THE ORIGIX OF SOAP. 23 



near the coast, as in Italy and Spain for example, and this mixt- 

 ure would be Castile soap, which is still largely made by com- 

 bining refuse or inferior olive oil with the soda obtained from 

 the ashes of seaweed. 



The primitive soap-maker would, however, encounter one 

 difficulty that arising from the fact that the potash or soda 

 obtained by simple burning of the wood or seaweed is more or 

 less combined with carbonic acid, instead of being all in the 

 caustic state which is required for effective soap-making. The 

 modern soap-maker removes this carbonic acid by means of 

 caustic lime, which takes it away from the carbonate of soda 

 or carbonate of potash by simple exchange i.e., caustic lime 

 plus carbonate of soda becoming caustic soda plus carbonate of 

 lime, or carbonate of potash plus caustic lime becoming caustic 

 potash plus carbonate of lime. 



How the possibility of making this exchange became known 

 to the primitive soap-maker, or whether he knew it at all, 

 remains a mystery, but certain it is that it was practically used 

 long before the chemistry of the action was at all understood. 

 It is very probable that the old alchemists had a hand in this. 



In their search for the philosopher's stone, the elixir of life 

 or drinkable gold, and for the universal solvent, they mixed 

 together everything that came to hand, they boiled everything 

 that was boilable, distilled everything that was volatile, burned 

 everything that was combustible, and tortured all their " sim- 

 ples" and their mixtures by every conceivable device, thereby 

 stumbling upon many curious, many wonderful, and many use- 

 ful results. Some of them were not altogether visionary 

 were, in fact, very practical, quite capable of understanding 

 the action of caustic lime on carbonate of soda, and of turning 

 it to profitable account. 



It is not, however, absolutely necessary to use the lime, as 

 the soda plants when carefully burned in pits dug in the sand 

 of the sea-shore may contain but little carbonic acid if the 

 ash is fluxed into a hard cake like that now commonly pro- 

 duced, and sold as " soda ash." This contains from 3 to 30 

 per cent, of carbonate, and thus some samples are nearly caus- 

 tic, without the aid of lime. 



As cleanliness is the fundamental basis of all true physical 

 refinement, it has been proposed to estimate the progress of 

 civilization by the consumption of soap, the relative civiliza- 

 tion of given communities being numerically measured by the 

 following operation in simple arithmetic : Divide the total 



