Much Ado About Nothing

New applications of high vacuum are making industrial history.

They have already:

> Dehydrated meat at low temperatures so that it keeps all its vitamins and flavor (which previous dehydrating methods failed to do).

> Promised speedy production of penicillin by dehydrating it much faster than it has ever been done before.

> Resulted in a coating for glass lenses that greatly increases visibility (by reducing light reflection). In a submarine periscope, for example, it improves vision up to 200%.

> Made possible the direct reduction of magnesium ore to pure magnesium, without the complicated chemical treatment and great electric power required by other processes.

So promising is the use of high vacuum in magnesium production that WPB officials call the development one of the outstanding technical achievements of the war. Several big magnesium plants, including Henry Ford's River Rouge, have already adopted it. And the major penicillin makers are now using high-vacuum dehydration.

Empty Heads. The new methods were parented by a four-year-old Boston research firm headed by a lanky, sharp-chinned, young M.I.T. graduate, Richard Morse. His researchers call themselves "specialists in nothing." They were not the first to work in their rarefied field, for high-vacuum apparatus is an old tool in the laboratory and in small-scale manufacturing. But Morse's National Research Corp. developed machinery which for the first time makes it possible to use a high vacuum in large-scale mass production.

The basis of a vacuum's industrial usefulness is that it makes it easier to change a solid or liquid into a gas. Under normal atmospheric pressure (760 mm.), the pressure of air molecules prevents or retards the evaporation of molecules from liquids or solids. Evaporation may be speeded by 1) heating, which makes molecules move faster (as in boiling water), or 2) reducing air pressure. Heating, however, may change the chemical make-up of a substance (e.g., heated food often loses vitamins, heated magnesium oxidizes). Industrially, the ideal method would be to evaporate a substance while it is frozen or relatively inactive.

Larger Pumps. That is exactly what Morse's group did, by reducing air pressure to a rarity hitherto unattainable on an industrial scale. To do this, they had to maintain a high vacuum of less than 1 mm. air pressure inside the huge tanks and pipes where materials were to be treated. Mechanical pumps (which work not by sucking but by sweeping air out of a vessel) are not very effective at pressures below 5 mm.

Morse's group solved this problem by making large, high-powered versions of a diffusion pump invented by General Electric's Physicist Irving Langmuir. The diffusion pump works by blowing a strong jet of mercury or oil vapor into the neck of the vessel to be emptied. The vapor stream traps air molecules and sweeps them out through a series of locks. With this equipment, Morse got down to a working vacuum of one micron (a thousandth of a millimeter).

A vacuum of this order makes it possible to handle many materials in new ways. In extracting magnesium, for instance, the ore dolomite (a limestone) is mixed with ferrosilicon and can be successfully heated under high vacuum. The magnesium in the ore does not oxidize, because there is virtually no oxygen present, but vaporizes and is collected on water-cooled condensers.

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