SOAP. 



This wMght of barilla, at the prefent price, cofts lol. ^s. : 

 192 lbs. of potaOi will now coft 61. \']s. ; and 126 lbs. of 

 common fait, i/. 17/. Thefe two fums are 8/. i+f. The 

 faving, therefore, in employing potalh and common fait, in 

 making even the beft hard white foap, inftead of barilla, u 

 nearly 5 per cent. But if the two alkalies ' are to be con- 

 tained in equal proportions, then about half the common 

 fait only need be ufed, and the faving will be very confider- 

 able. It will alfo appear evident, that foap may be made 

 of any degree of hardnefs, by ufing more or lefs of common 

 fait with the potafh ; and that if no fait at all be ufed, the 

 foap will be foft. 



The difference of price between barilla and potafh is often 

 much more than at prefent in favour of ufing potafh : this 

 will make the faving above mentioned more confpicuous. 



It mutt alfo be remembered, that fome fait is always ufed 

 for the purpofe of feparating the fpent leys from the foap. 

 This has been ftated at about three-quarters of a cwt. to 

 Z4 cwt. of foap. It feems that a folution of fait of this 

 flrength does not diffolve foap. 



Hard Soap, TellvM. — This foap is formed of fimilar 

 proportion? of foda and tallow with the lall ; but it alfo 

 contains rofin, and fometimes palm oil. 



The following are the average proportions of the ma- 

 terials for making yellow foap, which may be relied upon. 



The whole weight of the materials, exclufive of the lime, 

 and the refufe of the potafh and barilla, is equal to 

 24 cwt. o qr. I lb. ; the foap, independent of the water it 

 contains, is 18 cwt. o qr. 25 lbs.: this, taken from 24cwt. 

 oqr. I lb. leaves 5 cwt. 3qr. 4lbs. for the refufe of the tallow, 

 rofm, and palm oil. That the tallow mull make much wafte 

 will be eafily conceived, from the mod inferior kind being 

 ufed. The roGn and oil muft alfo yield much refufe. This 

 refufe is found all tojjether at the bottom of the pan after 

 boiling, and is known in the manufaftories under the name of 

 nigre. 



In boihng the yellow foap, the rofin, oil, and tallow are put 

 into the boiler firit. The ley is prepared in a fimilar vat, and 

 managed in other refpefts in the fame mode as in forming 

 the white foap. 



The manner too of adding the ley from time to time, and 

 the flirring, arc jnfl kept up in a fimilar way, till the fatty 

 matter is fully faturited. The time required for boiling the 

 quantity of foap ftated above, is fometimes as much as three 

 weeks, during which time it is kept in what is called the open 

 ftate, tiiat is, the watery part is completely feparated from 

 the foap. It would appear that this foap requires merely the 

 prefence of the neutral falls in ley to keep it in the open flate. 

 This arifes probably from this being a lefs perfeft foap, and 

 lefs foluble in water. The foap appears in fmall lumps, 

 perfeftly detached from the fluid. At the end of every 

 day the foap is allowed to cool, when the thin part finks 

 to the bottom : this is fpent ley, and is pumped oft every 

 morning. The fire is again raifed, and frefh leys ^dded : 

 the boiling and flirring go on again. This adlion is re- 

 peated till the fat is faid to be killed. This, as we have 

 obferved, takes fometimes fifteen or twenty days. When 

 this change is complete thi- fire is withdrawn, and the mafs 

 allowed to cool : the lafl ley is pumped out. The addition 

 of a little water, and the fire being raifed, allow the foap 



to be difTolved, and the refufe, which is principally the fab- 

 fiance we have called nigre, is left at the bottom, perfeftly 

 diflinft from the foap. When the foap is of a proper con- 

 fiflence for caking, it is transferred to the moulds, where it 

 is treated in a manner fimilar to that already defcribed in the 

 white foap. 



It is a queflion, whether making this inferior foap is fo pro- 

 fitable to the manufafturer as is fuppofed. It has appeared, 

 that in making the quantity of foap above flated, which is 

 26 cwt. o qr. 21 lbs., there are 5 cwt. 3 qr. 4 lbs. of refufe, 

 which is principally in the nigre. This refufe will be found 

 very trifling in the white foap ; we think not more than ^Vth 

 of the weight of the foap. It will be evident, that in making 

 the yellow foap, a great quantity of matter is ufed which 

 never combines. Would it not be more economical t» 

 purify thefe materials before hand? 



Soft Soap- — This differs in its compofition from hard, in 

 containing no alkali, but potafh. We have feen that hard 

 foap may be made not only with pure foda, as is the cafe in 

 the manufaftories in the fouth of France, but that a tole- 

 rably hard foap, much better fitted for praftice, is made with 

 about equal portions of potafh and foda. 



Soft foap made with colourlefs fat, fuch as tallow, is a 

 white undluous fubflance, about the confiftency of lard. If 

 the fat be coloured, the foap partakes of the fame. In 

 France and other parts of the continent, it is generally 

 coloured, fometimes with metallic oxyds. Thofe made with 

 yellow oil are fometimes coloured with indigo, which gives 

 them a green colour. The oils employed are feWom olive- 

 oil, but the cheaper oils, fuch as rape-oil, the oil of hemp- 

 feed, lint-feed, and others. 



In Holland it was made with whale-oil. This oil was 

 forbidden on fome parts of the continent, on account of its 

 difagreeable fmell. In this country, however, all the foft 

 foaps are made with whale-oil, which gives a tranfparent 

 mafs of a yellow colour. In commerce, however, we do 

 not find it uniform in its colour. Befides the yellovr 

 part, it appears interfperfed with white fpots, giving the 

 whole a ftrong refemblance to the infide of a dried fig. 



The proportions of potafh and oil, for forming foft foap, 

 will be eafily inferred from what has been obferved in the 

 proportions of the other foaps. The white fpccks are pro- 

 duced by adding a portion of tallow to the oil, when the 

 boiler is charged. This addition does not improve the foap, 

 but habit in commerce has rendered it indifpenfable. The 

 ley is prepared by adding to the potafh about three-fourths its 

 weight of quicklime, and the procefs is continued as direded 

 in making the hard foap, ufing the fame apparatus. The ley, 

 when prepared, is to be added to the oil and t allow in the boiler 

 at intervals, fimilar to thofe in making the hard foap, and the 

 flirring kept up in the fame way, till the mafs affunies a 

 proper confiftency. The experienced foap-maker will judge, 

 when the materials are in proper proportions, by the ap- 

 pearance of the foap when boiling ; hence he knows when 

 to ceafe to add more ley. Should a flranger to the- procefs 

 of making either kind of foap have to perform the tafk, 

 he would require to know the proportions in which the 

 alkali ought to bear to the oil. He would weigh his oil or 

 tallow when he put it into the boiler; he will affay his ley 

 by the method laid down in the commencement of this 

 article, and by that means know how much real alkali i» 

 contained in a given meafure of his ley. He will by this 

 means know nearly when he had added a fufficient quantity 

 of ley to faturatc the oil or fat. In the loa)i made with 

 foda, the real alkali muft be to the oil as i to 7.28, and that 

 with all potafli muft be as I to 5.1 nearly. This of courfe 

 will be the proportion for foft foap. When the foft foap is 



of 



