PHYSICAL PROPERTIES OF ICE. 



649 



Port Kennedy. Latitude, 72° V N. ; longitude, 94° 15' W, 



1858, October 



1859, June 3. 



Surface ice formed at temperature +21° 

 „ „ „ (upper 6 inches) 



Specific gravity 1-0230 (30°) 

 1-0055 (30°) 



Salts in 100 Grains. No. 0. 



No.l. 



No. 2. 



No. 3. 



No. 4. 



No. 5, 



Sulphate and carbonate of lime - 0-5658 

 Sulphate of magnesia - - 0-3606 

 Chloride and bromide of magnesium 0-9766 

 Chlorides of sodium and potassium - 12-6192 



0-1170 0-1496 

 0-2316 0-2616 

 0-2470 0-2412 

 2-4158 2-7064 



0-1382 0-1126 

 0-2594 0-2762 

 0-2118 ' 0-2184 

 2-8212 j 2-7796 



0-1439 

 0-2296 

 0-3695 

 2-7825 



Solid contents - - ;14*4282 



3-0114 



8-3588 



3-4S06 



3-3868 



3-5255 



No. 5. 



Salts ; 100 grammes. 



Sulphate and car- 

 bonate of lime. 



Sulphate of magnesia 



Chloride and bro- 

 mide of magnesium. 



Chlorides of potas- 

 sium and sodium. 



Solid contents - 



0-0378 



0-0610 



0-0884 



0-3506 



0-0358 



0-0548 

 0-0698 



0-2474 



0-5378 



0-4078 



6. — Portion of ice taken from middle of perpen- 

 dicular block of ice— forming part of floe— after 

 being exposed in situ to a varying temperature 

 during eight months ; this floe had drifted 1,200 

 miles. Specific gravity, 1 • 005 (30°) . 



7.— Tn surface ice which was formed at tem- 

 perature of 21°, specific gravity, 1-0230. After 

 being exposed in situ to a temperature between 

 + 20° and —48° during nine months. Specific 

 gravity, 1-0055 (S0°). 



5. Physical Pkoperties of Ice. By Dk. J. Rae. (From the 

 Proceedings of the Physical Society.) 



If a saturated solution of salt is frozen, and the ice so formed 

 is fresh, it is evident that the salt that has been "rejected" must 

 be deposited or precipitated in a crystaUine or some other solid 

 form, because the water, if any, that remains unfrozen, being 

 already saturated, can hold in solution no more salt than it already 

 contains. 



Could not salt be obtained readily and cheaply by this means 

 from sea-water in cold climates ? 



During several long journeys on the Arctic coast, in the early 

 spring before any thaw had taken place, the only Avater to be 

 obtained was by melting snow or ice. By experience I found that 

 a kettleful of water could be obtained by thawing ice with a much 

 less expenditure of fuel, and in a shorter time, than was required 

 to obtain a similar quantity of water by thawing snow. Now, as 

 we had to can-y our fuel with us, this saving of fuel and of time 

 was an important consideration, and we always endeavoured to get 

 ice for this purpose. We had another inducement to test the sea- 

 ice frequently as to its freshness or the reverse. 



I presume that almost every one knows that to eat snow when it 

 is very cold, tends to increase thirst, whereas a piece of ice in the. 

 mouth is refreshing and beneficial, however cold it may be ; we 

 were consequently always glad to get a bit of fresh ice whilst at the 

 laborious work of hauling our heavy sledges -, yet with these strong 



