Vacuum Distillation

That vitamins A and D can now be produced to sell as cheaply as good brandy is a fact which the chemical engineers of Arthur D. Little, Inc. let out of the pandora box of industry last week. The process simply requires distillation in a vacuum. This is an engineering feat so new that few industrialists know that it exists or what it means. Patents belong to English and Dutch concerns (Imperial Chemical Industries Ltd., Metropolitan-Vickers Electrical Co. Ltd.. Batavian Petroleum Co.). In the U. S., Eastman Kodak Co. is using the method to refine organic mixtures like cod liver oil, which decompose before they boil.

The simple apparatus for vacuum distillation includes a cylinder set squarely within another cylinder like an arm in a sleeve. A heating device keeps the inner cylinder warm. The outer cylinder remains at room temperature or may be cooled. A vacuum pump exhausts air from the space between the two cylinders. When the vacuum has been created, the liquid to be distilled flows down over the surface of the warm inner cylinder. As the liquid flows, molecules of vitamin A or D or other light substances pop off, jump the inter-cylinder gap, condense on the inner wall of the bigger cylinder. Condensed, they dribble down into a container, while the heavier fluid flowing down the inner cylinder runs off into a second pair of evacuated cylinders.

The temperature of the second pair may be higher than that of the first. In that case heavier molecules will be driven from the mother liquid, and a new. distillate is produced. The number of cylinder sets in such a vacuum still may amount to a dozen, but four or five seems to be the most efficient series.

Europeans use vacuum distillation to strip the flavor ingredients and vitamins from butter. Their vitamin concentrates are reported free from all taste, stable and suitable for mixture with foods. They also sublime hormones from urine, soap stock from fish, caffeine from coffee, quinine from cinchona bark.

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