SOFT SOAPS 233 



CHAPTER XXIII 

 Softening Water for Sprays — Soft Soaps 



In making up sprays and washes containing soft soap it is 

 desirable to soften water which is at all hard, in order to avoid the 

 considerable loss of soap otherwise involved. This is done by the 

 addition of washing-soda — NaaCOg. 10H2O. Permanent hardness 

 due to sulphates, etc., is removed as follows : — 



CaS04 + Na2C03 = CaC03+ Na2S04. 



Temporary hardness, due to bicarbonates, also responds to the 

 treatment, the bicarbonate being reduced to normal carbonate 



Ca(HC03)2+Na2C03 = CaC03 + 2NaHC03. 



Hard waters containing much magnesium do not respond so well 

 to softening with sodium carbonate. 



223. {a) The total hardness of a water is determined 

 as in 222 {b), p. 230. For each part of CaCOs per 100,000 

 is added to the water 2-9 parts of washing-soda and the 

 hardness again determined. 



(J?) Softeni7Zg Water for snaking Soap Sprays and 

 Washes. — To avoid loss of expensive soap in working 

 with a hard water, the following method is adopted : — 

 For each "degree of hardness" (i grain CaCOg per 

 gallon) is added 2-86 grams of washing-soda per gallon. 

 For each part CaCOg per 100,000 is added 2-0 grams 

 washing-soda per gallon. 



Thus, to soften lOo gallons of a hardish water of 20 

 degrees of hardness, one would require 

 TOO X 20 X 2-86 grains 



= 5720 grains = 13 oz. washing-soda. 



To soften the same 100 gallons of water with soft soap 

 of good quality, i.e. to produce a lather, would require 

 3J-4 lbs. The relative prices and quantity required of 



