THE KAIiTlI. 1G9 



preserves it in its present state of salubrity ; and this very pro- 

 Dably, by dashing and breaking in pieces the rudiments, if I may 

 so call tbeni, of the various animals that would otherwise breed 

 there, and putrefy. 



There are some advantages, however, whicn are derived from the 

 saltness of the sea. Its waters being evaporated, furnish that 

 salt which is used for domestic purposes ; and although in some 

 - places It is made from springs, and in others dug out of mines, 

 yet the greatest quantity is made only from the sea. That 

 which is called hay salt, (from its coming to us by the Bay of 

 Biscay,) is a stronger kind, made by evaporation in the sun ; 

 that called common salt, is evaporated in pans over the fire, and 

 is of a much inferior quality to the former. 



/.nother benefit arising from the quantity of salt dissolved in 

 the sea is, that it thus becomes heavier, and consequently more 

 buoyant. JMr Boyle, who examined the difference between sea- 

 water and fresh, found that the former appeared to be about a 

 forty-fifth part heavier than the latter. Those, also, who have 

 had opportunities of bathing in the sea, pretend to have experi- 

 enced a much greater ease in sw imming there than in fresh water. 

 However, as we see they have only a forty-fifth part more of 

 their weight sustained by it, I am apt to doubt whether so 

 minute a difference can be practically perceivable. Be this as it 

 may, as sea-water alters in its weight from fresh so it is found 

 also to diffLT from itself in different parts of the ocean. In ge- 

 neral, it is perceivable to be hea\aer, and consequently Salter, 

 the nearer we approach the Line.' 



But there is an advantage arising from the saltness of the 

 waters of the sei, much greater than what has been yet mention- 

 ed; which is, that their congelation is thus retarded. Some 

 indeed have gone so far as to say, that sea-water never freezes ;' 

 but this is an assertion contradicted by experience. However 

 it is certain, that it requires a much greater degree of cold to 

 freeze it than fresh water ; so that while rivers and springs are- 

 seen converted into one solid body of ice, the sea is always fit 

 for navigation, and no way afiected by the coldness of the seve- 

 rest wnter. It is, therefore, one of the greatest blessings wt 

 derive from this element that, when at land all the stores of 



2 Phil. Trans, vol. ii p. "2!'7. 3 Macrubiaa. 



