the variaus Kinds of Soap. I H 



•4. Soft Soap, is made with whale or fifli oil ; but I am not acquainted with the proportion 

 Ufed. The procefs for making it differs from that of hard foap, in this circumftance, that 

 none of the ley is drawn off, but the whole is allowed to combine with the foapy compound. 

 On this account, it is neceffary to ufe a pretty pure alicali, particularly that it fhould be free 

 from fea-falt, which is a fubftance of the greateft detriment, as it caufes the foap to feparate 

 from the ley, and rife to the top of the veffel. The oil and alkali (which muft be pot-afh) 

 are boiled together, imtil a combination has taken place; then a quantity of tallow is added, 

 which, by particular management, is difperfed through the foap, in the form of white fpots, 

 giving it a beautiful appearance *. 



Having thus curforily mentioned the principal kinds of foap manufaftured in different 

 countries, I will now, in as few words as poflible, ftate the procefs followed in this country, 

 for making common white foap. This will enable us to judge with more certainty of the 

 plan lately propofed for making hard foap, by mixing the mufcular fibre of fifli with the 

 tallow. 



Procefs for making JVh'ite Soap, 



The tallow is firft melted in the veffel with weak barilla ley, the mixture is then gradually 

 brought to a boiling heat, and we continue adding alkali, until the whole of the tallow has 

 formed a faponaceous compound. We know this has taken place, if the compound has a 

 milky appearance, with a confiderable degree of confiftence, and feems to be feparating from 

 the liquor below. This feparation is a very material part of the operation ; and to effedl it 

 completely, a quantity of fea-falt, or weak kelp ley, is added, the materials are continued boil- 

 ing for two or three hours, and then the fire is withdrawn. The foap will now be found 

 united at the top of the liquor, or what is called the wajie Ityfy which is of no further ufe, 



and 



* I fliould be happy to learn the proportions ufed in foft foap making, and alfo the particular management 

 of the tallow in producing the white fpots ; and if this tallow be of any fervite. 



+ The ley which is found below the foap, and known under the name of wafte ley, is of a v'ery mixed 

 nature, and the variety is much increafed, according as potafli, barilla, or kelp, are ufed in the manufafture. 

 Several fubftances always occur, whatever be the nature of the faline compound employed. Thefe are, 



1. Gelatine. A confiderabk quantity of this fubftance (which had been previoufly combined with the taK 

 low) is found in folutioD, or fufpended in the ley: the cauftic alkali has fo ftrong an a£lioa upon it, that a 

 portion is decompofed, the hydrogen and azote flying off in the form of ammonia, while the carbonaceou* 

 matter remains behind, giving a dark blue, or blackilh colour, to the undecompofed gelatine. 



2. As tallow contains febacic acid, it unites with the alkali, and fometimes with the lime, forming febats. 



3. Carbonai, or uncombineU alkali. However accurately the manufailurer works, ftill a quantity of the 

 alkali efcapes, and is found in the wafte ley. Befides the fabftances we have already mentioned to be com- 

 mon, other combinations occur. Thus if kelp be ufed alone, in making the foap, befides the gelatine, &c. 

 the ley contains muriate of foda, fulphate of foda, fulphurets of foda, and potalh. As potafh is never worked 

 by itfelf in making hard foap, but generally with kelp (at leaft in Scotland), we obtain different faline com- 

 binations ; thefe are muriate of potaih, muriate of foda, and fulphate of foda ; but this laft is in fmall quantity : 

 fulphuret of foda alfo occurs. If barilla is employed, we have muriate of foda, fulphate of foda, and fulphurets 

 of foda, in the ley. The nature of the faline compounds found in barilla ley, are often confiderably different 

 from what has been now mentioned ; particularly, when the foap is made with Caulonia barilla. This it 



owing 



