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Previous Next The best candle and soap tips online! TECHNICAL TREATISE ON SOAP AND CANDLES. SOAP ANALYSIS. 369 contact with the liquid becomes white and opalescent, while the other remains transparent. Soap in contact with warm water loses at first a part of alkali, water, and fatty substance; it becomes richer in solid acids and is less aqueous. Its transparency is as much greater as it contains less water and alkali; afterwards its solution in warm water will be slower if it contains more stearic than margaric acid, and more of this latter than oleic acid. Lastly, each kind of soap by its solubility in warm water, by the transparency and consistency of its aqueous solution, presents to the observer shades more easily seen by the aid of a comparative examination. After studying the characteristics of the aqueous solution of a soap, it is very easy to determine its composition by the following method: This process, which consists in measuring the constituent principles of a soap to ascertain its weight, is called saponimetry, by which the manufacturer may, in half an hour, test several specimens of soap, compare them, and select the best for his use. To operate according to this method, it is necessary to prepare beforehand two liquors, one which is acid, the other alkaline. These two liquors ought to be kept in ground-stoppered bottles. Preparation of the Normal Acid Liquor. Take Monohydrated sulphuric acid (66°) . . 189.84 grammes (6.64 ozs.). Distilled water same quantity. and add, after the cooling of the liquor, enough water to make one litre (2.1 pints) at the temperature of 15° C.(59° F.). 10 cubic centimetres (0.338 fluidounce) of normal acid contain 1.8984 grammes (29.29 grains) of monohydrated sulphuric acid, and are equivalent, in forming a neutral salt, to 1.2 grammes (18.5 grains) of soda, or 1.825 grammes (28.16 grains) of potash. The equivalent of monohydrated sulphuric acid is 612.5 (SO3, 500 + HO, 112.5 = 612.5). The equivalent of soda is 387.17. The weight of sulphuric acid necessary to form a neutral salt with soda (1.2 grammes), is known by NaO SO:iHO NaO SO3HO 387.17 : 612.5 : : 1.2 : = 1.8984 The weight of this acid, which has to be mixed with a sufficient quantity of water to form one litre (2.1 pints) of acid liquor, is known by 1.8984 grm. x 1000 c. c. 1on o. w a = 189.84 grammes (6.64 oza.). To prepare 50 cubic centimetres of acid liquor, we have Preparation of the Normal Alkaline Liquor. Pure and dry carbonate of soda . . 41.016 grammes (1.44 ozs.). Distilled water enough to dissolve the carbonate and obtain one litre of alkaline liquor at a temparature of 15° C. (59° F.). 50 cubic centimetres (1.69 fluidounces) of this liquor ought to contain 1.2 grammes (18.5 grains) of soda, a weight represented by 2.0523 grammes (31.66 grains) of carbonate of soda. To ascertain the weight of the dry carbonate of soda which ought to represent 1.2 grammes of soda to saturate 1.8984 grammes (29.3 grains) of monohydrated sulphuric acid contained in 10 cubic centimetres (0.33 fluidounces) of the normal acid, knowing that 612.5 of monohydrated acid saturates 662.18 of carbonate of soda (NaO 387.17 + CO2 275=662.17), we have SO.fHO 612.5 NaO,CO2 662.17 SO3HO 1.8984 Na0CO2 = 2.0523 We find 2.0523 grammes of carbonate of soda without water, representing 1.2 grammes of soda which, dissolved in a sufficient quantity of water, ought to give 50 cubic centimetres of alkaline liquor at a temperature of 15° 0. (59° F.). The weight of carbonate to dissolve in a sufficient quantity 370 TECHNICAL TREATISE ON SOAP AND CANDLES. SOAP ANALYSIS. 371 of distilled water to obtain one litre of alkaline liquor is known by 2.0523 grms.x 1000 c.c. 50 c. c. = 41 046 grammes (1,44 0Zi) These normal liquids are used in— SAPONIMETRY. Soaps Composed of Solid and Liquid Fatty Acids.—The normal acid and the alkaline liquor being prepared, the question is to determine with rapidity the weight of the fatty matter, the alkali, and the water, without being obliged to use the balance. To obtain this result, take a graduated glass tube of a capacity of 50 cubic centimetres (1.69 fluidounces) divided into 100 parts (alkalimetry), to which a cork is adapted. Introduce into it 10 cubic centimetres (0.33 fluidounce) of normal acid. This acid must be carefully measured. Afterwards, add to it 20 cubic centimetres (0.66 fluidounce) of spirit of turpentine carefully measured; then weigh 10 grammes (0.35 ounce) of soap divided into very thin shavings which is introduced into the tube ; cork the tube;.stir for a few minutes until the soap is dissolved and then let it rest. A quarter of an hour is sufficient to have a complete separation of the turpentine, of the dissolved fatty matter, and of the water.* The heaviest part, which is water, sulphate of soda, and sulphuric acid, falls rapidly to the bottom of the tube; the lightest part formed with turpentine and fatty matter occupies the upper part; lastly, a layer formed of an albuminous or animal matter occupies the middle. This latter layer, which is neither fatty matter nor water, is sometimes voluminous enough to occupy the whole of the capacity of the tube containing the normal acid. A slight agitation is sufficient to collect it into a very thin * The solution of the fatty matter in the turpentine takes place -without dilatation or contraction of the volume ; it is the same for the mixture of the normal acid with the water. Previous Next
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