Soaps. U.S.D. 21st  1926
compiled and edited by Ivor Hughes.

SAPO. U. S. Br. SOAP [Olive Oil Castile Soap] " Soap prepared from olive oil and sodium hydroxide." U. S. " Hard Soap is soap made from sodium hydroxide and olive oil; it contains not more than 30 per cent, of water." Br. 

Sapo Duma, Br.; Hard Soap, Castile Soap; Sapo Amygdainus; Sapo Medicinalia, Fr. Cod.; Savon medicinal, Savon blanc, Fr.; Sapo medicatus, P. G.; Medizinische Seife, Oel-Sodaseife, Seife, Spanische Seife, G.; Sapone medicinale, S. amigdalino, Sapone duro, It.; Jabon de aceite de olivas, Jabon, Sp.

Soap is believed to have been discovered by the Gauls shortly after the beginning of the Christian Era. For a history of soap and of cleansing methods used by ancient races, see papers by Abraham (J. A. Ph. A., 1916, v, 205) and by Cook (A. J. P., 1925, xcvii, 398). Soaps embrace all those compounds which result from the reaction of salifiable bases with fats and oils. Fats and oils, as has been explained under the titles Adeps and Olea, consist generally of three glyceryl esters, two solid, differing in fusibility, called stearin and palmitin, and one liquid, called olein. Stearin is found most abundantly in fats which are firm and solid, as suet and tallow, and palmitin and olein in the oils. When the fats and oils undergo saponification by reaction with a salifiable base, these three esters are decomposed into the fatty acids called stearic, palmitic, and oleic acids, which unite with the base to form the soap, and into glycerin (glycerol), which is set free. Hence, it ,is obvious that soaps are mixed stearates, palmitates, and oleates of certain bases. Soaps are divided into the soluble and the insoluble. The soluble soaps are combinations of the fatty acids with sodium, potassium or ammonium hydroxides; the insoluble consist of the same acids united with other earths or metallic oxides. 

It is the soluble soaps only that are detergent, and to which the name soap is usually applied. Several of the insoluble soaps are employed in pharmacy, as, for example, the lead monoxide soap, or lead plaster, and the lime soap, or lime liniment. (See Emplastrum Plumbi Oleatis and Linimentum Calais.) The two official soaps are of the soluble kind. One is a soda soap, made with olive oil (Castile soap), the other a potassium soap (soft soap). (See Sapo Mollis.) The consistence of the fixed alkaline soaps depends partly on the nature of the oil or fat, and partly on the alkali present. Soaps are harder the more stearate and palmitate they contain, and softer when the oleate predominates, and, as regards the alkali present, they are harder when formed with sodium hydroxide, and softer when containing potassium hydroxide. Hence it is that of pure soaps, considered as salts, sodium stearate is the hardest and least soluble, and potassium oleate the softest and most soluble. Liquid soaps are largely coming into use as economical and sanitary substitutes for soap in public lavatories. Several good formulas have been proposed by E. R. Jones (J. A. Ph. A., 1914, 1537) for use with soft, medium and hard waters, respectively. 

The following is an outline of the process for making soap. The oil or fat is boiled with a solution of caustic alkali, beginning with a weak solution, and as saponification proceeds using a stronger lye until the whole forms a thick mass, which can be drawn out into long clear threads. After the soap is completely formed, the next step is to separate it from the excess of alkali, the glycerin, and the redundant water. This is effected by adding common salt, or a very strong alkaline lye, in either of which the soap is insoluble. The same end may be attained by boiling down the solution until the excess of the alkali forms a strong alkaline solution, which acts the same part in separating the soap as the addition of a similar solution. As soon as the soap is completely separated, it rises to the surface, and, when it has ceased to froth in boiling, it is ladled out into wooden frames to congeal, after which it is cut into bars by means of a wire. 

The soap, as first separated, is called grain soap. It may be purified by dissolving it in an alkaline lye and separating it by common salt. During this process the impurities subside, and the soap combines with more water, and hence it becomes weaker, although purer and whiter. If the grain soap be not purified, it will form marbled soap, the colored streaks arising principally from an insoluble soap of oxidized iron. Sometimes the marbled appearance is produced by adding to the soap, as soon as it is completely separated, a fresh portion of lye, and immediately afterwards a solution of ferrous sulphate. The greenish-black ferrous hydroxide is precipitated, and gives rise to dark-colored streaks, which, by exposure to the air, become red in consequence of the conversion of the black hydroxide into the ferric hydroxide. When commercial toilet soap is required, the grained soap, or, as it is sometimes called, boiled soap, is often remelted, perfumed, and worked over by the process of milling, plotting, and moulding, whereby the soap is brought into the desired shape for popular use. The cold process is also used, and is preferred by many because of its simplicity and economy. 

The following (from Sadtler's Industrial Organic Chemistry, 1906, 64) gives the outlines of the process. The so-called " cold process" requires the use of exact weights of well-refined fats and of caustic soda of a given specific gravity (from 32� to 36� B.), the quantities being such that only just enough soda is present to completely saponify the fat. The materials are allowed to stand together for a short time and then thoroughly mixed in a kettle provided with steam agitating paddles, and kept at a temperature of not over 48.9� C. The reaction proceeds rapidly, and after some fifteen minutes the materials have so far united that they will not separate on standing, although the complete saponification of the charge may require days. They are then run out into the cooling frames. It is obvious that soaps made in this way retain all the glycerin originally combined with the fatty acids disseminated through the particles of soap, and belong to the class of " filled " or " padded " soaps. 

When cocoanut oil alone is used, the temperature of working in this cold process need not be higher than 23.9� C. in summer and 32.2� C. in winter; if one-half tallow, from 40� to 42.2� C., and if two-thirds tallow, from 45� to 48.9� C. is necessary. A well-refined tallow can be saponified in this way, too, and rosin may be added. For a practical process for making soap in small quantities without boiling, see U. S. D., 19th edition, page 1089. The official soap (Sapo, TJ. S.; Sapo Durus, Br.) is an olive oil soda soap, made on the same general plan as that just explained.

Common soap is also a soda soap; but instead of olive oil it is made from various vegetable or animal fats. This soap corresponds with the white soap of northern European countries and of the United States. Besides the official soaps of the U. S. and Br. Pharmacopoeias, there are many other varieties, more or less used for medicinal or economical purposes. Starkey's soap is prepared by uniting, by trituration, equal parts of potassium carbonate, oil of turpentine, and Venice turpentine. Beef marrow soap is a fine animal oil soap, also included in the French standard.

 Windsor Soap is a scented soda soap, made of one part of olive oil and nine parts of tallow. Eau de luce (aqua Incite) is a kind of liquid soap, formed by mixing a tincture of oil of amber and balsam of Gilead with ammonia water. Transparent soap is prepared by several methods. In one process, glycerin is added which makes a clear transparent mass upon solidification; soap containing glycerin, however, is very hygroscopic. 

The German transparent soap always contains a large quantity of cocoanut-oil soap. Modern transparent soaps owe their transparency usually to their having been made into an alcoholic solution and then the alcohol carefully recovered, which leaves the mass transparent. Cheap grades of transparent soaps often owe this property to the presence of sugar which communicates the desired property when present to the extent of 5 or 10 per cent. Marine soaps, or hard water soaps, are soaps which possess the property of lathering freely with hard water.  They are usually manufactured from cocoanut oil. 

Palm soap is prepared from sodium hydroxide and palm oil, to which tallow is added to increase its firmness. If it be wanted white, the palm oil may be bleached by heat, potassium dichromate with sulphuric acid, chlorine, or exposure to the sun. This soap has a yellowish color, and the agreeable odor of violets derived from the oil. 

Soap balls are prepared by dissolving soap in a little water and then forming it with starch into a mass of the proper consistence. Common yellow soap (rosin soap) derives its character from an admixture of rosin with the fats, rosin being saponifiable and yielding a detergent soap. Sodium silicate is largely used as a filler which adds to the detergent properties of the soap. It is too harshly alkaline for use in toilet soaps or soaps intended for anything but the crudest purposes. 

Borax soap is soap containing borax as an added detergent ingredient. Cereals such as cornmeal, oatmeal, etc., are sometimes added to soap for special purposes. Their mechanical presence is sometimes of value, though they are frequently added for cheapening purposes. Soaps with fancy descriptive names are usually deceptive in their character. Lemon juice, buttermilk, seaweed, etc., are only of advertising value as soap constituents. 

Floating soaps are those in which minute air bubbles have been incorporated in the soap mass before cooling. This makes the cakes buoyant. All varieties of soap are now manufactured in the United States. Large amounts of olive oil soaps and very fine toilet soaps are, however, imported from France, Italy, and Spain. 

The following standards and specifications have been adopted by the U. S. Bureau of Standards for various types of soaps, and have been published in Circular No. 62 of the Department of Commerce, June, 1919. In these specifications matter volatile at 105� C. is considered as moisture although volatile oils, when present as perfumes, are driven off at this temperature. Milled Toilet Soap.�Matter volatile at 105� C., not over 15 per cent.; free alkali as sodium hydroxide, not over 0.1 per cent.; alkaline salts as sodium carbonate, not over 0.3 per cent.; sodium sulphate, not over 0.1 per cent.; sodium chloride, not over 0.3 per cent.; material insoluble in water, not over 0.1 per cent.; unsaponifiable matter, not over 0.1 per cent.; rosin, sugar, and other foreign matter must be absent. 

White Floating Soap has the same standards as milled toilet soap, except that the matter volatile at 105� C. may reach 34 per cent, and the alkaline salts 0.5 per cent. Liquid Soap must contain not less than 20 per cent, of anhydrous soap, not more than 0.3 per cent, of alkaline salts, not more than 0.3 per cent, of potassium chloride, and no sulphates nor sugar. Shaving Soap must meet the following requirements: Matter volatile at 105� C., not over 15 per cent.; free alkali, not over 0.3 per cent.; potassium chloride, not over 0.3 per cent.; matter insoluble in water, not over 0.1 per cent.; unsaponifiable matter, not over 0.1 per cent.; rosin, sugar and other foreign matters must be absent, and at least 50 per cent, of the total alkali must be potash. 

The following are the specifications for salt water soap, which is a cocoanut oil soap capable of lathering in brine: Matter volatile at 105" C., not over 55 per cent.; free alkali, not over 0.5 per cent.; alkaline salts, as sodium carbonate, not less than 2 per cent, nor more than 3 per cent.; chlorides, not less than 2.5 per cent, nor more than 3.5 per cent.; rosin, sugar, and other foreign matters must be absent. Special Grade 

Laundry Soap.�Matter volatile at 105� C., not over 34 per cent.; free alkali as sodium hydroxide, not over 0.2 per cent.; alkaline salts, not over 1 per cent.; sodium chloride and sulphate, not over 1 per cent.; matter insoluble in water, not over 0.1 per cent.; rosin, not over 15 per cent.

Ordinary Grade Laundry Soap.� Matter volatile at 105� C., not over 34 per cent.; free alkali as sodium hydroxide, not over 0.5 per cent.; alkaline salts, not less than 2 per cent, nor more than 6 per cent.; sodium chloride, not over 1 per cent.; sodium sulphate, not over 1 per cent.; matter insoluble in water, not over 0.5 per cent.; rosin, not over 25 per cent. 

Chip Soap.�Matter volatile at 105� C., not over 15 per cent.; free alkali as sodium hydroxide, not over 0.5 per cent.; alkaline salts, not over 0.5 per cent.; sodium chloride, not over 0.5 per cent.; matter insoluble in water, not over 0.1 per cent. 

Soap Powder.�Anhydrous soap, not less than 30 per cent, nor more than 35 per cent.; sodium carbonate, not less than 40 per cent. Hand Grit Soap.�Matter volatile at 105� C., not over 15 per cent.; free alkali as sodium hydroxide, not over 0.1 per cent.; alkaline salts, not over 0.3 per cent.; insoluble siliceous material, not less than 30 per cent, nor more than 35 per cent.; 98 per cent, of the siliceous material must pass through a sieve having 200 meshes to the linear inch; rosin, sugar, and other foreign matters must be absent. 

Scouring Soap A.�Matter volatile at 105� C., not over 5 per cent.; free alkali as sodium hydroxide, not over 0.1 per cent.; alkaline salts, not over 1 per cent.; insoluble siliceous material, not less than 88 per cent, nor more than 93 per cent.; all of the siliceous material must pass through a sieve having 100 meshes to the linear inch, and at least 95 per cent, must pass through a sieve having 200 meshes to the linear inch, and it must not scratch glass. Rosin, sugar, and other foreign matters must be absent. 

Scouring Soap B.�Matter volatile at 105� C., not over 5 per cent.; free alkali as sodium hydroxide, not over 0.1 per cent.; alkaline salts, not over 3 per cent.; insoluble siliceous material, not less than 75 per cent, nor more than 85 per cent. The insoluble siliceous material should mainly consist of quartz, and it must all pass through a sieve having 100 meshes to the linear inch, and at least 75 per cent, must pass through a sieve having 200 meshes to the linear inch. Rosin, sugar, and other foreign matters must be absent. 

Automobile Soap.�Matter volatile at 105� C., not over 55 per cent.; free alkali as sodium hydroxide, not over 0.05 per cent.; free oleic acid, not over 0.1 per cent.; matter insoluble in water, not over 0.1 per cent.; alkaline salts, not over 0.5 per cent. Properties.�Soap, whatever may be its variety, has the same general properties. Its aspect and consistence are familiar to every one. Its odor is peculiar, and its taste slightly alkaline. It is usually somewhat heavier than water, and therefore sinks in that liquid. Exposed to heat it quickly fuses, swells up, and is decomposed. It is soluble in water, and more readily in hot than in cold. Acids added to an aqueous solution of soap combine with the alkali, and set free the fatty acids, which, being diffused through the water give it a milky appearance. Its decomposition is also produced by metallic salts, which invariably give rise to insoluble soaps. Soap is soluble in cold and abundantly in boiling alcohol. This solution constitutes the tincture of soap. The efficacy of soap as a detergent depends probably in chief part on its power of emulsifying fats, although also in part upon its hydrolytic decomposition when in solution, whereby alkali is liberated which saponifies and emulsifies grease and fatty substances rendering them readily removable in the washing processes.

The chief adulterations in soap are lime, silica, gypsum, heavy spar, steatite, pipe-clay, and sodium sulphate. Some of these constituents, however, are normal ingredients of soaps intended for special purposes as for scouring. When adulterated with these substances, it will not be entirely soluble in alcohol. 

Description and Physical Properties. " A white or whitish solid, in the form of bars, hard, yet easily cut when fresh, or a fine, yellowish-white powder. It has a faint, characteristic odor, free from rancidity and a disagreeable, alkaline taste. Soap is soluble in water and in alcohol, more readily, however, with the aid of heat. An aqueous solution of Soap is alkaline to indicators. " Dissolve about 0.5 Gm. of Soap, accurately weighed, in 10 cc. of alcohol, evaporate the mixture to dryness in a tared beaker containing 1 Gm. of clean sand, which has been previously dried at 110� C., and dry the residue to constant weight at 110� C.: the loss does not exceed 36 per cent for unpowdered Soap or 10 per cent, for powdered Soap (water). A solution of a quantity of Soap corresponding to 0.64 Gm. of dried Soap in 25 cc. of hot alcohol does not gelatinize on cooling to 20� C. (soap from animal fats). Ten cc. of an aqueous solution of Soap (1 in 20) remains unchanged in color upon the addition of ammonium sulphide T.S., and upon acidulating another portion of 10 cc. of the solution with hydrochloric acid and filtering, the filtrate remains unchanged in color when an equal volume of hydrogen sulphide T.S. is added and the mixture allowed to stand well-stoppered, in a warm place, for half an hour (heavy metals). Dissolve about 10 Gm. of Soap, accurately weighed, in 100 cc. of neutralized alcohol, with the aid of heat. Transfer the undissolved residue, if any, to a tared filter which has been dried at 100� C., and wash it thoroughly with boiling neutralized alcohol. The weight of the residue after drying at 100� C. does not exceed 1 per cent, of the weight of dry Soap taken (sodium chloride, carbonate, silica, or other alcohol-insoluble substances). This residue, thoroughly washed with distilled water and dried at 100� C., does not yield a residue exceeding 0.15 per cent, of the weight of dry Soap taken (silica or other water-insoluble substances). The alcoholic filtrate and washings from the preceding test are not reddened by 3 drops of phenolphthalein T.S. (sodium hydroxide). Dissolve about 10 Gm. of Soap in 200 cc. of hot distilled water, add 2 drops of methyl orange T.S. and then diluted sulphuric acid with constant stirring until the aqueous layer becomes red. Boil the mixture until the supernatant layer of the fatty acids is clear and free from solid particles. 

Separate the aqueous layer with the aid of a siphon and wash the fatty acids by decantation with hot distilled water, until a 10 cc. portion of the washings, acidulated with a drop of hydrochloric acid, no longer gives a precipitate on the addition of barium chloride T.S. Place the dish containing the fatty acids on a water bath and heat until they are completely liquefied, filter the warm acids through a dry filter in a hot-water funnel into a flat dish, and dry over sulphuric acid. The iodine number of the acids thus obtained is not less than 84 and not more than 90. " Preserve in well-closed containers." U. S. " Greyish-white, yellowish-white, or greenish-white, becoming horny and pulverisable when dried. Nearly inodorous. Soluble in 20 parts of cold water, and in 1.5 parts of hot water; soluble in alcohol (90 per cent.), more readily when warmed. Responds to the tests for alkaline hydroxides and carbonates and for free fatty acids described under ' Sapo Animalis.' Does not impart a greasy stain to white unglazed paper (absence of free oil). Loses not more than 30 per cent, of its weight when dried at 110� C. Ash not deliquescent (absence of potassium soap). The absence of fatty acids derived from oils other than Olive Oil is determined by the following process:

Dissolve the Soap in hot water, add a slight excess of hydrochloric acid and heat on a water-bath until the liberated fatty acids form a transparent layer. Separate the fatty acids on a wet filter-paper, and wash with hot water until the washings are neutral to solution of methyl orange. Filter the oily layer through a dry filter-paper in a warm oven. The fatty acids thus separated possess the following characters: � Iodine value, 83 to 92; acid value, 195 to 205; melting point 21� to 28� C.; refractive index at 40� C., 1.4540 to 1.4580." Br. 

Olive oil soda soap (Sapo), otherwise called Castile or Spanish soap, is a hard soap, and is presented under two principal varieties, the white and the marbled. White Castile soap, when good, is of a pale yellowish-white color, incapable of giving an oily stain to paper, devoid of rancid odor or strong alkaline qualities, and entirely soluble both in water and in alcohol. It should not feel greasy, nor grow  moist, but, on the contrary, should become dry by exposure to the air, without exhibiting any saline efflorescence. This variety of soap contains about 21 per cent, of water.

Sometimes it contains a larger proportion of water, with which the soap is made to combine by the manufacturer, with the fraudulent intention of increasing its weight. Soap thus adulterated is known by its unusual whiteness, and by its suffering a great loss of weight in a dry air. Marbled Castile soap is harder, more alkaline, and more constant in its composition than the other variety. It contains about 14 per cent, of water. Having less water than the white Castile, it is a stronger and more economical soap, but at the same time is less pure. The impurity arises from the veins of marbling, consisting of ferruginous matters, as already explained, and from various substances added as make-weights. Soap bubbles have played an important part in the investigations of the subject of surface tension. Sir James Dewar has kept soap bubbles intact for more than a year in an atmosphere free from foreign particles or vibrations. 

Soap is an emulsifying agent of peculiar value in certain cases. Scoville has prepared a stiff jelly-like emulsion of olive oil containing 97 per cent, of oil and only 0.15 Gin. of sodium oleate. (Bull. Pharm., 1915, 141.) The emulsifying action of soap, in connection with its detergent qualities, is due to the hydrolytic effect of water and the colloidal dispersion of the fatty acids. ; , A soap substitute for detergent purposes, which in some respects is superior to soap as a cleansing agent has been proposed by Schneider (D. C., 1916, Ix, 407). It is made as follows: One hundred grammes of soap bark are heated on a water-bath for a half hour with 300 grammes of water, the mixture strained, the liquid mixed with 400 grammes of kaolin and 400 grammes of powdered talcum, and the resulting paste perfumed with any suitable substance. The paste does not froth, but cleanses the hands, it is said, better than ordinary soap. 

Incompatibles.�Soap is decomposed by all the acids, earths, and earthy and metallic salts. Acids combine with the alkali, and set free the fatty acids of the soap; the earths unite with the fatty acids, and separate the alkali, while the earthy and metallic salts give rise, by double decomposition, to an insoluble soap of their base and a saline combination between their acid and the alkali of the soap. Hard waters, in consequence of their containing salts of lime, decompose and curdle soap. They may be rendered soft, and fit for washing, by adding alkali carbonates, hydroxides or berates. 

Uses.�Soap is laxative and antacid. It acts like an alkaline base and was formerly used to some extent internally, but has been entirely superseded by more elegant alkaline compounds, except in laxative preparations. In constipation, particularly when arising from hardened feces in the rectum, a strong solution of soap, especially of soft soap, forms a useful enema. When the latter is used, two tablespoonfuls may be dissolved in a pint of warm water. Externally soap is used in various skin diseases, not merely for its detergent effect, but also to soften the horny layer of the epiderm.

Soap has a distinct if not very powerful antiseptic action. According to Hamilton (J. I. E. C., 1911, iii, 582), it is practically impossible to get a strong enough solution of a hard neutral soap to exercise any distinct germicidal effect, but if free alkali be present it is much more active. Davis and Swartz (J. A. M. A., December 11, 1921, Ixxvii) find that sodium oleate has a definite value against the gonococcus. Attempts have been made to increase the germicidal value of soap by the addition of various disinfecting agents, especially cresol and mercuric iodide. The practical value of these soaps, however, is open to question; Wildman (Ph. Era, 1919, Iii, p. 123) after bacteriological tests came to the conclusion that although the mercuric iodide soap had a distinct disinfectant action, for practical purposes the tincture of green soap had a greater sterilizing effect upon the hands. 

In pharmacy, soap is frequently employed for the purpose of giving a proper consistence to pills; but care must be taken not to associate it with a substance which may be decomposed by it. It is an excellent emulsifying agent when the mixture is intended for external use. It is also an ingredient in some liniments and plasters. 

In toxicology it is used as a chemical antidote for the mineral acids and the caustic salts of iron, and should always be resorted to in poisoning by these agents, without a moment's delay, and its use continued until magnesia, chalk, or sodium or potassium bicarbonate can be obtained. The mode of administration, in these cases, is to give a teacupful of a strong solution of soap every three or four minutes, until the patient has taken as much as he can swallow. 

Dose, five grains to half a drachm (0.32-2.0 Gm.), given in pill. 

Off. Prep.�Emplastrum Saponis, Br., N. F.; Linimentum Saponis, U. S., Br.; Linimentum Chloroformi (from Soap Liniment), U. S.; Pilulas Aloes, U. S.; Pilulae Aloes et Asafetidss, N. F.; Dentifricium, N. F.; Lavatio On, N. F.  Br. 

Sapo Animalis. Br

 Curd Soap is soap made from sodium hydroxide and purified animal fats consisting principally of stearin; it contains not more than 30 per cent, of water." Br. 

Sapo sebacinus; Sapo domesticus; Sapo Vulgaris; Animal Soap, Tallow Soap, Stearin Soap; Savon animal, Fr.; Haus-seife, Talgseife, Stearinseife, .Sapone animale. It.; Jabon animal, Sp. 

The British Pharmacopoeia, 1914, has retained curd soap in its list, and thus describes it: "Yellowish-white or greyish-white; nearly inodorous; easily moulded when heated, becoming horny and pulverisable when dried. Sparingly soluble in cold water; completely soluble in hot water; soluble in alcohol (90 per cent.). When 5 grammes of the dried and powdered Soap are dissolved in 50 millilitres of boiling alcohol (90 per cent.), and the solution filtered while hot, the filter being thoroughly washed with more of the boiling alcohol, the filtrate is neutral to solution of phenolphthalein (absence of alkaline hydroxides and free fatty acids), and if the filter is then washed with hot water, the washings require for neutralisation not more than 5 millilitres of N/10 solution of sulphuric acid, solution of methyl orange being used as indicator (limit of alkaline carbonates). 

Does not impart a greasy stain to white unglazed paper (absence of free fats). Loses not more than 30 per cent, of its weight when dried at 110� C. Ash not deliquescent (absence of potassium soap)." Br.  Soap made from animal oils and fats is very largely used for all domestic purposes; it was long used for making solid opodeldoc, but is now replaced by sodium stearate. (See Lini-mentum Saponato-Camphoratum, N. F., Part III.) 

Off. Prep.�Linimentum Potassii lodidi cum Sapone, Br. 

SOFT SOAP Sapo Moll. [Green Soap] 

Soft Soap is soap made from potassium hydroxide and olive oil." Br. 

Sapo Viridis, U. S. P. 1880; Savon Noir, Savon mou, Fr.; Sapo Kalinus, P. Q.; Kaliseifc, Schmicrseite, G.; Sapone di potassa, It. 

Linseed Oil, 400 Gm.; Dekanormal Solution of Potassium Hydroxide, 29 cc.; Dekanormal Solution of Sodium Hydroxide, 110 cc.; Glycerin, 50 cc.; Water, a sufficient quantity, to make 1000 Gm. Mix the dekanormal solutions, with the oil and enough water to make the product weigh 925 Gm. Heat the mixture to boiling with frequent stirring, add the glycerin and continue the boiling until the mixture becomes transparent and a portion dissolves completely in hot water, producing a clear solution. Then add sufficient hot water to make the Soap weigh 1000 Gm. and allow to stand with little stirring until the water is absorbed. 

NOTE.�The 29 cc. of dekanormal solution of potassium hydroxide directed above may be replaced by 19.14 Gm. of 85 per cent, potassium hydroxide and the 110 cc. of dekanormal solution of sodium hydroxide may be replaced by 48.89 Gm. of 90 per cent, sodium hydroxide, dissolving the hydroxides in 100 cc. of water. If upon assay the potassium and the sodium hydroxides are found to be of any other strength, a proportionately larger or smaller quantity should be taken. U. S. 

For more than one hundred years, under the name of "green soap," there has been used in Europe a soap made by saponifying linseed, rape seed, or other vegetable oils with various refuse oils, usually including fish oils an excess of potassium hydroxide, and a little sodium hydroxide. The green color of this soap was probably due to the presence of chlorophyll in the impure vegetable oils used. This green soap, or so-called " German soap," was formerly imported into America, but at present has been almost entirely superseded by soft soap made in this country, from which it does not differ in the nature of its active constituents or in its therapeutic properties. 

Both the British and U. S. Pharmacopoeias differ with the common practice and with each other in the formulas for soft soap. The Br. has for many years employed olive oil. The U. S., 1890 and VIII employed linseed oil, but in the 9th Revision experiment was made of using cottonseed oil. This, however, not proving satisfactory, the present U. S. has returned to linseed. If a green soap be wanted, it may be made by the process given in the U. 8. D., 19th edition, p. 1093. 

The soft soap of France, formerly the savon vert of the French Codex, has a greenish color, and usually the consistence of a soft ointment. It is made of hemp seed oil, or sometimes of the dregs of olive oil, and potassium hydroxide. G. M. Beringer (Proc. A. Ph. A., 1903, 420) prefers to use Malaga olive oil in making green soap, and M. I. Wilbert (Proc. A. Ph. A., 1904, 228) extracts the green coloring matter from hemp seed by macerating 25 parts of ground hemp seed with alcohol and obtains 100 parts of a tincture; by substituting an equal measure of this tincture for the quantity of alcohol used in the official process, a green soap can be made, which will have the color which is regarded by some as a very important characteristic. 

Description and Physical Properties.
A. soft, Unctuous, yellowish-white to brownish-yellow mass, having a slight, characteristic odor and an alkaline taste. An aqueous solution of Soft Soap is alkaline to litmus paper and phenolphthalein T.S. "Dissolve about 5 Gm. of Soft Soap, accurately weighed, in 100 cc. of hot neutralized alcohol, collect the residue, if any, on a filter, thoroughly wash it with hot neutralized alcohol, and dry it to constant weight at 100� C. The weight of the residue does not exceed 3 per cent, of the weight of Soap taken. The combined filtrate and washings, on the addition of 0.5 cc. of phenolphthalein T.S. and titration with tenth-normal sulphuric acid, shows not less than 0.1 per cent, and not more than 0.25 per cent of KOH. Each cc. of tenth-normal sulphuric acid corresponds to 0.00561 Gm. of KOH. 

"A solution of Soft Soap in hot distilled water (1 in 20) is nearly clear. Soft Soap loses not more than 52 per cent, in weight when tested for water as directed under Sapo." U. S. "Yellowish-white to green; of an unctuous consistence. Nearly inodorous. Readily soluble in alcohol (90 per cent.), leaving not more than 3 per cent, of insoluble residue. Responds to the tests for alkaline hydroxides and carbonates and for free fatty acids described under ' Sapo Animalis.' Does not impart a greasy stain to white unglazed paper (absence of free oil). Ash very deliquescent, and yields no characteristic reactions for copper.  The mixed fatty acids, liberated and treated as described under ' Sapo Durus,' possess the characters there specified." Br. 

Uses.�Soft soap possesses not only the detergent properties of neutral soaps, but because of the excess of alkali has active medical virtues, especially as a topical remedy. In the first place it removes the fat more thoroughly from the skin and is therefore of service in those forms of skin diseases accompanied with disturbances of sebaceous secretion, such as seborrhea or comedo. It has also the property of softening the keratin elements of the epiderm, and is therefore useful in conditions accompanied with crusts and scales, such as psoriasis and chronic eczema. Because of its local irritating action it may also be used as a stimulant in acne vulgaris and rosacea. It is also asserted to be of adjuvant service in the treatment of various parasitic skin diseases. Kappesser (Fort. Med., 1912) has reported favorable results from the use of inunctions of one-half to one drachm (2-3.9 Gm.) of soft soap in scrofulous lymphadenitis. Kuelbes (Th. M., 1914, xxviii) has found it of occasional benefit also in a large variety of other conditions, especially cardiac neuroses and migraine. In chronic bronchitis and dyspepsia he asserts the inunctions often improve the general condition of the patient, but in asthma they usually were without influence. 

Off. Prep.�Linimentum Saponis Mollis, U. S. (Br.); Linimentum Saponis Mollis Compositum, N. F.; Unguentum Sulphuris Compositum, N. F.; Pasta Betanaphtholis, N. F.

See also: Soaps, Beasley 1872