122 BACON. 



these resins could be gathered if there were a commercial demand for 

 them, and as they do not belong to the present class of varnish gums 

 (fossil resins) the supply would be perpetual. In spite of the advantage 

 ■which balao has in its e.xceedingly tough, durable, and hard coat, it has 

 the very serious disadvantage of drying very slowly. Thus far I have not 

 been able thoroughly to combine it with linsed oil, turpentine, or with 

 other driers to make a quick-drying varnish. Another suggested use for 

 the resin is for the treatment of gonorrhoea a,s a suljstitute for copaiba. 

 A similar, possibly identical, resin is now being shipped from the Malay 

 States for this purpose. 



The distillation of halao presents some difficulty as there is a con- 

 siderable quantity of water mixed with the resin, hence a violent foaming 

 occurs on attempting distillation in vacuo. On running steam through 

 the viscous resin to remove the volatile constituents, the difficulty is soon 

 encountered that after heating for a short time the whole resin becomes 

 very hard and solid, so that steam does not readily penetrate it. These 

 difficulties were overcome by distillation in vacuo from an oil bath with 

 the following arrangement: 



Between the air pump and the receiver a three-waj' stop-cock is inserted. I'liis 

 is arranged to connect the distilling flask with the air pump or with tlie open air. 

 As soon as the resin threatens to foam, a little air is let in through this stop-cock, 

 and thus, by careful manipulation, it is possible to control the distillation until 

 all the water ha/S passed over, after which time there is no difficulty. 



The record of the various experiments made on balao resin is as 

 follows : 



( 1 ) I attempted to dissolve 270 grams of fresh halao resin in 500 cubic centi- 

 meters of ether, with the idea that in this manner the water could be removed and 

 the resin easilj' distilled in vacuo. One hundred and ninety grams were dis- 

 solved and after drying with calcium chloride distilling off the ether, etc., were 

 added to the filtered oil of experiment (2). The insoluble 80 grams was a hard, 

 brittle, yellowish resin, which proved of value in making varnishes. 



(2) One kilogram of balao was treated with 2 liters of ligroin (boiling point 

 60° to 80°). After heating for one hour on a retiux condenser, the solution was 

 filtered. This is a very slow operation, as the paper is clogged by the gummy mass. 

 Two hundred and twenty grams insoluble resin and a little dirt remained on the 

 filter paper. After removing the water, shaking out with alkalies, drying and 

 distilling off the ligroin, there remained 620 grams of the viscous, yellow oil. 

 This was distilled in vacuo, and once redistilled in vac-uo gave 190 grams of an 

 almost colorless oil having the following properties : Boiling point at 10 milli- 



meters' pressure, 120° to 125°; specific gravity, ^,=0.9105 ; X2^ =1..5014; 



'^0° 

 A""" =85.8. 

 D 



This sesquiterpene is only partially soluble in 95 per cent alcohol. It is not 



completely miscible with glacial acetic acid. On adding to this mixture a drop 



of concentrated sulphuric acid, there is obtained a fine, red color, which gradually 



•darkens. 



