CHEMICAL AND PHYSICAL NOTES. 91 
which it ceased to freeze, it dilutes the brine, and raises its own 
melting point.* We see, then, that the grain of the glacier may be 
surrounded in summer by a relatively considerable envelope of water 
* The following passages from the writer’s paper on ‘Ice and Brines,’ pp. 143-146, 
explain this in greater detail. ‘“ All natural waters, including rain water, contain some 
foreign an usually saline ingredients. If we take chloride of sodium as the type of 
such ingredients, and suppose a water to contain a quantity of this salt, equivalent to 
one part by weight of chlorine in a million parts of water, then we should have a solu- 
tion containing 0°0001 per cent. of chlorine, and it would begin to freeze and to deposit 
pure ice at a temperature of — 0°-0001 C.; and it would continue to do so until, say, 
999,000 parts of water had been deposited as ice. There would then remain 1000 parts 
of residual water, which would retain the salt, and would contain, therefore, 0-1 per 
cent. of chlorine, and would not freeze until the temperature had fallen to — 0°°1 C. 
This water would then deposit ice at temperatures becoming progressively lower, until 
when 900 more parts of ice had been deposited, we should have 100 parts residual 
water, or brine, as it might now be called, containing 1 per cent. of chlorine and 
remaining liquid at temperatures above —1°-0 C. When 90 more parts of ice had 
been deposited we should have 10 parts of concentrated brine containing 10 per cent. of 
chlorine and remaining liquid as low as — 13° C. In the case imagined we assume the 
saline contents to consist of NaCl only, and with further concentration the cryohydrate 
would no doubt separate out and the mass become really solid. On reversing the 
operations, that is, warming the ice just formed, we should, when the temperature had 
risen to about — 13° C., have 999,990 parts of ice and 10 brine containing 10 per cent. 
of chlorine. Now, owing to the remarkable fact that pure ice in contact with a saline 
solution melts at a temperature which depends on the nature und the amount of the 
salt in the solution, and is identical with the temperature at which ice separates from a 
sulution of the same composition on cooling, the brine liquefies more and more ice at 
progressively rising temperatures, until, as before, when the temperature of the mass 
has risen to — 0°-1 C. it consists of 999,000 parts of ice and 1000 parts of liquid water 
containing 1 part of chlorine. Tbe remainder of the ice will melt at « temperature 
gradually rising from — 0°-1 to 0°°0 C. 
Water Conratninc 7 Parts CaLorine 1n 1,000,000. 
Temp. Water frozen. Ice formed. Brine remaining. Ice and Brine. 
°C. C.c. cc. C.c, Cis 
T Vi cn Vo v9 
— 0°07 99,000 107,979 1000 108,979 
— 9°10 99,390 1083 6 700 109,006 
— 015 99,533 108,561 467 109,02% 
— 0°20 99,650 108,687 350 109,037 
— 0°40 29,825 108,879 175 109,054 
“In this table are given the volumes occupied by the ice (with inclosed brine) formed 
by freezing 100,000 c.c. (at 0° C.) of a water containing chloride of sodium, equivalent 
to 7 grms. chlorine in 1,000,000 ce. (at 0° C.) 
“The plasticity of ice and the motion of glaciers receive a simple and natural ex- 
planation when we see, as in the table, that if the water from which this ice is produced 
contains no more than 7 parts of chlorine per million, it will in the process of thawing 
when the temperature has risen to —0°-07 C. consist to the extent of 1 per cent. of its 
maass of liquid brine or water. The water considered in the table is certainly not less 
free trom foreign ingredients than rain or snow. It follows, therefore, that a glacier in 
a climate where the temperature is for the greater part of the year above 0° OC. must 
have a tendency to flow, owing to the power of saline solutions to deposit ice and to 
dissolve it at temperatures below 0° C.” 
