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Previous Next The best candle and soap tips online! per cent, of water. To bring it to a commercial state, it is calcined in a reverberatory furnace. This last operation destroys the coloring matter and drives off the excess of water with which it was combined. Pota3h thus prepared is very white; it is one of the best and richest found in commerce; it is advantageously employed in the fabrication of soft soaps, and according to several manufacturers, it is preferable to any other, because it gives more consistency to the soap. This effect is probably due to the presence of a certain quantity of soda. Composition of Commercial Potashes.—Carbonate of potash is the base of the commercial potashes, but besides this salt, they contain several others, and principally more or less considerable proportions of sulphate of potash and chloride of potassium. The presence of these salts is demonstrated by dissolving half an ounce of potash in 3J ounces of distilled water; the solution ia saturated by acetic or pure nitric acid. After the saturation, filter and divide the filtrate in two portions, which are separately submitted to the following reagents:—? 1. If, into one part of the liquor, chloride of larium is poured, an abundant white preeepitate, insoluble in nitric acid, is formed. Thia precipitate is sulphate of baryta, which indicates that the carbonate of potash contains a sulphate. 2, If, into the other part of the liquor, we pour a solution of nitrate of silver, a white precipitate, insoluble in.nitric acid, soluble in ammonia, is formed. This precipitate is chloride of silver, and indicates that the potash contains a chloride. The Bame methods may be employed to detect sulphates and chlorides in crude sodas. The most esteemed potashes are those of America, Russia, Tuscany, Dantziek, and particularly that made in France from beet molasses. The following table gives the composition of the principal commercial potashes. The free potash and soda are represented by their equivalent in pure carbonate. 40 TECHNICAL TREATISE OS SOAP AND "CANDLES. MATERIALS USED IN THE MANUFACTURE OF SOAPS. 41 Potnsli Potash cf Potash of Po tii» h Potash of America America or the or TuB.'any. Kussii. (red). (pearl ash) VuBjjea. molasses. Potassium sulphate . 13.47 14.11 15.32 14.38 38.84 1.197 Potassium chloride . 0-95 2.09 8.15 3.04 9.16 4.160 Potassium carbonate. 74.10 69.61 68.04 71.38 88.63 76.440 3odium carbonate. 3.00 3.09 5.85 2.31 4.17 16.330 Hygrometric water . 7.28 8.83 4.56 5.34 0.624 Insoluble substances) and loa& . . . i 1.20 3.28 2.64 3.73 3.86 1.249 100.00 100.00 100.00 100.00 100.00 100.000 Alkftlimetric degreeB 5<.O 53.1 55.0 54.4 31.6 69,3 We see, by the above table, that independently of the sulphates and chlorides, all potashes contain soda in variable proportion?; the American potash is that which contains the least, and that cf molasses contains the most. The insoluble residuum is partly composed of carbonates and phosphates of lime and magnesia, silicate of alumina, and the oxides of manganese and iron. The first of these oxides: colors them blue, the second communicates to them a red shade. Purification of Potash.—It is easy to separate from potash the greater part of the sulphate it contains. It is sufficient to dissolve it in the least possible quantity of water. The sulphate, much leas soluble than the carbonate, remains un-diesolved; it is stirred several times with water, which dissolves the alkali. This solution is used to dissolve a new quantity of potash. The sulphate washed and dried is sold for about half the price of the potash itself, and as that sulphate has co useful effect when mixed with potash, it is better to extract it and sell it separately. The chloride of potassium, very slightly soluble in a liquid saturated with carbonate of potash, is partly separated by the same process. The solutions obtained at 45°, by this process, are evaporated in kettles of gradually decreasing depth. It ia into the deepest kettle, directly heated, that the liquid is introduced; as fast as the evaporation reduces the volume, fill the kettle with the solution, and the other kettles with the solutions already concentrated in each-preceding kettle. In this way, as fast as the solution concentrates and retains the water with more tenacity, it is, placed in a flatter vessel, in which the stirring is more easily effected, and the column of liquid being of less height above the bottom, the saline incrustations, which, would be an, obstacle to tlie passage of heat, do not form so easily. The* desiccation is achieved in the latter kettle, which is natter. The carbonate of potash, economically purified by this' process, is used in the arts requiring a purer product than, commercial potash. Wherever wood-ashes can be bought at reasonable prices for the manufacture of soft Boaps, a large, Baving is attained and they deserve far more consideration than has hitherto been given them. Under favorable conditions the lye produced from wood-ashes will cost but one-lialf, often but one-third of the price of that made of potash. The reason for this is partly found in this, that by the home manufacture of potash in the form of lye, both the cost of boiling and calcination as well aa the expense of transportation, will be saved. The supply from this source is constantly diminishing, and recently commerce has been supplied from new sources. The rock-salt mines and the beet-engar factories have become the most reliable. Their potashes are richer in alkali ami freer from impurities, and are from this fact more desirable, requiring mush less labor in the preparation of the lyes. ' For the proper tests for potash the reader must turn to A Ikalimetry. SODA. JSoude, IV. Natron, Ger. Soda, the base of all hard soaps, exists in nature in the waters of various lakes and springs in many parts of the world, and the ashes of marine plants, whish were formerly the source of all commercial Boda. But since the discovery and manufacture of artificial soda from culinary salt, that is in general use for making soaps, and being furnished comparatively pure, and in a caustic and coocentrated form, 42 TECHNICAL TB.EATISE OK SOAP AND CANDLES. there is a saving of much labor and cost for plant outlay. The caustic sodas of commerce are generally sufficiently pure for all ordinary soaps of commerce, though for superior toilet soaps the lye should be perfectly pure. The soap maker will find it necessary to make hia own lye, and that from the crystallized carbonate of soda made caustic with the hydrate of lime is the most reliable. Chemically pure soda is composed of sodium and oxygen, but is never found in this state in nature; it is always in combination either with chlorine, with which it forms chloride of sodium (conunon salt), or with acids, principally carbonic acid. With this latter it forms the carbonate of eoda. This salt is met with abundantly in several countries of the world, and particularly in the East, where it has been known for a long time by the name of natron. Natural sodas are the carbonates of soda, obtained by the incineration of several species of plants growing on the seashore. These plants furnish very variable proportions of carbonate of soda mixed with different salts. Those which give the most are: the Salsola soda, and the Salicornia JSuropaca. During their vegetation, the plants draw from the soil the salt it contains, and assimilate the soda, which they transform, at least partially, into organic salts, principally in acetates and oxalate3, decomposable by heat. Gay-Lussac ascertained by analysis, that the salsola soda contained a considerable proportion of oxalate of soda. "When these plants are burned, tlte organic acids are destroyed, and the carbonic acid resulting from the combustion combines with the soda to form a carbonate. Sodas take their names from the countries which produce them. Soda of Farbonne.—This 8:>da, more generally known by the name of $alicoi\ is the best manufactured in France. It is the richest in pure or carbonated soda, which is the only useful alkali for the preparation of solid soaps. The plant which produces it is designated by the name of salicorna annua. The plant is cultivated in several parts of the south of France. The plant ia cut before its complete maturity; MATERIALS USED IN THE MANUFACTURE OP SOAPS. 43 is spread in the sun to dry, and then incinerated. Good salicors give from 20 to 25 per cent, of carbonate of soda. Soda of Aigues-Mortes.—This soda is prepared in the neighborhood of Aigues-Moites. It is obtained by the incineration of very different plants growing naturally and without cultivation, on the snores of the Mediterranean. These plants are collected, dried, and burned on the ground, or in proper furnaces. This soda is found as a black and uompact half-melted mass. It contains a large proportion of common salt. Its richness in carbonate of soda is about 8 to 10 per cent. Soda from. Sea-weeds.—This soda, prepared for a very long time on the coasts of Normandy and Brittany, varies greatly in its composition. It is furnished either by seaweeds, or by plants designated by botanists under the names of fucus maritimus, vesicidos habms, and commonly called goemon. These plants are collected at low tide, dried in the sun, and calcined. The residuum is a Mack mass, often porous, and is called kelp-soda. This soda is not very rich in carbonate, for its proportion is never -above 5 per cent.; it generally contains only from 2 to 3. It is most valuable on account of the bromine and iodine it contains. Spanish. Sodas.—Prior to the present century, Spain furnished, under the names of sodas of Alicante, Malaga, and Carthagena, the greater part of the carbonate of soda used in Europe. Among the numerous varieties of Spanish sodas, three kinds are principally distinguished in the market; they are known by the names of barilla, mixed, and salted barilla. The first, which is the richest in pure alkali, and consequently the most valuable, is furnished by the plant known by the name of salsola soda. "Wfcen the plant has attained its full growth, it is cut and dried in the sun, and incinerated in cylindrical pits dug in the ground, about five feet deep. To begin the operation, a few armfuls of dry material are thrown into the pit, and ignited. The combustion is kept up by adding little by little new dry plants and is 45 4.4: TECHNICAL TREATISE OH SOAP AND CANDLES. accelerated by stirring the mass from time to time with an iron rod. This operation lasts about four days, and is finished when the pit is filled to two-thirds or three-fourths of its depth with the products of the combustion. A few days after, the residuum is taken out, then broken into large pieces and put into barrels. The soda thus obtained is called soft barilla ; it is a bard and compact mass, of a gray-a3h color. .Recently prepared, its fracture is smooth. Mixed Barilla.—Mixed barilla is obtained in the same manner as tlie above, by the combustion of certain marine plants growing on the shores of the Mediterranean. The only difference between these two kinds is that the first is manufactured only from choice plants, carefully cultivated and free from weeds ; on the contrary, the mixed barilla is prepared with plants not so well cultivated, which grow in grounds nearer the sea—it is used to manufacture solid soaps. Salted Barilla.—This kind differs from the two above named by the strong proportion of neutral salts it contains, and by being less alkaline. The plants which produce it grow without cultivation on the sea-shore in soils strongly impregnated with salt. During their growth, these plants absorb a large quantity of salt, which is found in the ashes after the incineration. Although less pure, less alkaline, and less esteemed than the two last described, the salted barilla is still of great use in tlie manufacture of Marseilles soap. Ita blackish color, and its being more highly sulphuretted than the others, together with the large proportion of salt it contains, cause it to play, in the fabrication of marbled soap, the same part as salted soda. The blue of the marbling is brighter and more intense, it progressively contracts the molecules of the soap, and during the operation keeps it constantly separated from the lyes. But since the discovery of artificial soda its use is limited. Natron.—Is a natural sesqui-carbonate of soda, abundantly found in several parts of the world, and particularly in Egypt. Egyptian natron ia now extracted from two lakes, one MATERIALS USED IN THE MANUFACTURE OF SOAPS. near Cairo, and the other a short distance from Alexandria, During winter these lakes are filled with a water of a violet-red color, which passes by infiltration through the soil of the surrounding hills. During its course it runs through a soil in which salt and carbonate of lime are abundant. By the contact of the water, a spontaneous reaction takes place between these two salts, which are reciprocally decomposed; peliquesceut chloride of calcium ;s formed, which infiltrates into the lower part of the soil, and the sssqui-carbonate of soda, effloresces at the surface. This double decomposition is considerably favored by the dampness of the soil and the heat of the climate, ftain water or waters which exude from the soil dissolve the efflorescence.of carbonate of soda, and flow into the lakes in which they reach a height of about six feet. These lakes are from thirteen ami a half to fifteen miles in length, and about three-quarters of a mile in width. The bottom is stony and solid. During the great heat of the summer, these waters concentrate and evaporate, and the natron deposits on the soil, from which it is extracted in gray crystalline plates, which are purified and bleached by successive solutions and crystallizations. Commercial natron is in mass or in plates, with a grayish-white color. Its fracture is granular or crystalline, and it contains from 20 to 30 per cent, of pure SDda. In very dry years these lakes furnish about 450,000 lbs. of natron. In Hungary, and certain parts of South America, there are similar lakes furnishing, during the summer, an abundant efflorescence of sesqui-carbonate of soda. Natron is also collected in some of the lakes around Tripoli,but it is not so abundant aa in the lakes of Egypt, although the product is purer. History of the Fabrication of Artificial Soda.—The discovery of the process tor the manufkcture of soda from chloride of eodium has exercised on the progress of modern industry sq powerful an influence, that it is necessary here to dwell upon the circumstances under which it was produced. The pri-ority of this discovery has never been successfully contested, and the name of Leblanc, to whom it is due, is now known 46 TECHNICAL TREATISE OS SOAP AND CANDLES. all over the world; however, on many points of detail, some doubts existed, which liave only recently been explained. In 1856, M. Durcas presented to the Acadimie des Sciences, a paper which definitely established the true history of this important question. Long since, the old Academy of Sciences had offered a prize of 2400 francs ($480) for the conversion of chloride of sodium into carbonate of soda. Father Malherbe, in 1777, was the first who thought thai he had attained the industrial solution of the problem ; he proposed to convert first the salt into sulphate of soda, and then to heat this salt with charcoal and iron. Macquer and Montigny, in 1778, made a favorable report on this work. Guyton de Morveau, associated with Carny, had, a few years before, erected an establishment at Croisie, in which the salt, being mixed with lime, was afterwards allowed to rest in contact with the air. Very soon the carbonate of soda effloresced on the surface of the mixture, but the results were not economical. In 1789, De La Metherie proposed to calcine sulphate of soda with charcoal; he thought that he should thus obtain sulphurous acid and carbonate of soda, while in reality he obtained only eulphuret of sodium. This incorrect hypothesis, as we shall see, became the basis of the discovery of Leblanc. As early as 1787, he bad begun the study of this interesting question ; when he knew of the experiments recommended by De La Metherie, he tried them, and ascertaining their worthlessness, attempted to modify them. He then conceived the idea of associating the carbonate of lime with the sulphate of soda and charcoal, when its success was certain and the magnificent discovery of the fabrication of soda was accomplished. Ten months after the publication of De La Metherie, tlie problem was solved by Leblanc. It was then, that, associated with the Duke of Orleans, Dizd and Sliee, he thought of rendering his discovery an industrial one. In the act of association, and in a sealed package opened in 1855, he described the process as he then understood it. It consisted in heatiusr iu closed crucibles 100 parts of sulphate of soda, 50 of chalk, and 25 of charcoal. It MATERIALS USED IN THE MANUFACTURE OF SOAFS. 47 was not yet the industrial process as we know it at the present day. However, the trials in the laboratory were continued ; a manufactory was established at St. Denis, and soon (September 23,1791), on the report of D'Arcet, Desmarets, and de Servieres, Xieblanc obtained a patent for fifteen years. In his description, the crucibles had disappeared; they were superseded by a reverberatory furnace; ths proportion of sulphate of soda was diminished one-half; iu a word, the real industrial process was exposed with such precision that since that time very few changes have been made. Unhappily, fortune was not to reward Leblanc. The manufactory of St. Denis was just beginning to work when ttie revolution put an end to all business; the property of the Duke of Orleans was seized, and, the manufactory being included, the fabrication was stopped. Soon, the Continental war preventing the importation of Spanish sodas, the French industry felt the loss of this important element so essential to its work. Then, on the proposition of Carny, the committee of public safety obliged the inventors of the process to manufacture soda from chloride of Bodiurn, and to sacrifice to the country the fruit of their discoveries. Leblanc first offered his processes to the committee; soon a report from Lelievre, Felletier, D'Arcet, and Giroux, rendered them public, but it was not Leblanc who put them into practice. The property of the Duke of Orleans was sold, and the manufactory with them. However, that same nianufactory was given back to Leblanc as an indemnity for the publication of his process; but he could not find the capital necessary for conducting it, and, notwithstanding all his exertions, he utterly failed to accomplish anything, and was at the time of his death, in 1806, in a state of abject poverty. However, if the author of this discovery was dead, it was not so with the discovery itself; notwithstanding the difficulty of obtaining saltpetre to manufacture sulphuric acid, and then the sulphate of soda, the process of Leblanc was soon put in practice by several manufacturers. It was first Pityen, then Carny, who applied it: the first near Paris, the 48 Previous Next
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