19151 Resin Acids — A Coreection 161 



from water solutions of their potassium salts by acidifying with 

 hydrochloric acid. 



To test these ideas, a perfectly fresh specimen of the oleo- 

 resin of Pinus Heterophylla (Cuban or slash pine) was obtained 

 from Florida. Five grams of this specimen were dissolved in 

 50 cc. of ether, the solution filtered and the potassium salts of 

 the acids immediately precipitated by slowly adding 10 cc. of 

 a very concentrated water solution of potassium hydroxide, ap- 

 proximately 15 normal, a salting-out process. This precipitate, 

 freed as far as possible from the potassium hydroxide solution 

 by draining, was thoroughly mixed with glass wool to make the 

 mass more permeable to the extractive, and extracted with ether 

 one hundred hours in a Soxhlet extractor until no further traces 

 of spirits of turpentine or resene could be detected in the fresh 

 extract. The extracted mass was treated with cold water and 

 the solution of the potassium salts filtered from the glass wool. 

 The free acids were precipitated by slow addition of dilute 

 hydrochloric acid, just to acidity, filtered upon a Buchner fun- 

 nel, washed with water until free from chlorides, and rapidly 

 dried as far as possible with the suction pump. The partly 

 dried acids were dissolved in ether and the removal of water 

 completed by addition of freshly ignited sodium sulfate. This 

 solution was rapidly filtered into the heating flask in which the 

 experiment was to be conducted. 



This flask had been previously filled with nitrogen obtained 

 by drawing air successively through a water solution of am- 

 monia; over heated copper; through dilute sulfuric acid; two 

 wash bottles containing alkaline pyrogallic acid solution; con- 

 centrated sulfuric acid and two drying tubes — one containing 

 calcium chloride and soda lime, the other phosphorus pentoxide 

 mixed with pumice. The heating flask, surroimded by a bath of 

 cottonseed oil in a beaker, contained a thermometer, and its 

 outlet tube, during the heating experiment, dipped below the 

 surface of freshly filtered barium hydroxide solution in the 

 precipitating flask. A tube of soda-lime was placed between the 

 precipitating flask and the aspirator. 



The ether solution of the resin acids was evaporated to 



