WOOD OIL GURJUN BALSAM. 119 



trees appear sickly the following season, one or more years' re- 1356> 

 spite is given them." 



The same author also states that Wood Oil is afforded by D. 

 costatus (D. angustifolius, W. et A.), D. alatus, Koxb., and D. 

 incanus, Koxb., the last mentioned being reputed to furnish the 

 largest proportion of the best sort. 



Closely allied to the Wood Oil of Dipterocarpus is the oleo- 

 resin termed Camphor Oil, produced by Dryolalanops Camphora, Camphor Oil. 

 Colebr., a tree of the same natural order. For a specimen of 

 this oleo-resin and of an analogous liquid called Lagam Oil, 

 both brought from Sumatra by Dr. Junghuhn, I am indebted to 

 the courtesy of Dr. J. E. De Vrij, of Eotterdam. 



Wood Oil, as imported from Moulmein, is, after filtration, a Characteria- 

 transparent, dark-brown liquid, of somewhat greater consistence t] !S oi i 

 than Olive Oil, a sp. gr. of '964, and an odour and taste like 

 copaiba, though perhaps hardly so strong. One part of it 

 treated with two parts of alcohol, sp. gr. *796, is dissolved with 

 the exception of a minute quantity of darkish flocculent matter, 

 which subsides upon repose. 



But its most curious property (as noticed by Mr. Charles Lowe 

 with reference to a liquid which I suppose to have been Wood 

 Oil 1 ) is that exhibited when it is heated in a corked vial to about 

 266 F. (130 C.). Thus treated it becomes slightly turbid, and so 

 gelatinous that the vial may be inverted, even while hot, without 

 its contents being displaced ; and on cooling, the solidification Solidification. 

 is still more complete. Gentle warmth and agitation restore to 

 a great extent its fluidity, but solidification is again produced 

 upon the liquid being heated to 266 . 2 Copaiba displays no such 

 phenomenon. 



According to Dr. O'Shaughnessy, when Wood Oil is heated 

 in a retort, a yellowish white, crystallizaUe, solid substance 

 having many of the properties of benzoic acid sublimes into the 

 upper part of the vessel, to the extent of about one per cent, of 



1 On a new variety of Balsam of Copaiba, Pharmaceutical Journal, vol. 

 xiy. pp. 65, 66. 



2 Mr. Lowe says 230 F., but a much more striking effect is produced on 

 the Wood Oil by the temperature I have named. 



