Hot Noses

The sense least understood (not counting humor) is the sense of smell. Its subtleties baffle scientists and enrich perfume compounders. Last week Yale's Drs. Lloyd H Beck and Walter R. Miles, after long and thoughtful scratching of their scientific noses, presented the National Academy of Sciences with a brand-new theory. The nose, they said, is not, as commonly believed, a laboratory which identifies odors by chemical analysis. More likely, its smeller is an instrument or measuring infra-red (heat) rays absorbed by odorous vapors.

It has long been known that many gases and vapors transparent to visible light absorb certain wavelengths of infra-red This fact is used industrially in identifying gases; chemists shoot infra-red rays through a vapor and note what wavelengths are absorbed, and how strongly. Why, reasoned Beck & Miles, should the numan nose not do the same?

Body Broadcasts. They collected data on vapors and discovered that all those studied which have odors can absorb certain bands of infra-red with waves between 7 1/2 and 14 microns long. Vapors without odors do not absorb these wave lengths. Since the human body at normal temperature radiates heat waves chiefly m the 7 1/2-14 band, it looked as if the ability to absorb heat waves on the "body's broadcast frequency" is what makes vapors smellable.

But how does the nose do the smelling? The "smell receptors," patches of specialized cells in the upper nose, lie across air passages from tissues which are normally cooler than they are. Therefore the cells radiate heat waves across the air stream. Beck & Miles theorized that when pure air is passing through the nostrils, the cells give no signal; they are getting rid of their heat at the standard rate. But when an odorous vapor is present in the air stream it absorbs certain wavelengths of the heat which the cells are radiating. The cells can feel the change and the stimulus produces a sensation of smell.

Cockroach Teaser. To check the theory Beck & Miles started with cockroaches, which wear their smellers conveniently on their antennae outside their bodies. They put oil of cloves vapor (attractive to cockroaches) behind a gas-tight window of material transparent to infrared. The cockroaches responded to it just about as strongly as if the barrier were not there. When a thin sheet of glass (opaque to infrared) was added to the barrier, the cockroaches showed no more interest in the window than when there was no oil of cloves behind it.

Next, the two Yale researchers tried bees, which have much more complex reactions. The bees acted like the cockroaches, crawling frustrated outside a heat-transparent window with sweet-smelling honey vapor behind it. Apparently both cockroaches and bees could smell vapors at a distance from their antennae. This may explain how certain creatures, such as male moths seeking their females, seem able to detect odors far downwind.

Vapor Blends. Human beings are harder to test. Their smelling apparatus is deeply buried in the upper nasal passages, where it cannot be blocked off from the vapors by heat-transparent barriers. Beck & Miles hope to lick this problem somehow when they get an infra-red spectrometer for studying the wavelength of fragrances.

If they do prove their theory--it needs a lot of checking--they will open a whole new branch of science: smell spectroscopy. It may be possible to mix two vapors which absorb certain wavelengths and get the characteristic odor of a third. Perfume merchants have already heard rumors of the Beck & Miles experiments, and are itching to excite human males & females with artfully blended wavelengths.

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