46 CELESTIAL, ATMOSPHEKIC, AND 



others that the sea is a sweat of the Earth, resulting from 

 the heating of the Earth by the Sim.* Some said, according 

 to Aristotle, that, just as water percolating through ashes 

 becomes salt, so in the same way the sea was salt in conse- 

 quence of a mixture therewith of earthy substances.! They 

 were of opinion that rivers flowing into the sea carried into 

 it many earthy substances having various flavours, and, by 

 mingling with the sea-water, caused it to be salt.t This 

 explanation was rejected by Aristotle on the ground that, 

 if it were true, the rivers ought to be salt.§ 



When giving his own views explaining why the sea is 

 salt and why it remains so, Aristotle shows very clearly that 

 he was aware of the vast amount of evaporation due to the 

 solar heat, that it was fresh water which was thus raised 

 into the atmosphere, the salt water being left behind, and 

 that all this fresh water ultimately condensed and descended 

 to the earth or the sea. He knew also that the quantity 

 which descended varied in different places and at different 

 seasons, but he clearly asserts that, during certain definite 

 periods, all the evaporated water descended again. 1! 



After making many other statements, many of which are 

 uninteresting or apparently valueless, he says that, with 

 respect to the cause of the saltness of the sea, it is clear 

 from many indications that such saltness is due to a mixture 

 of something with the water. ^ Among the indications 

 which he gives, the following are worth reciting: — (1) water 

 which has percolated through the walls of a completely 

 closed wax vessel, immersed in the sea, is found to be fresh 

 or potable ; (2) the thickness or density of sea- water is so 

 much greater than that of river-water that merchant ships, 

 similarly laden, almost sink in the former but float in the 

 latter at a depth convenient for sailing ; and (3) eggs, even 

 when full, float in water made very salt by mixing saline 

 substances with it.** 



Aristotle, having proceeded so far, might perhaps 

 reasonably have been expected to conclude that the some- 

 thing mixed with the water of the sea was some saline 

 substance, but nowhere does he appear to do so. The 

 substance which he decided was mixed with the water was 

 that peculiar one, the dry exhalation, referred to so often 

 already. He says that some believed that the sea was 



* Meteorol. ii. c. 1, s. 4, ii. c. 3, s. 12. | Ibid. ii. c. 1, s. 5. 



I Ibid. ii. c. 3, s. 10. § Ibid. || Ibid. ii. c. 2, ss. 12-14. 



IT Ibid. ii. c. 3, ss. 22 and 35. ** Ibid. ii. c. 3, ss. 35-38. 



