478 Transactions. — Chemistry and Physics. 



little doubt that the so-called diterpene obtained by Lieber- 

 rnann* and by Hallerf by the action of hydriodic acid on 

 abietic acid is dihydro-abietene. 



The results obtained by the vacuum distillation led to 

 the belief that similar results would be obtained by the dis- 

 tillation of colophony with superheated steam. A patent for 

 the purification of colophony by this process was taken out by 

 Hunt and Pochin in 1858 ; but no account has been published 

 of the chemistry of the process, if, indeed, it has ever been the 

 subject of investigation. 



Experiments on the steam distillation of rosin were there- 

 fore carried out at Kaiwarra by the kind permission of the 

 directors of the New Zealand Candle Company. The results 

 were completely as anticipated, water-white rosin, heavy 

 hydrocarbon, and a small quantity of pitch being practically 

 the only substances produced by the process. 



Experimental. 

 Preliminary Experiment. 



105 grms. of rosin (N quality) was distilled under di- 

 minished pressure (18 mm. approximately). The course of 

 distillation was as follows : Up to 270° C, 23 grms. ; 270-285° 

 C, 67 grms. ; pitch, 12 grms. ; loss, 3 grms. 



The portion distilling at 270-285° was refractionated. 

 About 70 per cent, of it passed over between 262-268° C. as a 

 light-yellow oil, which when rapidly cooled set to a hard 

 transparent resin ; but which when cooled slowly became 

 opaque, owing to the formation of crystals, which gradually 

 increased in quantity until the whole mass was crystalline. 



This substance was analysed, and gave numbers agreeing 

 closely for those required for abietic acid, but not for those 

 required by the " isosylvic anhydride " of BischofT and Nast- 

 vogel. m 



n , , , ■, c »u- l- Calculated for Isosjdvic 



Calculated for Abietic -p A A , •, ■.-, J 



, -j r* tt rs Found. Anhydride — 

 Acid— Ci9H 28 2 . p tt n 



C = 79-16 78-88 78-86 81-9 



H = 9-72 9-77 9-80 9-9 



Confirmatory Experiment. 



As it appeared possible that the difference between these 

 results and those recorded by Bischoff and Nastvogel might 

 be due to the fact that their distillations were carried out 

 under higher pressure, and that their distillates were more fre- 

 quently fractionated, a fresh set of experiments was made. 



* Berichte, 17, 18841. 

 t Berichte, 18, 2165. 



