CHEMICAL AND PHYSICAL NOTES. 75 
sea-water below that of distilled water is found by addiny 0-04 to the 
number expressing the percentage by weight of chlorine in the same 
water. From these few remarks, it will be seen that the mutual 
interaction between ice, salt, and water must be taken into account 
in interpreting the results of the sea-temperatures of the Antarctic. 
Sea [ce as met with in Polar Scas.—The above law refers to ocean 
waters which contain not more than 4 per cent. of dissolved matter. 
In the course of a Polar winter the sea freezes to a thickness of 8 or 
10 feet, and in proportion as the ice gets thicker, the actions and 
reactions between ice and brine and salt and water become more com- 
plex, and the law of freezing is no longer so simple as that stated 
above. 
Sea ice, as it occurs in the Arctic ocean, has been described 
in great detail by Weyprecht, in a work * which should be included 
in the library of every Antarctic expedition, The TZegetthoff, which 
was Weyprecht’s ship, was beset in the pack in lat. 76° 18’ N., long. 
61° 17’ E, on August 13, 1872. Twenty-one months later she 
was still a prisoner in the pack, and had to be abandoned. During 
all these months there was no lack of time or opportunity to study 
sea-ice in all its forms and moods, and every line of Weyprecht’s 
book is of interest to the voyager in icy seas. The matter is treated 
quite objectively. First the different forms which the ice assumes 
and their origin are dealt with; then ice-pressure, of which the 
Tegetthoff had sufficient experience, and the nature of sea-ice in 
winter and in summer, are described. In winter we have the 
formation of the ice and its transformations under the combined 
influence of cold and varying pressure; in summer, unfortunately 
for the Zegetthoff, there was no opportunity of studying the dis- 
appearance of the ice, but its transformations under the influence of 
melting and varying pressure are described. After these detailed 
studies, we have a description of the motions of the ice and of the 
water as observed in North Polar regions, and speculations as to 
what may be expected to take place in regions not then visited. 
For the chemist and the physicist the following extracts, which 
describe the freezing of sea-water under severe cold, are of special 
interest : 
Page 55.—The author is here describing the ice which surrounded 
the Tegetthoff during the winter. Referring to the openings which 
occurred in it from time to time and without apparent reason, he 
says :— 
*<Die Metamorphosen des Polareises, von Karl Weyprecht. Wien, Moritz 
Perles, 1879. 
