SOAP. 



of a proper confiftency for caking, it i« poured into barrels, 

 in which it is fold. 



Soaps, particularly the hard, are frequently reduced in 

 their value, by the fraudulent praftice of keeping them 

 wet. The common or proper ftate is when they contain 

 about 30 per cent, of water ; but they may, by a nefa- 

 rious management, be made to contain 60 per cent, which 

 is a great impofition. This fraud, like many others, is 

 detefted when it is too late. It is found to lofe weight 

 rapidly by expofure to the air. 



Before we clofe this article, we may point out fome 

 means of economizing the ufe of the alkali in foap-making, 

 which, in very extenfive manufaftories, is worth attending 

 to. In the firft place, it fliuuld be obferved, that the fpent 

 leys always contain tree alkali, and it is generally added a 

 fecond time, in order that as much as poflible of it may be 

 taken up. It is found, however, by experience, that fome 

 will ftill be found in folution, which the fat will never 

 take up. This is owing to the fame liquid containing 

 feveral neutral falls in folution. If this liquor be evapo- 

 rated to a certain extent, and fet to cool in Ihallow vefl'els, 

 the neutral falts will cryilallize and feparate from the liquid 

 to a certain extent. The liquid part may then be eva- 

 porated a fecond time, and again cryftaUized. The liquid, 

 after thefe falts have been feparated, may now be added to 

 the fat, and the alkali will combine with it. If barilla or 

 kelp is the alkali, then the liquid ought to have a little 

 lime added, which evaporating, ferves to take the carbonic 

 acid from the foda. Without this precaution the carbonate 

 of foda would cryftallize with the other falts. With potalh 

 this precaution is unneceflary. 



The falts which are feparated from barilla and kelp are 

 chiefly muriate and fulphate of foda. The former may be 

 ufed as a fubftitute for fait in the laft part of the procefs 

 of boiling. The fulphate of foda may be fufed with faw- 

 duft or powdered coal in a reverberatory-furnace. The ful- 

 phuret of foda is produced, from which the alkaU may be 

 recovered. Perfumed foaps are eafily formed by adding 

 the different effential oils while the foap is in a liquid form, 

 but not while very hpt, becaufe the perfume would eva- 

 porate. The faponaceous liquid, called milk of rofes, is 

 formed by mixing the liquid obtained by expofing potaih to 

 the air with rofe- water, and then adding this to oil of almonds, 

 till the mixture becomes milky without being greafy. 



Ball Soap, commonly ufed in the North, is made with 

 lees from aihes and tallow. The lees are put into the 

 copper, and boiled till the watery part is quite gone, and 

 there remains nothing in the copper but a fort of faline 

 matter (the very flrength or eflence of the ley) ; to this 

 the tallow is put, and the copper is kept boiling and ftirring 

 for above half an hour, in which time the foap is made ; 

 and then it is put out of the copper into tubs, or bafliets, 

 with fheets in them, and immediately (whilft foft) made 

 into balls. Note, it requires nearly twenty-four hours, in 

 this procefs, to boil away the watery part of the ley. 



The fimpleft, and upon the whole the mod beautiful, 

 foap, is the fine white foap prepared from olive-oil and 

 foda, extrafted from the bed barilla, which is manufaftured 

 largely in the countries where the olive grows ; particularly 

 in the fouth of France, for which Marfeilles is the molt 

 celebrated, in fome parts of Italy, and in Tripoli. A 

 fimilar, but more expenfive foap, is made of foda and oil of 

 almonds for medicinal purpofes. (See Sapo Jmygdalinus.) 

 What is called in our country " Windfor foap" is of this 

 kind, prepared with either of the above-mentioned oils. 

 Common loap is manufaftured principally by our foap- 

 boilers frofti tallow or any other fat ; and the alkali em- 

 I 



ployed is either barilla or pearl-afh, or a mixture of rfie twft, 

 according to the price and the praftice of the manufadurer. 

 But in order to obtain a ftiff fait, recourfe is had to the 

 action of common fait, as we have already mentioned. The 

 olive-oil, or Marfeilles and other foaps, are fometimes arti» 

 ficially " marbled," or ilreaked throughout their whole 

 fubftanoe with red or blue veins. This foap is harder 

 than the white foap of the fame materials, becaufe it re- 

 quires to be dried to a greater degree in order to take the 

 marbling. This is performed, by adding to the foap, a* 

 foon as it is completely made and feparated from the fpent 

 ley, a frefh quantity of ley, and immediately afterwards a 

 folution of fulphate of iron. A decompofition between 

 the two takes place, and a black oxyd of iron is feparated, 

 which is entangled within the liquid foap. The boiler i» 

 then cooled, and the ley which fettles is drawn off ; after 

 which the foap is again melted. A workman then ftands 

 over the boiler, and ilirs the foap with a wooden inftru- 

 ment, while another throws in at intervals a quantity of 

 colcothar, or brown-red oxyd of iron, ground up with water 

 into an uniform liquid. This diffufes both the oxyds 

 through the foap, which is then cooled and framed. This 

 procefs requires fome manual dexterity, fo that the ingre- 

 dients may be ftirred together, and the marbling fufficiently 

 diffufed through the whole mafs, without mixing it com- 

 pletely. 



Soap is much ufed in wafhing and whitening linens, cleanf- 

 ing woollen cloths from oil, whitening filk, and freeing it 

 from the refinous varnifli with wh'ich it is naturally 

 covered ; and for various other purpofes, by the dyers, 

 perfumers, hatters, fullers, &c. 



The alkaline lixiviums, being capable of diflblving oils 

 more effeftually than foap, might be employed for the 

 fame purpofes ; but when this aftivity is not mitigated by 

 oil, as it is in foap, they are capable of altering, and even 

 deftroying entirely, by their caufticity, moft fubftances, 

 efpecially animal matters, as filk, wool, and others ; whereas 

 foap cleanfes from oil almoft as effeftually as pure alkali, 

 without danger of altering or dellroying, which renders it 

 very ufeful. 



The manufafture of foap in London, firft began in the 

 year 1 524 ; before which time this city was ferved with white 

 foap from foreign countries, and with grey foap, fpeckled 

 with white, from Briftol, and fold for a penny a pound, 

 and alfo black foap for a halfpenny the pound. 



Soap, in the Materia Medica. Soaps, both hard and 

 foft, have been applied to medical ufe. Well made hard 

 foap, fit for medical ufe, has very httle odour, and a 

 naufeous alkalefcent tafte ; is white, and of a firm con- 

 fillence ; does not feel greafy, and is devoid of any faline 

 efflorefcence on the furface. With water it forms a milky 

 opaque folution ; and with alcohol a nearly tranfparent, 

 fomewhat gelatinous, folution. It is decompofed by all 

 the acids, and by many neutral falts, which combine with 

 the alkali and form new compounds ; hence hard water 

 which contains fulphate of lime does not properly diflblve ' 

 foap. According to the experiments of Darcet, Lelievre, 

 and Pelletier, (Hated in the preceding article,) 100 parts of 

 newly made foap confift of 60.94 oil, 8.56 alkali, and 0. 503 

 water : but part of the water is loll: by keeping, and the 

 foap becomes lighter. 



Hard foap, triturated with vegetable refins and thick 

 balfams, incorporates with them into a compound ; foluble, 

 like the foap itfelf, in watery hquors ; hence it proves an 

 ufeful ingredient in refinous pills, which of themfelves are 

 apt to pais entire through the inteilines, but by the admix- 

 ture of foap become diflbluble in the ilomach. It renders 



undluous 



