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, 380 „ { At the Island of Fohe, 345 „ German Ocean { At the Island of Norderney, 342 „ { In the Frith of Forth, 312 „ { At Ritzebuttle, 312 „ At Apemalle, in Sleswick, 216 „ At Kiel, in Holstein, 200 „ Baltic Sea At Doberan, in Mecklenbergh, 168 „ At Travemunæ, 167 „ At Zoppot, in Mecklenbergh, 76 „ At Carshamm, 66 „ The average quantity of saline matter in sea-water is 3½ 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 lead_. This formation is accelerated by moisture, and by the presence of an unusual quantity of carbonic acid in the atmosphere. The same process goes on with still greater rapidity in pure running water. But if water be deprived of all its gases by ebullition, and excluded from contact with the air, the lead will not be acted upon If water, however, be exposed to the air, although all the gases have been expelled, a white powder will soon form around the lead, till, in the course of a few days, there is formed a large quantity of white, pearly scales, which partly float in the water, but are chiefly deposited on the bottom of the vessel. In 12 ounces of distilled water, contained in a shallow glass basin, loosely covered to exclude the dust, twelve brightly polished lead rods weighing 340 grains, will lose 2½ grains in 8 days, and the lead will show evident marks of corrosion; and this action will go on as long as the water is exposed to the air. While these changes are going on, a small quantity of lead will be dissolved, as may be shown by carefully filtering the water acidulating with a drop or two of nitric acid, and evaporating to dryness. Sulphuretted hydrogen is also a good test, occasioning, where lead is present, first a brown color, and subsequently a black precipitate.