DERIVATIVES OF ALCOHOLS AND ACIDS 65 



(b) Add an equal volume of soap solution to the unboiled acid car- 

 bonate solution and to the filtrate from the portion that was boiled. 

 Notice the difference. The precipitate formed with the soap and acid 

 carbonate solution is the calcium salt of palmitic or other fatty acid. 

 Water containing calcium acid carbonate in solution is termed hard. 

 This hardness is termed temporary because it is destroyed by boiling 

 and precipitating out the calcium, (c) Test solutions of magnesium 

 sulphate and calcium sulphate in the same way with soap solution 

 without boiling and after boihng. Is there any change in the boiled 

 solution? Water containing these salts in solution is termed per- 

 manently hard. 



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