As regards actual manipulation, it was found best 

 to add the excess of caustic soda to the hot ex- 

 tract, so that precipitation of the soap took place 

 rather slowly as the solution cooled down. Very 

 strong alkali above 10 per cent NaOH gave 

 somewhat syrupy solutions, with increased contam- 

 ination of the soap by humus and without appre- 

 ciable gain in the quantity of soap precipitated. 

 The soap precipitate proved difficult to filter. The 

 liquor was separated by draining or syphoning. 

 With this procedure the soft precipitate retained an 

 appreciable quantity of liquor. The bulk of the 

 humus was removed from the soap by dissolving 

 the same in the minimum amount of hot water 

 and salting out again with caustic soda. 



To determine the power of caustic soda in salting 

 out rosin soap, a series of experiments were carried 

 on with pure rosin on a quantitative scale. The 

 results are summarized in Figure 1. 



Clear, bright rosin, prepared by extracting a 

 good grade of paper-maker's rosin with ether, was 

 powdered and dissolved in a slight excess of warm, 

 dilute caustic soda solution. Separate portions of 



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