1887.] Mr J. Y. Buchanan on Ice and Brines. 147 
Freezing Mixtures . — The results obtained in examining the 
melting-point of ice in saline solutions affords data for mixing 
freezing baths of any degree of cooling power. With chloride of 
sodium, for instance, a rough rule is to have such an amount of 
salt dissolved in the brine that the percentage of chlorine shall 
give the desired temperature in Centigrade degrees below the 
freezing-point. In my experiments in freezing sea-water in quanti- 
ties of 300 grammes, I usually made up the bath of 500 grammes 
pounded ice, 400 grammes water, and 45 grammes common salt. 
When mixed, the liquid contained about 4 per cent. Cl, and gave 
a temperature a little below - 4° C. In the course of an hour the 
liquid would contain 3 per cent, to 3*25 per cent. Cl, and the 
temperature have risen to - 3° C. By using such baths freezing 
operations can always be kept completely in hand. 
3. On the Distribution of Temperature in the Antarctic Ocean. 
By J. Y. Buchanan. 
(Abstract.) 
In the regions of the Antarctic Ocean where icebergs are numer- 
ous, and where in winter the sea- water freezes, the distribution of 
temperature in the deeper layers of water is peculiar. The facts are 
detailed in the Challenger Narrative (vol. i.). The general result 
of her observations went to show that, from the edge of the ice- 
pack, a wedge of cold water stretches northwards for more than 
12° of latitude, underlying and overlying strata at a higher tempera- 
ture than itself (p. 418). 
Although the conditions and facts likely to throw light upon the 
cause of this phenomenon are discussed, no satisfactory explanation of 
it is given. One important fact is noticed at p. 421 — “ The fact that 
the cold wedge above referred to extended north just as far as the 
icebergs did in March 1874 points to there being some connection 
between the temperature and the presence of melting icebergs.” It 
is well known that icebergs consist of land- ice, which is nearly 
pure frozen water, and melts in the air at 32° F. It was 
thought that the effect of immersion of such a substance in a 
medium having a temperature 3° F. lower than its melting-point 
would be to indefinitely preserve it — that, in fact, only the lower 
