24 SCIENCE IN" SHORT CHAPTERS. 



quantity of soap consumed in a given time by tlie total popu- 

 lation consuming it, and the quotient expresses the civilization 

 of that community.* 



The allusion made by Lord Beaconsfield, at the Lord 

 Mayor's dinner in 1879, to the prosperity of our chemical 

 manufactures was a subject of merriment to some critics, who 

 are probably ignorant of the fact that soap -making is a chemical 

 manufacture, and that it involves many other chemical manu- 

 factures, some of them, in their present state, the results of 

 the highest refinements of modern chemical science. 



While the fishers of the Hebrides and the peasants on the 

 shores of the Mediterranean are still obtaining soda by burning 

 seaweed as they did of old, our chemical manufacturers are 

 importing sulphur from Sicily and Iceland, pyrites from all 

 quarters, nitrate of soda from Peru and the East Indies, for 

 the manufacture of sulphuric acid, by the aid of which they 

 now make enormous quantites of caustic soda from the material 

 extracted from the salt mines of Cheshire and Droitwich. 

 These sulphuric acid works and these soda works are among 

 the most prosperous and rapidly growing of our manufactur- 

 ing industries, and their chief function is that of ministering 

 to soap-making, in which Britain is now competing triumphant- 

 ly with all the world. 



By simply considering how much is expended annually for 

 soap in every decent household, and adding to this the quan- 

 tity consumed in laundries and by our woollen and cotton 

 manufacturers, a large sum total is displayed. Formerly, we 

 imported much of the soap we used at home ; now, in spite of 

 our greatly magnified consumption, we supply ourselves with 

 all but a few special kinds, and export very large and continu- 

 ally increasing quantities to all parts of the world ; and if the 

 arithmetical rule given above is sound, the demand must stead- 

 ily increase as civilization advances. 



* The scientific pedant of the Middle Ages displayed his profundi- 

 ty by continually quoting Ajristotle and other " ancients." His mod- 

 ern successor does the like by decorating his pages with displays of 

 algebraical formula. In order to secure the proper respect of my 

 readers I here repeat the equation that I enunciated many years ago, 

 " c = -" where c stands for civilization, s for the quantity of soap con- 

 sumed per annum, and p the population of a given community. 



