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Previous Next The best candle and soap tips online! are due to the combustion of the cxide of carbon; when they become more rare and less intense, it is a characteristic sign of the conversion of tho sulphate of soda into carbonate. Then slacken the action of the fire, for a higher elevation of temperature would cause the volatilization of an appreciable quantity of soda. Thus, when the luminous jets have diminished in intensity, draw off from the furnace the melted mass, which is received in square sheet-iron boxes five or six inches deep and three feet in diameter. These boxes are placed on rails and then put under sheds. After the soda is solidified and sooled, it is broken into large pieces and put into barrels. This sodii is generally in a melted and compact ruaas, particularly if the calcination has l>een pushed too far; but when the operation has been well conducted, its texture is not so compact, and sometimes is porous. It is preferred in this state, because by lixiviation it is more easy to deprive it of its soluble suits. When well prepared it resembles good Spanish soda ; it has a gray-ash coior, and is without smell. Its richness in pure alkali is generally constant, and depends essentially on the purity of the sulphate. If the sulphate contains only a few hundreths of undeeomposed salt, and is completely converted into carbonate by proper proportions cf chalk and charcoal, a soda is obtained which genenilly contains thirty-six per cent, of alkali. This soda, designated ty the name of soft soda, or alkaline soda, is specially used for the saponificatiou of oils in the fabrication of marbled and white soaps. As soon as the furnace is empty, load it again as at first with a mixture of Sulphate of soda, chalk, and charcml, and ojerate as we have indicated. The complicated reactions are thus explained: Under the influence of the charcoal, the sulphate of soda is transformed it to sulphuret, and at the same time, oxide of carbon is disengaged. Afterwards, the sulphuret of sodium and the carbonate of lime are mutually decomposed, and fro:a that decomposition result sulphuret of calcium and carbonate of soda; but as this reaction takes place at a temperature at 53 52 TECHNICAL TREATISE ON SOAPS AND CANDLES. which the carbonate of lime is decomposed, a part of the eoda is obtained in a caustic state. The proportion of caustic soda contained in the carbonate of soda, is ns much more considerable as the dose of charcoal has been increased, and that the mixture has been carried to a higher temperature. In a subsequent chapter we shall give the process for analyzing caustic alkalies. We think it will interest the reader to know the real cost of the substances used and produced, nnd we give below a. detailed table of the expense of manufacturing 20,000 lbs. of artificial soda in France. These numbers are very exact, and deserve full confidence. i?aw Materials. Sulphate of soda, 14,000 lbs, at fl.GO the 100 lbs. ... |994 00 Carbonate cf lime in powder, 14,700 lbs. at 6 centa the 100 lbs. . 8 82 Powdered CMI to traiuform the sulphate into carbonate, 7000 Iba. at 22 cents the 100 lbs. . . 15 40 Coal used aa & combustible about 3 tons 16 00 Other Expenses. 5 00 6 OC $275 2S Labor about 0 days General expenses Total Production.—2C,000 Iba. of crude aoda marking 36 alkali-metric degrees. "We see by the above table that the expense of manufacturing 20,000 lbs. of crude soda is $275.22, which puts the price of 100 lb«. at $1.88. Artificial Salted Soda.—Artificial salted soda is a mixture of soft soda and eommon salt. The proportion of salt varies from 25 to 40 per cent, of the weight of the soda. The use of this soda is necessary for the coetion of marble! Boaps. On account of the largepro|>ortion of salt it contains, it has tiie property of contracting the paste of the soap, and preventing its dissolution in the lye. Like soft artificial soda, it is prepared by tlie decomposition of the 6ulph;ite of MATERIALS USED IN THE MANUFACTURE OF SOAPS. 3oda by chalk and charcoal, only in the preparation of the sulphate, the quantity of sulphuric acid necessary to decompose the salt ia diminished, so that the eaiphate obtained contains from 30 to 40 per cent, of undecomposed salt. The proportion? generally employed are :— 2000 lbs. 1200 to 1400 lbs. Salt .... Sulphuric acid 50°, from The decomposition is conducted in the same mamier as for the soft soda. The sulphate obtained is calcined and mixed with the carbouate of lime and coal in the following proportions:— 3000 lbs. 1300 " 9000 " Sulphate of soda Carbonate of lime Coal in powder The substances are reduced to powder, and intimately mixed together. The decomposition takes place in the same manner as for the soft soda. Salted artificial soda has a less constant composition than soft eoda. Inde[>endent]y of the strong proportion of salt it contains, it is also more sulphuretted than the latter. This inconvenience is due to a more or less considerable portion of sulphuret of sodium, which has not been decomposed during the reaction, and is left mixed with the soda. This inconvenience may easily be remedied by cjmpletel/ transforming all the sulphuret into carbonate, by introducing an excess of chalk into the mixture. Thus, an oxi-sulphuret of calcium, very slightly soluble in cold water, is obtained, and by lixiviating the soda with cold water, a solution is obtained, which only contains traces of the sulphuret. It is evident, that under many circumstances the sulphuret night be troublesome, and such would be the case, if this soda were used in the fabrication and purification of fine soaps. But we must remark, that artificial salted soda, is particularly employed in the fabrication of marbled soaps, and besides its advautage of contracting t:ie paste of the soap, the sulphuret it contains contributes to develop the beauty and intensity of the marbling. TECHNICAL TREATISE OS SOAPS AND CANDLES. Previous Next
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