Selections. 



[NO. 4, NBW SERIES, 



with tln s addition of a small quantity of oxidizing agent, as chlorine, hypo- 

 chlorite of lime, or bichromate of potash, yields an essential oil of a fine 

 blue, whilst ordinary copaiha containing " to/) resin" (I still scarcely 



understand), affords* hardly any coloured essential oil. The notice con- 

 eludes with pointing out a possible sophistication which appears to me little 

 to be feared ; it is. that eold 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 mix- 

 ture of olive oil or of some other fatty oil, mixed with a small proportion 

 of copaiba. 



Mr. D. II anbury informs us in his notice, that Wood Oil is extracted 

 from Dipterocarpui turbmatw 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 in the trunk of the tree at about 

 30 inches from the ground, mi which a fire is lighted and kept up until 

 the incision is charred : soon after this, the liquid begins to flow. It is 

 conducted by a little trough into a vessel placed to receive it. The aver- 

 age produce of one of the better trees in a single season, is 30 gallons- 

 Roxburgh [from whom this account is taken] adds that Wood Oil is also 

 produced by D'/pfcrncarpus incamts, D. alafus, and D. costalus. The first 

 of these three is reputed to yield the best sort, and in the greatest quan- 

 tity. 



The "Wood Oil which forms the subject of Mr. ITanbury's notice has 

 been imported in large quantity from Moulmein in Burmah : when filter- 

 ed, it is a transparent liquid of a somewhat dark brown when seen by 

 transmitted light, but appearing opaque and of an obscure green if viewed 

 by reflected light. It possesses therefore, in a very marked degree, the 

 dichroism observable in all resin-oils obtained by the action of fire. I 

 particularly notice this character which determines the nature of Wood 

 Oil, and shows that it is not simply a natural product like Copaiba ; but 

 that it is in part the result of a liquid modification of the Dipterocarpus 

 resin, effected by the agency of heat. This Moulmein Wood Oil is of 

 somewhat greater consistence than Olive Oil ; it has a sp. gr. of '964, 

 and possesses an odour and taste very analogous to those of copaiba. It 

 dissolves in twice its weight of absolute alcohol, with the exception of a 

 minute residue which is deposited upon repose. 



But the most curious property of this oil, already recognized by Mr. 

 Lowe, and afresh observed by Mr. Hanbury, is that of solidifying when 

 heated in a closed vial to 266 9 F. ; at this temperature the oil becomes 

 turbid and so gelatinous, that it is not displaced upon the inversion of the 



