4388. To Test the Hardness of Water

4388. To Test the Hardness of Water. Hard water contains more or less carbonate of lime; the presence of this substance in waters is tested thus : Soap, or a solution of soap in proof spirit, mixes easily and perfectly with pure water, but is curdled and precipitated in water containing carbonates, chlorides, or sulphates. The degree of hardness of water depends on the amount of carbonate of lime held in it in solution, and is ascertained as follows: Dissolve 1 drachm finest white soap in 1 pint proof spirit; so adjust the strength (if not already so) that exactly 32 measures are required to be added to 100 measures of the standard solution of chloride of calcium (see No. 4786 (Solution of Chloride of Lime)), before a lather can be produced. Every measure of this test solution of soap and alcohol, which is required to produce the same effect on 100 measures of a sample of hard water, represents 1/2 grain of carbonate of lime or 1/2° of hardness; 2 measures equal 1° of hardness or 1 grain of carbonate per gallon, etc..

4389. To Test the Purity of Borax

4389. To Test the Purity of Borax. Its strength is best ascertained by the quantity of sulphuric acid required to neutralize a given weight of borax. (See Alkalimetry.) The impurities in borax are common salt and alum, which are mixed with it to lower the value.

Common salt may be detected by a solution of the borax in hot water yielding with nitrate of silver a curdy white precipitate which is soluble in ammonia; this must be distinguished from the white pulverulent precipitate of borate of silver which will be thrown down from pure borax.

The presence of alum is determined by addition of ammonia water to a solution of the borax giving a bulky white precipitate.

4390. To Test the Purity of Musk

4390.    To Test the Purity of Musk. Musk is often largely adulterated with dried blood, the presence of which may be detected by the inferiority of the odor; by an assay for the iron contained in the blood; or by microscopic examination. The ashes left after burning pure musk are neither red nor yellow, but grey, and should not exceed 6 per cent, of the amount burned.

4391. To Test the Purity of Ambergris

4391.    To Test the Purity of Ambergris. From the high price of the genuine ambergris, it is very frequently adulterated. When quite pure and of the best quality it is nearly wholly soluble in hot alcohol and ether, and yields about 85 per cent, of the odorous principle (ambreine). It is also easily punctured with a heated needle, and on withdrawing it not only should the odor be immediately evolved, but the needle should come out clean, without anything adhering to it.

4392. To Test Diamonds

4392.     To Test Diamonds. If you have a doubtful stone, put it into a leaden or platinum cup, with some powdered fluor-spar and a little oil of vitriol; warm the vessel over some lighted charcoal, in a fireplace, or wherever there is a strong draught to carry away the noxious vapors that will be copiously evolved. "When these vapors have ceased rising let the whole cool, and then stir the mixture with a glass rod to fish out the diamond. If you find it intact it is a genuine stone; but if it is false it will be corroded by the hydrofluoric acid that has been generated around it. A small paste diamond would disappear altogether under the treatment. This test is given by Massimo Levi, an Italian chemist.