Curiosities of Science. 179 



HOW TO ASCEKTAIN THE SALTNESS OF THE SEA. 



Dry a towel in the sun, weigh it carefully, and note its 

 weight. Then dip it into sea-water, wring it sufficiently to 

 prevent its dripping, and weigh it again ; the increase of the 

 weight being that of the water imbibed by the cloth. It should 

 then be thoroughly dried, and once more weighed ; arid the ex- 

 cess of this weight above the original weight of the cloth shows 

 the quantity of the salt retained by it ; then, by comparing 

 the weight of this salt with that of the sea- water imbibed by 

 the cloth, we shall find what proportion of salt was contained 

 in the water. 



ALL THE SALT IN THE SEA. 



The amount of common Salt in all the oceans is estimated 

 by Schafhautl at 3,051,342 cubic geographical miles. This 

 would be about five times more than the mass of the Alps, and 

 only one- third less than that of the Himalaya. The sulphate of 

 soda equals 633,644*36 cubic miles, or is equal to the mass of 

 the Alps; the chloride of magnesium, 441, 811 '80 cubic miles; 

 the lime salts, 109,339*44 cubic miles. The above supposes the 

 mean depth to be but 300 metres, as estimated by Humboldt. 

 Admitting, with Laplace, that the mean depth is 1000 metres, 

 which is more probable, the mass of marine salt will be more 

 than double the mass of the Himalaya. Silliman's Journal, 

 No. 16. 



Taking the average depth of the ocean at two miles, and 

 its average saltness at 3 5 per cent, it appears that there is salt 

 enough in the sea to cover to the thickness of one mile an area 

 of 7,000,000 of square miles. Admit a transfer of such a quan- 

 tity of matter from an average of half a mile above to one mile 

 below the sea level, and astronomers will show by calculation 

 that it would alter the length of the day. 



These 7,000,000 of cubic miles of crystal salt have not made 

 the sea any fuller. 



PROPERTIES OF SEA-WATER. 



The solid constituents of sea-water amount to about 3| per 

 cent of its weight, or nearly half an ounce to the pound. Its 

 saltness is caused as follows : Rivers which are constantly flow- 

 ing into the ocean contain salts varying from 10 to 50, and 

 even 100, grains per gallon. They are chiefly common salt, 

 sulphate and carbonate of lime, magnesia,* soda, potash, and 

 iron ; and these are found to constitute the distinguishing cha- 

 racteristics of sea- water. The water which evaporates from the 



* It is the chloride of magnesia which gives that damp sticky feeling to the 

 clothes of sailors that are washed or wetted with salt-water. 



