THE PATS. 27 



53. To about 10 grammes (11 cubic centimeters) of 

 olive-oil add 20 cubic centimeters of 10-per-cent. potassium 

 hydrate solution. Boil the mixture, gently stirring mean- 

 while, until the odor of the oil has largely disappeared and 

 it appears homogeneous and no oil separates when a few 

 drops are poured into water. This may require fifteen 

 minutes to half an hour. Add water as it evaporates, to 

 keep the original volume. The product is a mixture of 

 potassium soap and glycerin. 



54. Convert a portion of the soap into the sodium 

 or hard soap by adding some saturated salt solution and 

 allowing it to stand until cold. It will dissolve on warm- 

 ing. 



55. To another portion add a calcium solution. A 

 calcium soap is formed which is insoluble in water. It is 

 this compound which is produced by the action of soap on 

 "hard water." Many of the heavy metals give similar 

 compounds. Try it with solutions of iron, lead, copper, etc. 



56. To the remainder of the potassium soap solution 

 add sulphuric acid slowly until it is plainly acid to test- 

 paper. The fatty acids are set free as insoluble substances, 

 the glycerin remaining in solution. Filter out the acids 

 by means of a wet filter-paper, through which they will 

 not pass. Save the filtrate for the extraction of the glyc- 

 erin. Wash out the sulphuric acid with distilled water 

 until the wash-water is no longer acid, and try the reaction 

 of the fatty acids with litmus-paper. They are acid to 

 litmus. 



57. Dissolve the fatty acids in hot alcohol, let this 

 cool slowly, observe and sketch the crystals. 



58. Allow the fatty acids to stand until the water has 

 drained off or dry them by the aid of filter-paper. Heat them in 



