Last week Daedalus proposed a self-supporting Langmuir–Blodgett film. Its long-chain molecules, unlike those of normal films, are at right-angles to its own plane. DREADCO 'Langblofilm' may need its own porous support, but it lets small molecules percolate across it — in effect it is riddled with tiny holes. With an aluminium electrode layer evaporated on each side, and a voltage applied, liquid water molecules are driven across it by electro-osmosis. In this way it will remove water vapour from a room. As a wallpaper, it can pump water into the porous wall, from which it will evaporate and disperse.

Langblofilm is also ideal for removing liquid water from air, which holds it as humidity. Water users, from campers to horticulturalists and even to whole dry states, will welcome it not merely as a dehumidifier, but as a way of being independent of taps, rivers and reservoirs.

But Daedalus wants his film to do more than merely drying air. It would be ideal for removing smell. It could keep any kitchen sweet, replacing activated charcoal, air-fresheners, other domestic absorbants and air conditioners. In a living room it will pump away the human 'fug' of a dense gathering. Carbon dioxide is probably innocent. In spacecraft and nuclear submarines, human beings share a small volume of recycled air. Their sweat and trace emissions give a lot of trouble. The key molecules are probably small with high permittivity, ideal for Langblofilm. Its vast area and silent action should condense them on the wall and pump them outside without anybody even noticing.

DREADCO biochemists are now designing a small Langblofilm unit of higher voltage, to collect human 'fug' and concentrate it for research purposes. The result should be a liquid, mainly water but with the crucial smell molecules dissolved in it. Many social observers have claimed that a particular social scene has the 'wrong smell'. Emotions such as interest, fear and even panic are claimed to have smells of their own, detectable by dogs and other animals.

Non-human assemblies have their own characteristic 'fugs', as visitor to zoos have commented. So the study of fug might reveal a whole new biochemical way of looking at animal species, their emotions, and how these spread. Instinctive human sympathies and antipathies would be clarified, too. And now that military conflict occurs in caves and enclosed spaces, the study could have useful anti-social applications of its own.