of sea waters, in different parts of the ocean , &c. 181 
C£ porous, and consists of spicular shoots or thin flakes, which 
detain within their interstices the stronger brine ; that it can 
therefore never yield pure water; though if the strong brine 
be first suffered to drain off slowly, the loose mass which re- 
mains will melt into a brackish liquid/’ &c. This statement 
however seems to have been founded rather upon results 
obtained from the artificial congelation of sea water, than 
from the examination of the sea ice itself ; for it will be 
seen, by a reference to Table IV., that this ice yielded, in 
every instance, water considerably purer than we commonly 
find spring water, or even river water.* Thus, for instance, 
water from young ice scarcely exceeding half an inch in 
thickness (Table IV. spec. 58), was found to have a specific 
gravity of only 1000,15; and yet Lieutenant Parry, by 
whom this specimen was taken up and brought home, told 
me that he had not used the precaution of wiping the ice 
before he suffered it to melt, a circumstance which is more 
than sufficient to account for the minute quantity of saline 
matter which it contained. 
It appears therefore well established that sea water, when 
in the act of passing to the state of ice, parts with the whole, 
or nearly the whole of its salt to the lower and denser strata ; 
and it may be inferred also from several of the results men- 
* I found the specific gravity of the water of the Thames, taken from a large 
cistern in Lombard-street, 1000,43. The water was quite clear ; and, from the 
cistern being filled at different periods of the tide, afforded a good average of that 
water at London Bridge. I found the specific gravity of the water of the New River, 
taken from a cistern in my own house, 1000,52 ; and I was rather surprised to find 
that the specific gravity of a specimen of spring-water, from a well in Russell square, 
was only 1000,17. 
