Nov "I K?:blk, Picric Acid and Grass-tree Gum. 101 



PICRIC ACID AND GRASS-TREE GUM. 

 By R. A. Keble. 

 [Read before the Field Naturalists' Club of Victoria, qth Aug., 1915.^ 

 Anything that connects Australian natural products with tin- 

 war must be a subject of active interest to naturalists. The 

 scientific committee recently formed in England, with repre- 

 sentatives in every part of the Empire, brings home to us the 

 stern reality that this is a scientific war ; tbat everything 

 relating to the problems awaiting solution has to be passed 

 through the melting-pot of criticism and investigated, lest 

 something of vital consequence may have been missed or dis- 

 regarded in the commonplace of routine. 



A commodity that has been the object of no little inquiry 

 is picric acid. At one time essentially a dye, its output and 

 value were almost entirely regulated by the demands of the 

 dye industry. Its adoption by the French as a basis of 

 melenite (Eugene Turpin). and at a later date by Great Britain, 

 Germany. Austria, Italy, Spain, and other nations as lyddite, 

 ecrasite, thorite, &c, &c, has enhanced its importance. 



Picric acid — trinitrophenol. C 6 H 2 (N0 2 ) 3 OH. is the 

 final product of the action of nitric acid on a large number of 

 substances containing a benzene nucleus. It was formerly 

 prepared by the direct action of nitric acid on phenol, but it 

 is now made by dissolving the phenol in strong sulphuric acid 

 and then acting on the resulting phenol-sulphonic acid with 

 excess of nitric acid. Picric acid separates from the acid 

 mixture as an oily liquid, which solidifies on cooling. It is 

 purified by recrystallization from water.* This process is 

 carried out on a large scale in the coal-tar dye industry, from 

 whence comes the bulk of our supplies.* It is. however, also 

 obtainable from indigo, aloes, and gum resins, and it is the 

 last-named source that has occasioned these and other inquiries. 



The resin of the liliaceous tree, Xanthorrhcea, lias long been 

 known as acaroid resin — a yellow, fragrant, organic compound, 

 soluble in alcohol, ether, and caustic potash. The potash 

 solution, heated with HC1. deposits benzoic acid and cinnamic 

 acid ; nitric acid oxidizes it to picric acid : it yields, on 

 distillation, small quantities ol benzene and styrene, and by 

 potash fusion it gives />. oxy-benzoic acid, resorcin, and pyro- 

 catechin.t In a note on the genus Xanthorrhcea, Baron 

 von Mueller. % writing on X. Tatei, states that the resin " is in 

 demand for incense, for particular sorts of varnishes, for the 

 manufacture of sealing wax .... and for picric acid. 



* See Appendix, No. 1, p. 573. 



t See Appendix, No. 2. 



J Sic Appendix, No. 3, p. 580. 



