1887 .] 
Mr J. Y. Buchanan on Ice and Brines. 
137 
In nature it is probable that the ice forming at the actual freezing 
surface does so at an almost uniform temperature, the local concen- 
tration produced by the formation of a crystal of ice being imme- 
diately eliminated by the mass of water below. In the interstices 
of the crystals there will be retained a weight of slightly concen- 
trated sea-water at least as great as that of the ice crystals. These 
retain the brine in a meshwork of cells, and, as the thickness of the 
ice covering increases, and the freezing surface becomes more re- 
mote, the ice and the brine become more and more exposed to the 
atmospheric rigours of the Arctic winter. The brine will continue 
to deposit ice until its concentration is such that, for example, the 
cryohydrate of NaCl is ready to separate out. It probably will 
separate out until it comes in conflict with, for instance, the chloride 
of calcium or the chloride of magnesium, which will retain some 
of the water, without solidifying, even at the lowest temperatures. 
At the winter quarters of the “Vega” brine was observed oozing 
out of sea- Water ice and liquid at a temperature of - 30° C. It 
was very rich in calcium and especially magnesium chlorides. In 
fact, it is probably quite impossible by any cold occurring in 
nature to solidify sea-water. 
b. Melting of pure ice in sea-water and other saline solutions. — A 
large number of experiments were made with solutions of concen- 
tration comparable with that of sea-water, and in one or two cases 
the experiments were extended to low temperatures and strong 
solutions. As a rule, from 50 to 100 grammes of solution, cooled 
to 0° C., were mixed with an equal weight of pounded ice, also at 
0° C. The thermometer used for all these determinations was one of 
Geissler’s normal ones, divided into tenths of a degree Centigrade ; 
and its zero-point was verified almost daily. Along with the 
thermometer, a pipette of suitable capacity was immersed in the 
beaker, and used with the thermometer for keeping the mass well 
mixed. Its upper aperture was closed with a small cork, which 
was removed from time to time to permit of some of the brine being 
sucked up and allowed to run back again. The inside of the 
pipette was thus kept constantly moistened with the slowly altering 
solution in the beaker. The temperature was read after very 
thorough mixing, and the sample thereupon immediately removed 
and preserved for analysis. 
