The Psychology of Scent

Smell is the most mysterious of human senses. Odor engineers need not only chemistry and physics but must also know something about history, psychology and sociology. This is the conclusion of a new book, Odors: Physiology and Control

(McGraw Hill; $6.50), by Carey P. McCord, of Detroit's Industrial Health Conservancy Laboratories, and William N. Witheridge, ventilation engineer for General Motors.

The pleasantness or unpleasantness of an odor is mostly a matter of psychological conditioning. McCord and Witheridge point out that workers in horribly smelly places (such as glue factories) eat hearty meals while surrounded by putrefying carrion, but visitors in such surroundings get sick at the thought of eating anything. People whose minds are fully occupied are often unconscious of odors. "It may be doubted," observe McCord and Witheridge, "that the handful of men and women on Noah's Ark, with their own existence threatened, complained of animal odors about the place." But less preoccupied people than the Noah family make a major to-do about minor stenches.

Resin & Rotten Eggs. Fashions in odor change with the times. In the 17th Century, say the authors, the best-loved perfumes were spices, resins and incense-like aromatics. They suspect that a lovely court lady, deliciously spiced for her time, might be rushed to the nearest exit by moderns. They also suggest that expensive modern perfumes (containing synthetics and animal sex lures) might have caused a similar reaction at the court of Louis XIV.

Fashions in smell vary with geography, too. The authors point out that Chinese gourmets, rebuked for liking "rotten eggs," can point with horror to the "rotten milk" (cheese) that Westerners find so delicious. "The shade of offense from odors," the authors note, "is measured by time, place, occasion and inurement."

Odor In Pairs. Bad smells have affected the futures of big business, and the authors give most of their book to methods of sweetening people, homes, theaters, industrial products and the air around odoriferous factories. It is crude, they think, to conceal a bad smell by a stronger, pleasanter odor. A more efficient method is to get rid of the bad smell itself. This can often be done by washing it out of the air with water or absorbing it in activated carbon.

A subtle and much-used trick is to neutralize an unpleasant odor. How this works is uncertain, but odor engineers have found many "odor pairs," i.e., smells that cancel each other. The smell of cedarwood, for instance, cancels the smell of rubber. Many offensive-smelling commodities are marketed at present with their natural odors neutralized by an odor antagonist.

Having made a specialty of the subject, the authors have acquired a certain affection for bad smells. They tell with considerable sympathy how smelly chemicals often save human lives. For example, when a mine has an accident, the operators often dump ethyl mercaptan (which smells like rotting cabbage, garlic, onions and sewer gas) into its air supply. The awful stench circulates quickly through every passage and forcefully warns the miners to run for their lives.

This file is automatically generated by a robot program, so reader's discretion is required.