SOAP SOAP-BERRY 



as a detergent in washing clothes ; when an alka- 

 line earth, or oxide of a common metal, as litharge, 

 is the salinable base, the compound is insoluble in 

 water. Fats are composed of a solid substance, 

 called stearine, and n liquid substance, called ela'ine. 

 When they are treated with a hot ley of potash or 

 soda, their constituents react on one another, so as 

 to generate the solid, pearly matter, maroaric acid, 

 and the fluid matter oleic acid, both of which enter 

 into a species of saline combination with the alkali, 

 while a third matter, the sweet principle, remains 

 free. Common soap is therefore a mixture of an 

 alkaline margarate and oleate, in proportions deter- 

 mined by the relative proportions of the two acids 

 producible from the peculiar species of fat. Soap 

 formed from vegetable oil is chiefly an oleate. All 

 oils or fats do not possess, in an equal degree, the 

 property of saponification. Those which saponify 

 the best are the following: 1. oil of olives and of 

 sweet almonds ; 2. animal oils, as hog's lard, tallow, 

 butter, and horse oil ; 3. oil of colza, or rape-seed- 

 oil; 4. oil of beech-mast and poppy-seed, when 

 mixed with olive-oil or tallow; 5. the several fish- 

 oils; 6. hempseed-oil ; 7. nut-oil and linseed-oil; 

 8. palm-oil; 9. rosin. In general, the only soaps in 

 commerce are those of olive-oil, tallow, lard, palm- 

 oil and rosin. A species of soap can also be formed 

 by the union of bees- wax with alkali ; but this has 

 no detergent application, being used only for paint- 

 ing in encaustic. The specific gravity of soap is in 

 general greater than that of water. Its taste is 

 faintly alkaline. When subjected to heat, it 

 speedily fuses, swells up, and is then decomposed. 

 Exposed to the air, in thin slices, it soon becomes 

 dry ; but the whole combined water does not leave 

 it, even by careful desiccation on a sand-bath. 

 Soap is much more soluble in hot that in cold water. 

 This solution is instantly disturbed by the greater 

 number of acids, which, seizing the alkali, either 

 separate the fatty principles, or unite with them in 

 a soapy, acidulous emulsion. The solution is like- 

 wise decomposed by almost all the earthy and 

 netallic salts, which give rise to insoluble com- 

 pounds of the oleic and margaric acids, with the 

 salifiable bases. Soap is soluble in alcohol, and in 

 larger quantity by the aid of heat. When boiling 

 alcohol is saturated with soap, the liquid, on cool- 

 ing, forms a consistent transparent mass, of a yel- 

 low colour. When it is dried, it still retains its 

 transparency, provided the soap be a compound of 

 tallow and soda. Marseilles white soap is com- 

 posed of 



Soda, 6- 



Oil, 60- 



Water, 34- 



Castile soap of 



Soda, 9- 



Well-dried oily matter 76'5 



Water, with a little colouring- matter, . .14-5 



The art of soap-making consists principally in 

 knowing how to determine, from the appearance of 

 the paste, and other circumstances, what kind of 

 lixivium should be employed during each step of 

 the operation. This is done, ordinarily, by obser- 

 vation and experience. The form and size of the 

 bubbles, the colour of the paste, the volume of that 

 which is thrown out on the side of the vessel, the 

 consistence of the matter, and its disposition to 

 swell, as well as the appearance of the steam all 

 furnish criteria by which to regulate the process. 

 It sometimes happens that the paste, though ap- 

 parently very firm, yet, when set in the cold air to 



harden, throws out much water, ;md is resolved into 

 small grains, possessing little consistency. In this 

 case, it is evident that the ley is in excess, and 

 must be separated by means of common salt. Fre- 

 quently, also, the paste becomes greasy, and the 

 oil appears to separate from the soda. As this, in 

 general, proceeds from the paste not being imbued 

 with sufficient water to keep it in combination, it 

 is necessary to add to it a portion of water, or very 

 weak lixivium, to remedy this defect. Potash is 

 employed as follows, in the manufacture of hard 

 soap : A ley of this alkali, rendered caustic by 

 quicklime, is used in the saponification, and to the 

 soft soap which results is added common salt, or a 

 kelp ley, which supplies abundance of muriate of 

 soda. The muriatic acid goes to the potash, to 

 form muriate of potash, which dissolves in the wa- 

 ter, and is drawn off in the spent ley, while the 

 soda enters into combination with the fat, and forms 

 a soap, which, on cooling, becomes solid. Two 

 tons of tallow, properly saponified, should yield 

 three tons of marketable white soap. The adulte- 

 rations most commonly practised on soap are the 

 following : When the soap is made, much water 

 is added, which renders it white. Frequently, 

 pulverized lime, gypsum, or pipe-clay, are incorpo- 

 rated with it. The former of these frauds is readily 

 discovered by the rapid loss of weight which the 

 soap suffers on exposure to a dry air. The second 

 is as easily detected by solution in alcohol, when 

 the earthy matters fall down. 



Soft Soaps. The compounds of fats or oils with 

 potash remain soft, or at least pasty. Three kinds 

 of these are known in commerce the soaps from 

 rape-seed, and other oleaginous seeds, called green 

 soaps, toilet soaps, made with hog's lard, and com- 

 mon soft soap, made with animal fat. In the manu- 

 facture of the common and green soaps, the art 

 consists in effecting the combination of the oil with 

 the potash, without the soap ceasing to be dissolved 

 in the ley ; while, on the contrary, in the fabrica- 

 tion of hard soap, it is necessary to separate the 

 soap from the ley, even before the saturation of the 

 oil is accomplished. It contains more alkali than 

 is absolutely necessary for the saturation of the oil. 

 It is, in fact, a perfect soap, dissolved in an alkaline 

 ley. It may readily be converted into hard soap by 

 the addition of common salt. Toilet soaps, made 

 with hog's lard and potash, should have as small an 

 alkaline excess as possible. The finer soaps for the 

 toilet are made with oil of almonds, with nut-oil, 

 palm-oil, suet or butter. They are either potash 

 or soda soaps, as they may be preferred in the solid 

 or pasty states. 



SOAP-BERRY (sapindm). These trees some- 

 what resemble the hickories or walnuts in their 

 foliage, but are widely different in their fruit and 

 botanical characters. The fruit is globular, as 

 large as a cherry, enclosing a nut of a shining black 

 colour when ripe. The pulp serves as a substitute 

 for soap in washing linen, but is very apt to burn 

 and destroy it, if used too frequently. The nuts 

 are very hard, black, and finely polished, and are 

 used for beads. Formerly, they were imported into 

 Europe for waistcoat buttons, and were sometimes 

 tipped with silver or other metals. They were 

 very durable, as they do not wear, and seldom 

 break. The whole plant, especially the seed-ves- 

 sel, being pounded and steeped in ponds, rivulets or 

 creeks, is observed to intoxicate and kill the fish. 

 The wood is white, and full of a gum, in odour and 

 taste resembling copal. The flowers are disposed 



