Eucalyptus oil

First broadcast August 1997.

What would you say was Australia's most significant export of the eighteenth century? Those of you brought up on a diet of school-based worship of John Macarthur might well say that Macarthur's fine merino wool was the first-ever export from Australia. If that was your first choice for an answer, sorry, but you'd be wrong. Merino wool was significant all right, but not until the next century.

Other people might say it was the clay that Governor Phillip sent back to England, the clay that Josiah Wedgwood made into a medallion, so Erasmus Darwin could write poems about it. They'd be closer to the mark with this one, but they'd still be wrong. Right century this time, but that was just a bit of speculation that never led to anything much.

Well, you could probably argue about it till the cows come home, but one of the very first exports, if not the first, from the infant colony in Sydney was a sample of two pints of Eucalyptus oil, sent off to London by Surgeon White, on the same ship as Wedgwood's clay. And that eucalyptus oil was a significant export, because it led to something.

We shouldn't really be surprised that the early settlers tried out local products for anything and everything. After all, they were at the opposite end of the world from ‘Home’, as they saw it, and they needed to be self-reliant in as many things as possible, and as quickly as possible.

It was only a year or two before the First Fleet sailed that James Hutton laid down the basic principles of geology, so that there were few people in the world who understood rocks. Clay, yes, more or less, but rocks were all a bit of a mystery. Early accounts of colonial rocks speak not of Sydney's sandstone, which indicates an origin, but of ‘freestone’, a term that refers simply to the stone's uses.

So, in the absence of any even slightly qualified geologists, the First Fleeters would've been wasting their time looking for minerals. That sterile Sydney sandstone wasn't much of a geological treasure-house in any case, and on top of that, the settlers had a more urgent need for foods and medicines.

They could try the local plant products for these needs, and they set about the task with great enthusiasm. They ate the plants, they boiled them, they drank them, they gargled them, they sniffed them, they rubbed them on their skins, they wore them on their heads . . .

They tried almost everything. Of course, they could have been helped in their enquiries by the local experts on the subject, people who'd sussed out all the best vegies quite a few centuries earlier. But most of the early settlers were too vain, too sure of their civilisation to learn the easy way, so they set out to reinvent the wheel.

To give them their due, though, the early settlers also brought some new methods with them, methods from the days of alchemy, (or was it from the nights of moonshining?), useful tricks for separating liquids. They knew how to distil things.

Now obviously it would be very handy to find out lots of useful things about the most common plants, and the gum tree was generally regarded as the most common plant. So the whites set about with gusto to investigate its useful features.

The early visitors to our shores really were quite convincing about the ubiquity of the gum trees. Charles Darwin, almost fifty years after the colony was founded, commented on how Eucalyptus was the prevailing plant. Mrs Meredith, Charles Sturt, Anthony Trollope, even Dampier, they all said the gum trees were everywhere. The gums depressed them.

Governor Phillip said it too, when he reported in November 1788, on ‘...a tree, of which we have whole forests, from the leaves of which is distilled an essential oil that appears to be the equal to oil of peppermint’.

The first Eucalyptus product the settlers tried was the kino, or exuded sap, from what they called the ‘red gum’. This was probably either Angophora costata or maybe it was Eucalyptus gummifera.

While there was some early interest in the new oil, little happened with it until Joseph Bosisto, a pharmacist, was advised by the German botanist, Ferdinand von Mueller to study the essential oils, the oils that make an essence, if you like. It was Bosisto who first produced commercial quantities of eucalyptus oil in the 1850s.

A Frenchman, Prosper Ramel, soon suggested that the oil should be used as a cure for malaria, but this was only the start of a long run of quackery. Australia, somebody said, was free of the ague. This just had to be due to the presence of Eucalyptus oil in our atmosphere.

And then the reports of miraculous cures came pouring in.

To be kind, this was a time when the germ theory of disease was still to be developed, and most illnesses were blamed on noxious vapours. So it shouldn't surprise us too much to find doctors prescribing less noxious vapours, sweet-smelling vapours, as cures for all manner of things.

Take Mr. Mercer of Kerang. The medical officers of the Bendigo hospital diagnosed him as having cancer of the tongue, and advised him to have the tongue removed. Reading between the lines, it seems that Mr. Mercer was noticeably unmoved by this suggestion, and promptly removed himself from the hospital. Given what happened next, I don't blame him.

Instead of radical surgery, Mercer applied ‘Eucalyptus extract’ to his tongue, and was ‘cured’ of the cancer. I suspect a faulty diagnosis here, as I do in some of the other ‘cures’. How, for example, could we explain the curing of gonorrhoea by injections of gum arabic and eucalyptus extract? The victim's blood might be thicker than water after such a treatment, but cured? I doubt it.

Whatever the cause, eucalyptus oil became a popular disinfectant, a role it maintained as the medical profession began to accept the germ theory of disease. So we find a learned German gentleman explaining that

‘The oil acts highly beneficially on wounds, whether applied directly, or mixed with water and used to irrigate wound cavities. Pure eucalyptus oil is not poisonous in comparison with carbolic acid and can therefore be administered, even in large doses internally.’

Most Australians who've travelled overseas know there are gum trees in many different countries, but this is no new migration. The gum tree was wandering all over the globe quite early in the nineteenth century, to be used for firewood, pit props, shade, or even for reclamation of the desert.

To take a less-known example, Addis Ababa in Ethiopia owes its very existence to the local plantations of gum trees which supplied firewood to the Ethiopians: the city's name means ‘beautiful flower’, and refers to the gum blossom.

Alcatraz gaol is on an island decorated with gum trees: in fact, the Californian forestry authorities sell the seeds of Eucalyptus saligna, our Sydney bluegum, under the name ‘California bluegum’. Our honest local foresters, by the way, have made no equivalent larcenous attempts on the Monterey pine. Maybe they should.

There are even gum trees in Inverness, in Scotland, so if the Loch Ness monster ever gets a sore throat, it'll find a suitable remedy, close at hand.

So widespread are our gum-trees that a few years back, a gynaecologist in Melbourne, Robert Zacharin, wrote a whole book on the topic, complete with pictures of gums in many exotic locations. And yet Dr. Zacharin left out one of the best parts of the story, because his interest lay with the trees, not with the oil.

By the 1890s, more than 7600 litres of the oil were produced in Australia each year, selling at 2/6 a pound. Soon, however, there were foreign competitors who were helped, no doubt by research from the workers at the Technological Museum in Sydney.

One of these researchers is worthy of special note: Joseph Henry Maiden, a dedicated botanist, who even named one of his daughters ‘Acacia’. Maybe the family sat around saying, ‘What'll we call her, what'll we call her?’ until the name Acacia came to them. Who can say? Maiden was, I'm told, also the proprietor of Bosisto's Eucalyptus oil, but that's another story, one that I'll tell some other time.

The essential oils occur in all gum tree species, but the amount you get, and the composition, varies hugely from species to species, and even somewhat between individuals in a species. If the oils were to be exploited effectively, then the best species, the best individuals and the best parts of the tree needed to be identified. So too did the extraction methods.

At the low end, some species yield only 0.02% of their weight as oil, while at the upper end, the yield can be as high as 3 or even 4%. Usually, one gets the oil out by passing steam over the leaves and floating the condensed oil off the condensed steam, but if you have a low yield species, all you will get from this is a sweet-smelling lab, and no oil.

The early settlers tried the red gum out as a cure for dysentery, and it proved highly effective, far more so than the yellow gum that they obtained from the Xanthorrhoea, or grass-tree. So remember if you're caught short in the bush: don't use Xanthorrhoea for diarrhoea.

But to return to the Eucalyptus oil, it's really a mixture of oils. The major component of the oil is called either cajeputol, or eucalyptol, or 1,8 cineole to organic chemists who have defined it as a smallish organic molecule, with two linked rings, and a molecular weight of around 154.

The density of 1,8 cineole is about 0.93, so the oil will float on water. It melts at 1.5o Celsius, and boils at 176.4o Celsius, but, regrettably, it decomposes at that temperature.

Now here's a problem for the chemists. This little fact means that the oil can't be distilled off by simple heating, so steam distillation is needed. When gum leaves are heated by steam, the maximum temperature reached is kept down to around a nice safe 100o Celsius.

Outside Sydney, at Castle Hill, Maiden, together with Baker and Smith, planted large numbers of the best-yielding species. The trees are still there, if you know where to look. I've never counted them, but there could be as many as twenty species in the plantation, since there are that many species used commercially around the world.

Who, though, makes the oil these days? It seems there are large commercial plantations in the Seychelles, Indonesia, Spain, Portugal, South Africa, Guatemala, China, the Congo and Brazil. And also in the USSR, about which I have some more specific knowledge.

The Russians, you see, found a way of getting three high yield crops in four years. First they planted the trees, and left them to grow for two years. Then they lopped the young trees off at ground level, and extracted the oil.

At the end of the third year, the tree has suckered, and these suckers are lopped and treated. The same thing is done again at the end of the fourth year, after which the trees give up the unequal struggle, and have to be replaced with new seedlings.

What a pity we didn't think of that. But more to the point, why have I got such a thing about eucalyptus oil? Well, I've spent much of my working life in an office, pushing paper around. Some years ago, in the interests of self-aggrandisement or spring fever or something, I bought myself two shiney new plastic trays, one for ‘In’, and one for ‘Out’.

My previous ‘In’ and ‘Out’ trays, shabby, battleship grey things made of pressed steel, were added to my mounting collection of pending trays, of which there are now seven. Or maybe it's eight: who's counting?

The character who delivered the mail to my desk each day found great trouble in telling which tray to put stuff in, and which tray to take stuff from. So he took a leaky ball-point pen, and scrawled ‘In’ and ‘Out’ on two sticky labels, one of them misspelt. Then he attached the labels lopsidedly to my nice new trays.

This was the administrative equivalent of a major territorial invasion, but I contained my anguish, and removed the offending labels. I removed the labels, all right, but not the adhesive that they left behind: that was stuck firm to the plastic.

Then somebody older and wiser than I sprang to my aid, advising me to use eucalyptus oil to dissolve the sticky glue. I did, and immediately I was transported back to a childhood of snuffly nights, bedding down with my pyjama lapels liberally sprinkled with eucalyptus oil. And so I started enquiring into the nature of the oil that brought back so many vivid memories.

Eucalyptus oil, it seems, doesn't just disinfect and cure diseases. Not only is it a marvellous solvent for stubborn things like modern aggressive adhesives and chewing gum, it also helps to get precious metals from difficult ores, and it makes good sheep dip, perfumes, soaps, gargles cough drops, all sorts of truly useful things.

I hang my head in shame. You see, some years ago, driven slightly mad by the Hans Heysen school of Australian painting, I penned a small parody that went something like this:

I love a sunburnt country,
I love it more than some;
But I'd like to see painted just one tree
That isn't a bloody gum.

As I say, I hang my head in shame; I take it all back. The gums have won me over, especially the twenty commercial species. Hereafter, I shall walk around saluting the gums. What a pity though, that there isn't just one more commercial species, for then I could give them a twenty one gum salute.


This is one of a set of talks which were originally heard on ABC Radio National in Australia. All of the talks are copyright © Peter Macinnis, blank, but permission will be readily granted on request for educational and most non-profit purposes—I'm not particularly territorial, and on this one in particular, I'm generally delighted to share.

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