RESINS 25 



of half-normal alcoholic potash were then added and the mixture 

 heated on a steam bath (refluxed) for an hour. The excess of 

 potassium hydroxide was titrated with a half-normal alcoholic 

 solution of hydrogen chloride. A gram of surface resin required 

 approximately 177 milligrams of potassium hydroxide for neu- 

 tralization, while a gram of fossil resin took about 150 milli- 

 grams. The acid and saponification values of various samples 

 of resin were determined. The results showed that darker speci- 

 mens of resin gave higher acid and saponification values than 

 did lighter-colored ones. 



Samples of surface resin were distilled with steam, but only 

 traces of volatile oil were obtained. Fossil resin which was 

 finely pulverized yielded a larger proportion of volatile oil. 

 When steam-distilled in the presence of an alkali, 500 grams 

 of surface resin gave 6.5 grams of oil, while an equal quantity 

 of fossil resin gave 40 grams of oil. The oil obtained by steam 

 distillation when dried over solid potassium hydroxide had a 

 pale-lemon color and pleasant odor. This was fractionally dis- 

 tilled. The main fraction boiled between 155' and 165". By 

 treating with hydrochloric acid gas this fraction was converted 

 into a hydrochloride which crystallized from alcohol and melted 

 at 124' . This substance was identified as pinene hydrochloride. 



A method of analysis devised by Richmond showed that one 

 hundred parts of crude resin gave the following results : 



I'arts. 



Insoluble in absolute alcohol .5 



Soluble in alcoholic potash 40.0 



Insoluble in alcoholic potash 41.5 



Neutral oil soluble in alcohol and volatile with steam . H.O 

 Neutral resin partially soluble in alcohol and non- 

 volatile with steam 10.0 



Water, etc., undetermined 2.0 



These results confirm the conclusion of Tschirch that Manila 

 copal consists mainly of amorphous free resin acids, and contains 

 a neutral resin indifierent to alkalies, and a volatile oil. Rich- 

 mond extracted the resin acids from Manila copal by using a 

 modification of Tschirch's method. An ether extract of Manila 

 copal was treated with 5 per cent ammonium carbonate solution 

 for several days, after which the mixture was acidified. The 

 resin acids were precipitated as an amorphous powder. When 

 this precipitate was dissolved in dilute alcohol and crystallized, 

 white crystals melting at 186 ' were obtained. Analysis showed 

 that these crystals had the molecular formula C,„H,,,02 and that 

 the resin acid was monobasic. 



