Alkaline carbonates soften water, decompose all the earthy salts (calcareous and magnesian carbonates, sulphates, and chlorides) and precipitate the earthy matters. They leave, however, in solution, an alkaline salt, but which does not communicate to water the property of hardness. Sea-water includes the waters of the ocean and of those lakes, called island seas, which possess a similar composition. The Dead Sea, however, varies so much from ordinary sea-water, as to rank amongst mineral waters. The quantity of solid matter varies considerably in the waters of different seas, as the following statement proves

10,000 parts of water of Solid constituents. the Mediterranean Sea, contain - - - - 410 grs. English Channel,

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C At the Island of Fohe, ". " Norderney, -

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- 380 " 345 " 342 " Uerman Ocean < | In the Frith of Forth, - - - 312 " I At Ritzebuttle, - - - 312 " At Apemalle, in Sleswick, - 216 " At Kiel, in Holstein, - - - 200 " Baltic Sea At Doberan, in Mecklenbergh, At Travemunse, At Zoppot, in Mecklenbergh, .... -

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- 168 " 167 " 76 " At Carshamm, - - - - - 66 " The average quantity of saline matter in sea-water is 3| per cent., and its specific gravity about 1.0274. The composition of sea-water differs also in different localities. Iodine has been found in the Mediterranean sea. Action of Water on Lead. When lead is exposed to atmospheric air, the oxygen of the air combining with it, forms an oxide, while, at the same time the carbonic acid of the air, unites with it forming a thin white crust, which is the carbonate of