Grammes. Chloride of sodium 25·704 Chloride of magnesium 2·905 Sulphate of magnesia 2·462 Sulphate of lime 1·210 Sulphate of potassa 0·094 Carbonate of lime 0·132 Silicate of soda 0·017 Bromide of sodium 0·103 Bromide of magnesium 0·030 Oxide of iron, carbonate and phosphate of magnesia,} Only and oxide of manganese } traces. ------ 32·657 ====== The water of the Mediterranean contains more salts than that of the ocean. The following are, according to M. Usiglio, who was one of a commission sent to examine the different kinds of salt water in the south of France, the component parts of one hundred gallons of Mediterranean water:-- lbs. Chloride of sodium 29·524 Chloride of potassium 0·405 Chloride of magnesium 3·219 Sulphate of magnesia 2·477 Chloride of calcium 6·080 Sulphate of lime 1·557 Carbonate of lime 0·114 Bromide of sodium 0·356 Protoxide of iron 0·003 ------ Total 43·735 ====== We conclude, from the quantity of sea salt contained in the water of the ocean, that, if it were spread over the surface of the globe, it would form a layer of more than thirty feet in height. The salt contained in sea water gives it a greater density than fresh water; its average specific weight is 1.027. The density of the water of the Mediterranean is, according to M. Usiglio, 1.025 when at the temperature of seventy degrees. But the saltness of the sea varies very much under the influence of a great many local circumstances, among which we must count principally currents, winds favourable to evaporation, rivers coming from the continents, &c.