APRIL — sept. 1858. J Properties of Wood Oil. 



117 



Copaiba, rendered turbid by a greenish resin suspended in it. The 

 following were the results obtained by him from the balsam which 

 was found by. filtering to give a brown transparent liquid yielding 

 by distillation. 



Essential Oil 65 



(Hard) Resin 34 



Acetic Acid and Water 1 



100 



According to Mr. Lowe, the volatile oil possesses all the cha- 

 racters of that of copaiba ; and the " hard resin," which he re- 

 gards as pure copaivic acid, free from the " soft resin," which, 

 according to him, exists in the greater part of the copaiba of com - 

 merce, appears to him indicative of superiority as a medicine. I 

 must acknowledge that I but ill-comprehend this conclusion, and 

 that I am the less convinced of the identity of the hard resin with 

 copaivic acid, since Mr. Lowe has recognized in the new resinous 

 balsam the singular property of becoming solid when exposed in a 

 closed vessel, to a temperature of 230° Fah. Copaiba presents no 

 similar phenomenon. 



I find stated moreover this difference, viz., that the new balsam 

 distilled with the addition of a small quantity of an oxidizing 

 agent, as chlorine, hypo-chlorite of lime, or bichromate of potash, 

 yields an essential oil of a fine blue, whilst ordinary copaiba con- 

 taining " soft resin" (I still can scarcely understand), affords 

 hardly any coloured essential oil. The notice concludes with 

 pointing out a possible sophistication which appears to me little 

 to be feared; it is, that cold sulphuric acid produces with copaiba 

 a purple colouration similar to that obtained with cod-liver oil, so 

 that, as the author supposes, dishonest persons might substitute 

 for the latter, a mixture of olive oil or of some other fatty oil, 

 mixed with a small proportion of copaiba. 



Mr. D. Hanbury^ informs us in his notice, that wood-oil is ex- 

 tracted from Dipterocarpus turbinatus by a very peculiar process, 

 which I will state in a few words, in order the better to show the 

 nature of the product. To obtain the oil, a large incision is made 



* Pharm. Jour. Vol. xv. 321. 



