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	Issue 14

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Spray cans and the ozone layer
Shortly after World War II, researchers in the United States discovered that two compounds of chlorine, fluorine, and carbon, used since the 1930 s as refrigerants, were also very good at dispensing aerosol sprays from conveniently sized cans. These fluorocarbon gases, commonly referred to by the trade name ‘freon’, made possible the now ubiquitous deodorant and hair-spray aerosol cans, and are also used to eject many other products from their containers. In 1951 another use was found for them — in production of the foam plastics polyurethane and polystyrene.
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The elusive plague rat A little more than 10 years ago, drenching rain broke a 6´-year drought in central Australia. On the Barkly Tableland and surrounding country in the Northern Territory and Queensland, the floods were followed by a plague of rats that continued, at varying intensity, for 3 years. Download Article

How close is the methane alternative? Power your car with methane made from your household wastes. Use methane in your tractor or to supply your lighting, cooking, and heating needs on your farm. Make the gas by putting your crop wastes or animal manure in a digester. The idea has caught on so well that it's now a part of the folklore of the alternative technology. Download Article

Naming our gum trees
Ranging from the stunted mallees of the desert fringe to the giant mountain ash and karri of the moist south-eastern and south-western corners of the continent, Australia's eucalypts come in many forms. As they dominate 95% of our forest area and spread out over much of the remainder of the country, it's hardly surprising that new species are still being found.
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Recovering metals from industrial effluents The use of ion-exchange resins to remove metals from industrial effluents is becoming increasingly important for pollution control. It is applicable at much lower metal concentrations than the more commonly used precipitation and solvent-extraction methods and, unlike those methods, need not add new materials requiring disposal. Download Article

Tracking city air pollution In assessing a city's air pollution problems, it is necessary to know where different winds take the pollutants. Tracing the movements of pollutants is difficult, especially when, like motor vehicle emissions, for example, they come from all parts of the city rather than from a few isolated sources such as particular factories. Download Article

Growing fuel — a future option? What will the world do when it really does run short of oil? At present we can do little more than gaze at the crystal ball. There really are too many imponderables. Will fusion power at last have been harnessed, or will we have lost our inhibitions about uranium? Download Article

A time for desert blooms We all know that the desert blooms after heavy rain. And indeed it does. Ephemeral plants do germinate, flower, seed, and die — but their seed doesn't just remain in the ground ready for the next time favourable conditions prevail. Download Article