1. A sufficiently approximate idea as to the hardness of a water by carbonate of lime may be obtained by half filling a test tube with the water and gradually heating to boiling over the spirit-lamp. If the water is very hard a turbidity will be perceptible on looking through the tube. This turbidity shows the presence of lime in considerable quantity. As lime, however, may also be present without being discerned by this test, proceed to apply another.

2. The addition of a small quantity of slacked lime dissolved in water, containing bicarbonate of lime, produces a white precipitate.

3. Add a few drops of a solution of oxalate of ammonia to water in test-tube. If carbonate of lime be present, the water will show after a little while a clouded or milky appearance, and in a few hours a white precipitate will be found at the bottom of the tubes. If this appearance takes place before, and not after a short boiling of the water, it is a proof of the presence of free carbonic acid; but if it takes place also after the boiling, then it must be carbonate of lime.

4. Pure lime in solution may be discovered by adding one or two crystals of oxalic acid to the water to be tested. A milky deposit shows lime.

For Magnesia

To test water for magnesia, heat it to the boiling point and add, on the point of a knife, a little carbonate of ammonia and some phosphate of soda. If magnesia be present, it will be deposited on the bottom of the vessel.

For Sulphate Of Lime

1. After adding a few drops of a solution of nitrate of baryta to the test-tube the presence of sulphate of lime is in-dicated by a milky appearance, and by the formation of a white precipi-tate. If the cloud remains at the top, it indicates the presence of sulphuric acid. 2. Sulphate of lime is deposited from water in the form of a white precipitate by the addition of chloride of barium. The precipitate is not soluble in nitric acid.