13 
TIMBER. ESSENTIAL OILS. 
of the wood will be valuable aids to determination when taken in connection with 
other characters of the tree, and should be noted whenever split or sawn specimens 
are available. For the scientific technologist the case is different. He has his 
laboratory and can make tests and comparisons that to the ordinary timber worker 
are impracticable. In his hands a piece of wood may declare the species to which 
the tree from which it was taken belonged. The work already mentioned entitled 
The Hardwoods of Australia and Their Economics by Richard T. Baker of the 
Sydney Technological Museum, 1919, is a splendid record of successful work in 
this department. It is ably written and superbly illustrated with plates showing 
the textures and colours of many Eucalyptus and other woods. 
(/) OILS AND KINOS. 
Eucalyptus trees had not long been discovered before it was realized that their 
leaves were in many cases richly charged with essential oils. In due time enter¬ 
prising chemists set about extracting the oils from the more promising of the 
species then known, and putting them on the market. From these small experi¬ 
mental beginnings a great business has arisen, so that to-day Eucalyptus oils are 
known and valued all over the civilized world. In their constituent hydro-carbons 
these oils differ over a wide range, and can be placed in several distinct groups. 
Messrs. Baker and Smith in their work A Research on the Eucalypts and their 
Essential Oils, 2nd Edition, under the question of evolution of the species, say 
that “The Genus may be considered as embracing four large groups which may be 
indicated, chemically, as follows:— 
Those yielding oils consisting largely of the terpene pinene; either dextro¬ 
rotatory or laevo-rotatory. 
( b ) Those yielding oils containing varying amounts of pinene and cineol, but in 
which phellandrene is absent. 
(c) Those yielding oils in which aromadendral is a characteristic constituent, and 
phellandrene usually absent. 
(d) Those yielding oils in which the terpene phellandrene is a pronounced con¬ 
stituent, with piperitone mostly present.” 
In a later section of the book the authors discuss the commercial applications 
of Eucalyptus oils under the following headings: — 
(a) Pharmaceutical Purposes. — Here it is cineol or eucalyptol that forms the most 
valued constituent. 
(b) Mineral Separation. — The most important agent here is the phellandrene- 
piperitone oil. It is used for the separation of metallic sulphides from the 
gangue by a process of flotation. The process, which is protected, was dis¬ 
covered at Broken Hill, New South Wales, by Mr. Henry Lavers, who is 
quoted as stating that less than a pound of the oil is sufficient to recover the 
values from a ton of ore. 
(c) Perfumery Purposes. — Here the demand is for geraniol, citronellal, piperi¬ 
tone. and aromadendral. 
