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C3H6(C16H3102)
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See also:C3H6(C16H3102) 3+3NaOH =3NaC16H3102+C,Hs(OH)3 Palmitin. See also:Caustic Soda. See also:Soap. See also:Glycerin. Of the natural fats or glycerides contained in See also:oils the most important in addition to palmitin are stearin and olein, and these it may be sufficient to regard as the See also:principal fatty bodies concerned in soap-making. The See also:general characters of a soap are a certain greasiness to the See also:touch, ready solubility in See also:water, with formation of viscid solutions which on agitation yield a tenacious froth or " lather," an indisposition to crystallize, readiness to amalgamate with small proportions of hot water into homogeneous slimes, which on cooling set into jellies or more or less consistent pastes. Soaps give an alkaline reaction and have a decided acrid See also:taste; in a pure condition—a See also:state never reached in practice—they have neither See also:smell nor See also:colour. Almost without exception potash soaps, even if made from the solid fatty acids, are " soft," and soda soaps, although made with fluid olein, are " hard "; but there are considerable See also:variations according to the prevailing fatty See also:acid in the See also:compound. Almost all soda soaps are precipitated from their watery solutions by the addition of a sufficiency of See also:common See also:salt. Potash soap with the same reagent undergoes See also:double decomposition—a proportion being Changed into a soda soap with the formation of See also:potassium chloride. See also:Ammonia soaps have also been made, but with little commercial success; in 1906 H. See also:Jackson patented the preparation of ammonium oleate directly in the washing water, and it is claimed that for cleansing articles it is only necessary to immerse them in the water containing the preparation and then rinse. Soap when dissolved in a large amount of water suffers See also:hydrolysis, with formation of a precipitate of acid salt and a See also:solution containing See also:free See also:alkali. The reaction, however, is very complicated. See also:Chevreul found that a neutral salt soap hydrolysed to an acid salt, free alkali, and a small amount of fatty acid. Rotondi in 1885, however, regarded a neutral soap as hydrolysing to a basic salt, soluble in both hot and See also:cold water, and an acid salt, insoluble in cold and sparingly soluble in hot. Chevreul's views were confirmed in 1894 by See also:Krafft and Stern. The extent to which a soap is hydrolysed depends upon the acid and on the concentration of the solution; it is also affected by the presence of metallic salts, e.g. of See also:calcium and See also:magnesium. As to the detergent See also:action of a soap, See also:Berzelius held that it was due to the free alkali liberated with water; but it is difficult to see why a solution which has just thrown off most of its fatty acids should be disposed to take up even a glyceride, and, moreover, on this theory, weak cold solutions, in which the hydrolysis is consider-able, should be the best cleansers, whilst experience points to the use of hot concentrated solutions. It is more likely that the cleansing See also:power of soap is due to the inherent See also:property of its solution to emulsionize fats. This view is supported by Hillyer (Jour. Amer. Chem. See also:Soc., 1903, p. 524), who concluded that the cleansing power depended upon several factors, viz. the emulsionizing power, theproperty of penetrating oily fabrics, and lubricating impurities so that they can be readily washed away. See also:Resin soaps are compounds of soda or potash with the complex acids (chiefly abietic) of which coniferous resins consist. Their formation is not due to a true See also:process of saponification; but they occupy an important See also:place in compound soaps. Manufacture.—Numerous varieties of soaps are made; the purposes to which they are applied are varied; the materials employed embrace a considerable range of oils, fats and other bodies; and the processes adopted undergo many modifications. As regards processes of manufacture soaps may be made by the See also:direct See also:combination of fatty acids, separated from oils, with alkaline solutions. In the manufacture of stearin for candles, &c., the fatty See also:matter is decomposed, and the liquid olein, separated from the solid fatty acids, is employed as an ingredient in soap-making. A soap so made is not the result of saponification but of a See also:simple combination, as is the See also:case also with resin soaps. All other soaps result from the combination of fatty oils and See also:fat with potash or soda solutions under conditions which favour saponification. The soap solution which results from the combination forms soap-See also:size and is a mixture of soap with water, the excess alkali, and the glycerin liberated from the oil. In such See also:condition See also:ordinary soft soaps and certain kinds of hard soap are brought to the See also:market. In curd soaps, however, which See also:form the basis of most See also:household soap, the uncombined alkali and the glycerin are separated by " salting out, " and the soap in this condition contains about 3o% of water. Soap may be framed and finished in this state, but almost invariably it receives a further treatment called " refining " or " fitting," in which by remelting with water, with or without the subsequent addition of other agents to harden the finished product, the soap may be made to contain from 6o to 7o% of water and kept See also:present a See also:firm hard texture. Almost any fatty substance can be employed in soap-making; but the choice is naturally restricted by the See also:price of the fat and also the quality of the soap desired. The most important of the See also:animal fats are those of the ox and hog, and of the See also:vegetable oils See also:cotton-See also:seed and coco-See also:nut ; it is also to be remembered that resin, although not a fat, is also important in soap-making. Ox and See also:sheep See also:tallow, with the addition of resin, are the See also:primary materials for making the hard yellow or See also:primrose soaps; these tallows are often adulterated. The cheaper mottled and See also: The cold process, which is Dnly applicable to the manufacture of soaps from readily saponifiable oils, such as those of the coco-nut oil See also:group and also from castor oil, is but little used. In it the oils at 35° C. are stirred with concentrated alkali in an See also:iron or wooden tub, whereupon saponification ensues with a development of some See also:heat; the mixture being well agitated. After a few See also:hours the mixture becomes solid, and finally transparent; at this point the perfume is added, and the product framed and crutched (see under Marine Soap). By blending the coco-nut oil with other less saponifiable substances such as tallow, lard, cotton-seed oil, &c., and effecting the mixing and saponification at a slightly higher temperature, soaps are obtained which resemble milled toilet soaps. Soaps made by this process contain the glycerin originally present in the oil, but, in view 298 of their liability to contain free alkali and unsaponified oil, the See also:appearance was formerly highly valued as an indication of freedom process has been largely given up. The process of soap-boiling is carried out in large iron boilers called " soap pans " or " coppers," some of which have capacity for a See also:charge of 3o tons or more. The See also:pan proper is surmounted by a See also:great See also:cone or hopper called a curb, to provide for the foaming up of the boiling See also:mass and to prevent loss-from overflowing. Formerly the pans were heated by open firing from below; but now the almost universal practice is to See also:boil by steam injected from perforated pipes coiled within the pan, such injection favouring the See also:uniform See also:heating of the mass and causing an agitation favourable to the ultimate mixture and saponification of the materials. Direct firing is used for the second boiling of the soap mixture; but for this superheated steam may with See also:advantage be substituted, either applied by a steam jacket See also:round the pan or by a closed coil of See also:pipe within it. In large pans a See also:mechanical stirring apparatus is provided, which in some cases, as in Morfit's steam " twirl," is formed of the steam-heating tubes geared to rotate. Autoclaves, in which the materials are boiled under pressure, are also employed for certain soaps. The process of manufacturing soaps by boiling fatty acids with caustic alkalis or See also:sodium carbonate came into practice with the development of the manufacture of candles by saponifying fats, for it provided a means whereby the oleic acid, which is valueless for See also:candle making, could be worked up. The combination is effected in open vats heated by a steam coil and provided with a stirring appliance; if soda ash be used it is necessary to guard against boiling over. (See under Curd Soap.) Curd Soap.—This variety is manufactured by boiling the fat with alkali and removing the unused lye, which is afterwards worked up for glycerin. The oil mixture used differs in the several manufacturing countries, and the commercial name of the product is correspondingly varied. In See also:Germany tallow is the principal fat; in See also:France olive oil occupies the See also:chief place and the product is known as See also:Marseilles or See also:Castile soap; and in See also:England tallow and palm oil are largely used. But in all countries a mixture of several oils enters into the See also:composition of curd soaps and the proportions used have no fixity. For each ton of soap to be made from 12 to i6 cwt. of oil is required. The soap pan is charged with the tallow or other fat, and open steam is turned on. So soon as the tallow is melted a quantity of weak lye is added, and the agitation of the injected steam causes the fat and lye to become intimately mixed and produces a milky emulsion. As the lye becomes absorbed, a condition indicated by the taste of the goods, additional quantities of lye of increasing strength are added. After some See also:time the contents of the pan begin to clear and become in the end very transparent. Lye still continues to be poured in till a See also:sample tastes distinctly alkaline—a test which indicates that the whole of the fatty acids have been taken up by and combined with the alkali. Then without further addition of alkali the boiling is continued for a few minutes, when the soap is ready for salting out or " graining." Either common salt or strong brine in measured quantity is added to the charge, and, the soap being insoluble in such salt solution, a separation of constituents takes place: the soap collects on the See also:surface in an open granular condition, and the spent lye sinks to the bottom after it has been See also:left for a See also:short time. to See also:settle. Suppose that a pure soap without resin is to be made—a product little seen in the market—the spent lye is run off, steam is again turned on, pure water or very weak lye run in. and the contents boiled up till the whole is thin, See also:close and clear. The soap is from this again grained off or salted out, and the underlye so thrown down carries with it coloured impurities which may have been in the materials or which arise from contact with the boiler. Such washing process may have to be repeated several times when impure materials have been used. The spent lye of the washing being drained off, the soap is now " boiled for strength." Steam is turned on, and, the mass being brought to a clear condition with weak lye or water, strong lye is added and the boiling continued with close steam till the lye attains such a state of concentration that the soap is no longer soluble in it, and it will See also:separate from the caustic lye as from a common salt solution. The contents of the pan are once more allowed to cool and settle, and the soap as now formed constitutes a pure curd coap, carrying with it some See also:pro-portion of uncombined alkali, but containing the minimum amount of water. It may be skimmed off the underlye and placed direct in the frames for solidification; but that is a practice scarcely at all followed, the addition of resin soap in the pan and the subsequent " crutching in " of silicate of soda and adulterant mixings being features common to the manufacture. The lye from the strengthening boil contains much alkali and is used in connexion with other boilings. Mottled Soap.—A curd soap prepared from kitchen fat or bone grease always carries with it into the cooling See also:frame a considerable amount of coloured impurity, such as iron sulphate, &c. When it is permitted to cool rapidly the colouring matter remains uniformly disseminated throughout the mass; but when means are taken to cause the soap to cool and solidify slowly a segregation takes place: the stearate and palmitate form a semi-crystalline solid, while the oleate, solidifying more slowly, comes by itself into translucent See also:veins, in which the greater See also:part of the coloured matter is See also:drawn. In this way curd, mottled or marbled soap is formed, and such mottled from excess of water or other See also:adulteration, because in fitted soaps the impurities are either washed out or fall to the bottom of the mass in cooling. Now, however, the mottled soaps, See also:blue and grey, are produced by working colouring matter, See also:ultramarine for blue, and See also:manganese dioxide for grey, into the soap in the frame, and mottling is very far from being a certificate of excellence of quality. Yellow Soap consists of a mixture of any hard fatty soap with a variable proportion--up to 4o% or more—of resin soap. That sub-stance by itself has a tenacious gluey consistence, and its inter-mixture in excess renders the resulting compound soft and greasy. The ordinary method of adding resin consists in stirring it in small fragments into the fatty soap in the See also:stage of clear-boiling; but a better result is obtained by separately preparing a fatty soap and the resin soap, and combining the two in the pan after the underlye has been salted out and removed from the fatty soap. The compound then receives its strengthening boil, after which it is fitted by boiling with added water or weak lye, continuing the boil till by examination of a sample the proper consistency has been reached. On settling the product forms three layers: the uppermost is a thin crust of soap which is worked up again in the pan; the second is the desired soap; next there is a dark-coloured weak soap termed nigre, which, because it contains some soap and alkali is saved for future use; underneath these is a solution of alkaline salts with a little free alkali. Treatment of Settled Soap.—The upper layer having been removed, the desired soap is ladled out or ran off to a crutcher, which is an iron pan provided with See also:hand or mechanical stirring appliances. It is here stirred till it becomes See also:ropy, and the perfume, colour or any other substance desired in the soap is added. The soap is now ready for framing The frames into which hard soaps are ladled for cooling and solidification consist of rectangular boxes made of iron plates and See also:bound and clamped together in a way that allows the sides to be removed when required; wooden frames are used in the case of mottled soaps. The solidification is a very See also:gradual process, depending, of course, for its completion on the size of the See also:block; but before cutting into bars it is essential that the whole should be set and hardened through and through, else the See also:cat bars would not hold together. Many ingenious devices for forming bars have been produced ; but generally a strong frame is used, across which See also:steel wires are stretched at distances equal to the size of the bars to be made, the blocks being first cut into slabs and then into bars. Marine Soap.—These soaps are so named because they are not insoluble in a strong solution of salt; hence they form a lather and can be used for washing with See also:sea-water. Being thus soluble in salt water it cannot, of course, be salted out like common soaps; but if a very concentrated salt solution is used precipitation is effected, and a curd soap is separated so hard and refractory as to be practically useless. Coco-nut soap (see above) is typical of this class. Its property of absorbing large proportions of water, up to 8o %, and yet present the appearance of a hard solid See also:body, makes the material a basis for the hydrated soaps, smooth and marbled, in which water, sulphate of soda, and other alkaline solutions, soluble silicates, fuller's See also:earth, See also:starch, &c. See also:play an important and bulky part. Coco-nut soap also forms a principal ingredient in compound soaps meant to imitate curd and yellow soaps. Two principal methods of preparingsuch compound soaps are employed. In the first way the ordinary oil and the coco nut oil are mixed and saponified together as de-scribed above. According to the second See also:plan, the ordinary oil is treated as for the preparation of a curd soap, and to this the coconut soap separately saponified is added in the pan and both are boiled together till they form a homogeneous soap. Silicate Soaps.—A further means of enabling a soap to contain large proportions of water and yet present a firm consistence is found in the use of silicate of soda. The silicate in the form of a concentrated solution is crutched or stirred into the soap in a mechanical mixing See also:machine after the completion of the saponification, and it appears to enter into a distinct chemical combination with the soap. While silicate soaps See also:bear heavy watering, the soluble silicate itself is a powerful detergent, and it possesses certain advantages when used with hard See also:waters. Soft Soap.—Soft soaps are made with potash lyes, although in practice a small quantity of soda is also used to give the soap some consistence. There is no separation of underlyes in potash soap, consequently the product contains the whole constituents of the oils used, as the operation of salting out is quite impracticable owing to the double decomposition which results from the action of salt, producing thereby a hard, principally soda soap- with formation of potassium chloride. Owing to this circumstance it is impossible to potassium See also:fit " or in any way purify soft soap, and all impurities which go into the pan of. See also:necessity enter into the finished product. The making of soft soap, although thus a much less complex process than hard soap making, is one that demands much skill and experience for its success. From the conditions of the manufacture care must be taken to regulate the amount and strength of the alkali in proportion to the oil used, and the degree of concentration to which the boiling ought to be continued has to be determined with close observation. Toilet Soaps, &c.—Soaps used in See also:personal See also:ablution in no way differ from the soaps previously alluded to, and may consist of any of the varieties. It is of consequence that they should, as far as possible, be free from excess of alkali and all other salts and See also:foreign ingredients which may have an injurious effect on the skin. The manufacturer of toilet soap generally takes care to present his wares in convenient form and of agreeable appearance and smell; the more weighty See also:duty of having them free from uncombined alkali is in many cases entirely overlooked. Transparent soaps are prepared by dissolving ordinary soap in strong See also:alcohol and distilling off the greater portion of the alcohol till the See also:residue comes to the condition of a thick transparent jelly. This, when See also:cast into forms and allowed to harden and dry slowly, comes out as transparent soap. A class of transparent soap may also be made by the cold process, with the use of coco-nut oil, castor oil and See also:sugar. It generally contains a large amount of uncombined alkali, and that, with its unpleasant odour of coco-nut oil, makes it a most undesirable soap for personal use. Toilet soaps of common quality are perfumed by simple melting and stirring into the mass some cheap odorous body that is not affected by alkalis under the See also:influence of heat. The finer soaps are perfumed by the cold method; the soap is shaved down to thin slices, and the essential oil kneaded into and mixed with it by See also:special machinery, after which it is formed into cakes by pressure in suitable moulds. The greater quantity of high-class toilet soaps are now made by a milling process. A high class soap, which after framing contains about 30 %b of water, is brought down to a water content of II-14 % by drying in See also:chambers through which warm See also:air is circulated. The soap is now milled in the form of See also:ribbons with the perfume and colouring matter, and the resulting strips are welded into bars by forcing through a heated nozzle. The bars are then cut or moulded into tablets, according to the practice of the manufacturer. Glycerin soap ordinarily consists of about equal parts of pure hard soap and glycerin (the latter valuable for its emollient properties). The soap is melted by heat, the glycerin is stirred in, and the mixture strained and poured into forms, in which it hardens but slowly into a transparent mass. With excess of glycerin a fluid soap is formed, soap being soluble in that body, and such fluid soap has only feeble lathering properties. Soap containing small proportions of glycerin, on the other hand, forms a very tenacious lather, and when soap bubbles of an enduring See also:character are desired glycerin is added to the solution. Soaps are also prepared in which large proportions of See also:fine See also:sharp See also:sand, or of powdered See also:pumice, are incorporated, and these substances, by their abrading action, powerfully assist the detergent influence of the soap on hands much begrimed by manufacturing operations.' Medicated soaps, first investigated scientifically by liana of See also:Hamburg in 1886, contain certain substances which exercise a specific influence on the skin. A few medicated soaps are prepared for See also:internal use, among which are croton soap and See also:jalap soap, both gentler cathartics than the uncompounded medicinal principles. Medicated soaps for See also:external use are only employed in cases of skin ailments, as prophylactic washes and as disinfectant soaps. Among the principal varieties are those which contain carbolic acid and other ingredients of See also:coal See also:tar, salicylic acid, See also:petroleum, See also:borax, camphor, See also:iodine, See also:mercurial salts, See also:sulphur and See also:tannin. Arsenical soap is very much employed by taxidermists for the preservation of the skins of birds and mammals. See also:Miscellaneous Soaps.—The so-called " floating soaps " are soaps made lighter than water either by inserting See also:cork or a metallic See also:plate so as to form an air space within the tablet. The more usual method is to take milling soap, neutralize it with sodium bicarbonate or a mixture of fatty acids, and, after perfuming, it is aerated by mixing the hot soap with air in a specially designed crutcher. Shaving soaps, which must obviously be free from alkali or any substance which irritates the skin, are characterized by readily forming a permanent lather. This property is usually obtained by mixing soft and hard soaps, or, more rarely, by adding See also:gum tragacanth to a hard soap. In the textile trades the See also:wool scourer employs a neutral olive-oil soap, or, on See also:account of its cheapness, a neutral curd or curd mottled See also:brand ; the cotton cleanser, on the other hand, uses an alkaline soap, but for cleaning printed cottons a neutral olive-oil curd soap is used, for, in this case, free alkali and resin are objectionable; olive-oil soap, free from caustic alkali, but often with sodium carbonate, is also used in cleansing silk See also:fibres, although hard soaps free from resin are frequently employed for their cheapness. Soaps of smaller moment are the See also:pearl ash soaps used for removing tarry stains; ox-See also:gall soaps for cleaning carpets; See also:magnesia, See also:rouge and See also:chalk soaps for cleaning plate, &c. Soap See also:Analysis.—The most important points in soap analysis are (I) determination of the fatty matter, (2) of the See also:total alkali, (3) of the substances insoluble in water, (4) of the water. The first is carried out by saponifying the soap with acid in the heat when the fatty acids come to the surface. If it fails to form a hard cake on cooling, a known See also:weight of See also:wax may be added and the product re-heated. The cake on weighing gives the free acid. The total alkali is determined by incinerating a weighed sample in a See also:platinum dish, dissolving the residue in water, filtering and titrating the filtrate with See also:standard acid. The residue on the See also:filter See also:paper gives (3) the sub-stances insoluble in water. The water in a soap is rarely directly determined; when it is, the soap, in the form of shavings, is heated to 105° C. until the weight is See also:constant, the loss giving the amount of ' " Soap powders " and " soap extracts " are powdered mixtures of soaps, soda ash or ordinary sodium carbonate.water, With genuine soaps, however, it suffices to calculate the fatty acids as anhydrides and add to this the amount of alkalis, and estimate the water by difference. The See also:complete analysis involves an examination of the fatty matter, of the various forms in which the alkalis are present—free and combined glycerin, &c.
See also:Commerce.—Marseilles has See also:long been recognized as the most important centre of the soap See also:trade, a position that See also:city originally achieved through its ready command of the supplies of olive The city is still very favourably situated for obtaining supplies of oils both See also:local and foreign, including See also:sesame, ground nut, castor oil, &c. In England, during the reign of See also: See L. L. Lamborn, See also:Modern Soaps, Candles and Glycerin (1906); W. H. See also:Simmons and H. A. See also:Appleton, The Handbook of Soap Manufacture (1908); also J. Lewkowitsch, Oils, Fats and Waxes. SOAP-BARK, the inner bark of Quillaja saponaria, a large See also:tree which grows in See also:Chile. Reduced to See also:powder, it is employed as a substitute for soap, since it forms a lather with water, owing to the presence of a See also:glucoside saponin, sometimes distinguished as Quillai saponin. The same, or a closely similar substance, is found in soapwort (Saponaria ojcinalis), in See also:senega See also:root (Polygala senega) and in See also:sarsaparilla; it appears to be chemically related to 'digitonin, which occurs in See also:digitalis. The saponins (with few exceptions) have the general See also:formula (C0Hs,,_sO1o,-and by the action of dilute acids they are hydrolysed into sugars and sapogenins, which are usually inert pharmacologically. An alternative name for them, and especially for those which are pharmacologically active, is sapotoxins; on this nomenclature the hydrolytic products are termed saponins. Applied as a See also:snuff to the mucous membrane of the See also:nose, saponin (either in soap-bark or in senega root) promotes a violent See also:sneezing. Solutions injected under the skin are violent local irritants and general depressants. Additional information and CommentsThere are no comments yet for this article.
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