience of Arctic explorers—Nansen2 and the Duke of Abruzzi—who
describe the mineral salts of sea-water as being separated out like hoar frost upon the surface when
temperatures of from 30° to—40°C. are recorded, and who note the almost complete freedom
from saline taste of the water obtained from projecting ice-shafts " which have been exposed to the
rays of the sun during a summer, and are thus freed from the greater part of their salt."3 Again,
Abba describes the entire want of success attending an effort made in Turin to distinguish between
pure artificial ice and ordinary ice by the employment of pigments. Laboratory experiments
suggested the use of aniline dyes as a means of differentiating pure from impure ice, but on
applying this method on a large scale, the ice frozen from coloured water proved to be colourless.
Hey roth4 gives a full account of the various experiments made prior to the date of his
paper by way of historical introduction to his own work on the subject. Robinet, in Paris, found
the hardness of samples of ice-water materially less than that of the original water; Bolley,
in Zurich, and Bordoni-Uffreduzzi, in Turin, obtained somewhat similar results. Dufour concluded
that solid substances in solution were completely extruded by the ice-crystals themselves,
but remained to a greater or less extent entangled between individual crystals in the block of ice.
Rudorff held that the existence of finely divided foreign solid particles between the ice-crystals was
impossible, and that the ice-block therefore contained within it collections of saline solution.
This observer adduced the results of experiments with solution of magnesium-platinum-cyanide
(a salt which in the solid condition is coloured, but which yields a colourless solution) in support
of his views. Guthrie held that ice entered into combination with various solid matters, forming
"kryohydrates," having definite crystalline forms. Offer instanced as an objection to this
hypothesis the fact that on melting sea-water ice the first samples showed a considerable quantity
of salt, while later specimens, derived therefore from what was once the interior of the block,
proved to be almost pure water. Buchanan is cited as having obtained results confirmatory of
those of Offer. Heyroth refers further to the work Riidiger, Warren, Orlando Brown, Hills and
Nichols, Schelenz, and Prudden. The experiments of Pengra5 are also quoted by Heyroth, as
indeed they are by most writers on this subject. Pengra concluded that in freezing, ice caBts out
about 50 per cent, of the crystalloids, and only some 20 per cent, of the colloids contained in the
original solution frozen. This observer also experimented with bacteria (of these he found
90 per cent, removed); with coleps hirtus of stagnant pools (91'6 per cent, removed); with
paramcecium aurelia (93"3 per cent, removed); and with glaucoma scintillans from infusion of hay
(89 per cent, removed). He states that freezing does not kill these organisms, which multiply
rapidly. Further work on the chemical analysis of ice quoted by Heyroth relates to observations
by Fritzsche on coloured solutions, and to experiments on the freezing of milk by various observers:
this last-mentioned subject has received a good deal of attention of late years. Finally, Heyroth
refers to the application of freezing processes in the manufacture of pharmaceutical preparations
and in connection with wine and beer-making.
The Self-Purification of Ice from the Biological Standpoint.—A second reason for entertainment
of the opinion that freezing purifies water, and one which dates, of course, from growth of
knowledge concerning the germ theory of disease, is based upon belief in the destruction of living
organisms by prolonged exposure to cold. The earliest work of a precise character in this connection
was done by Fraenkel6.
A company had been formed in Berlin—" Krystalleis-Actien-Gesellschaft"—with the object
of manufacturing ice from distilled water, and this company had examinations made of the natural
ice sold in that city. The results were of a somewhat alarming character, and Dr. Karl Fraenkel
was directed to investigate the subject by Koch. Dr. Fraenkel indicated certain sources of error
which require to be guarded against in making bacteriological examinations of samples of ice, and as
a matter of fact, his results (which ranged from 21 to 8,400 organisms per c.c.) fell considerably
short of those obtained by the bacteriologist who had been employed by the artificial ice company.
1 Zeitschrift fur Hygiene und Infectionskrankheiten. Band 45, Hoft 2.
2 Nansen eays ("Farthest North," Vol. I., p. 220): " As soon as ice is formed in this temperature tho frost
forces it to throw out its salinity on the surface, and this itself freezes into pretty salt flowers resembling hoar-frost.',
3 " At our last camping place," eays Nansen, " it was impossible to find any ico which had boen exposed to
the cummer sun, and consequently freed from salt.—Ibid, Vol. II., p. 137.
4 Arbeiten aus d'm Kaiserlichen Gesundheitf suite, 1888.
Annual Reports of the State Board of Healtn of Michigan, 1882 and 1884.
Zeitschrift fur Hygiene, 1886.