An Bffay on Bleaching, 25$ 



by potafh. Soda gives a hard foap; potafh, on the other 

 hand, a foft kind. Pliny afcribes to the Gauls the invention 

 of this valuable compofitiou. The foap of our anceftors was 

 formed of goat's greafe mixed wiih the afhes of beech wood ; 

 and feveral improvements were fuceeflively introduced into 

 the manufacturing of this fubftance, as chance, the mother 

 6f the moil important difcoveries, pointed out the neeeffity 

 of them. The progrefs of the arts towards perfection has 

 been very (low, on account of the prejudices of that ignorance 

 which prevailed in the pad ages. We have, however, now 

 reached a period when the lciences and the arts, aided by 

 their reciprocal refources, are advancing rapidly towards a 

 certain degree of perfection. 



In France, two kinds of foap only are made — hard foap, 

 and foft foap : the firft with foda and olive oil; the feeond 

 with potafh, and vegetable oils of lefs value. 



In Hungary, foap is made of tallow and natron ; as is the 

 cafe in feveral parts of Germany and Ruflia. The Ruflians 

 make a hard foap alfo with bad fait butter ; but this kind i> 

 not much efteemed ; its rancidity and the quantity of fait and 

 cafeous matter found in it degrade its quality. Wiegleb afTerts 

 that a very hard foap, which has a very agreeable fmell of al- 

 monds, is made with yellow and white wax. 



The Englifh, as they have not vegetable oils in abundance, 

 make foap onlv with tallow or fifh oil, fometimes with kitch- 

 en-fluff or fpoilt butter. They have four kinds. lit, White 

 foap, made with foda of Alicant, or the foda of Varech, and 

 tallow. 2d, Marbled foap, made of tallow and kitchen- fluff. 

 The marbled appearance does not arife from an oxide, as 

 among us, but becaufe a little of the ley is difperfed through- 

 out the whole mafs. - 3d, A hard yellow kind of foap, com- 

 pofed of foda, tallow, and refin. This la(l fubftance is intro- 

 "duced only for the purpofe of rendering the foap cheaper, but it 

 certainly does not augment itsdeterfive ftrength. The fourth 

 kind of foft foap is formed of whale or fifh-oil and potadi. 



It was long an object of refearch to difcover fubflanees- 

 which might be fubftituted for oil and tallow in the fabrica- 

 tion of foap. It was refcrved for Chaptal to lay open this 

 field by his important difcovery of a procefs for fapontfyitfg 

 wool, and converting into excellent foap rags of old cloth 

 and worfted, the watte of carding, and the other refufe of 

 "cloth manufactories. This difcovery gave rife to that of fir 

 John Dalrymplr, who fuppofed that, by a method fimilar to 

 • that of Chaptal, it would be poffible to convert the mufcular 

 -part of fat fifh into foap; and fonie experiments, crowned 

 with complete fuccefs, foon confirmed him in this idea. 

 : * Thofc 



