SCIENCE AND INDUSTRY. 
Some Australian Essential Oils. 
; By JOHN K. BLOGG. 
In commenting upon the subject of Australian essential oils, it is 
important to consider their value as a commodity for export. Con- 
tributions to the exports from Australia do the State a good service. 
Especially is this true at the present time, when it is so desirable to 
have credits on the foreign market wherewith to meet debits we incur, 
or wish to incur. While the essential oils from Australian indigenous 
products would never at any time run into big figures, if they contribute 
their full quota the sum will not be an insignificant amount. 
The most valuable essential oil that Australia can produce without 
special cultivation is that of the Backhousia citriodora, a native of 
Queensland. This oil is the most prolific of citral of any known variety; 
indeed, it consists almost entirely of citral*. It is practically free from 
terpenes}. itral isthe element of flavour contained in essential oil of 
lemon, though to the extent of only 5 per cent. or, perhaps, a little more; 
yet for the sake of this small quantity of flavouring matter, large quan- 
tities of oil of lemon are produced in Italy and other places. 
It is true that citral is derived from other sources, such, for instance, 
us lemon grass, Cymbopogon citratus and Cymbopogon flexuosus; the 
former from: Ceylon and Straits Settlements, and the latter from 
Malabar. Essential oil of lemon grass yields 70 per cent. to 85 per cent. 
of citral; its chief use is for the manufacture of perfumery, and since 
the discovery of a process for converting it into ionone, it is very 
largely used for that purpose. Ionone possesses an intense odour of 
violets; even a microscopic portion of it will fill a large room with its 
perfume. The demand for ionone under various fancy names has 
increased so enormously that the oil of lemon grass produced is now 
insufficient for the world’s requirements. Manufacturers have had to 
pay constantly increased prices, though the area of the cultivation of 
the plant has been much enlarged. Any other essential oil that would 
yield a high percentage of citral should be able to command a very fair 
return to the distiller. The present price of citral is 35s. per lb. in 
London. In Backhousia citriodora we have an indigenous source of 
citral, with the world waiting for it. Can it be that this source of 
citral is neglected through ignorance of it? The Germans are not 
ignorant of it; and, but for the war, a German firm that had sent a 
scientific observer to spy out Australian products of value, had made 
arrangements to distil this very oil in Australia, and export it to 
Germany. Jonone is a most difficult synthetic perfume to produce. I 
have not heard of any one in Australia, beside myself, who has suc- 
ceeded; failure being probably due to inaccuracies in carrying out the 
routine of the sequent steps toward its production. In manufacturing 
jonone from the essential oil of Backhousia citriodora, at the time of 
writing, I believe my operation to be unique. My first step was to 
extract the pure citral from the essential oil, reserving the terpenes 
and resinoid for future observation. The extraction of the citral may 
~~ s Gildermister and Hoffman. The Volatile Oils 1918. 
+ Ernest J. Parry. The Chemistry of Essential Oils 1908. 
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