Vitamin Stills

The usual chemical method of obtaining vitamins from fish oil is to remove the oil and leave the vitamin--like obtaining a carburetor by removing the rest of an automobile of which it is part. Distilling is a more efficient method of obtaining vitamins from oils, but distilling vitamins is not so simple as distilling whiskey. Vitamin distillation has been practical only in recent years, has not yet been completely commercialized. Last week, at scientific meetings in Ithaca, Manhattan and Washington, Dr. Kenneth Claude Devereux Hickman of Eastman Kodak laboratories, Rochester, N. Y.--a British bachelor of 41 who likes to give gay cocktail parties, and happens to be more responsible than any other chemist for developing the technique of vitamin distillation--described the results which he and his co-workers have obtained in this new field.

If the air in a distilling vessel is pumped out leaving such a high vacuum that practically none is left, molecules flying off a hot distillate have "free paths"--that is, they are not interfered with in their flight. The free paths of molecules differ with their weight. Hence, by adjusting the distance between the hot surface of the distillate and a cold condensing surface, molecules can be separated by weight. "Dr. K. Hickman," said Dr. K. Hickman last week, ''began experiments in high-vacuum distillation in 1927. In 1931 he constructed the continuous molecular still and was able to separate from cod-liver oil a golden waxy concentrate which showed high potency of vitamins A and D. Up to this time, molecular distillation had been a scientific curiosity. It represented the ultimate in the application of vacuum."

In the Hickman still, the hot surface carrying the distillate and the cold condensing surface are in the form of concentric, vertical cylinders. The vacuum is about one-millionth of atmospheric pressure. General Mills joined Eastman Kodak in erecting a pilot plant, which was put into semi-commercial operation a year ago. Its Vitamin A capacity is 60 billion units a week. This output is expected to be trebled by two stills of improved design now under construction.

But the development of new stills resulted not only in a new method of obtaining vitamins, but in the discovery that vitamins previously recognized as individuals were in fact whole tribes of near relations. Distiller Hickman found that as temperature increased, the distillation rate of each vitamin changed and each had its characteristic peak. By this means he established that different fishes manufacture different kinds of Vitamin D. Vitamin D obtained from bluefin tuna did not resemble, in distillation behavior, the vitamin from white sea bass. Cod-liver oil was found to contain two major Vitamin Ds and some minor ones, making at least four and possibly five in all. When the new stills are completed it is hoped that these will be isolated and identified.

Another discovery was a sort of dummy Vitamin A, having a typical vitamin structure but no biological activity. This was labeled "Spurious A." Distilled Vitamin A esters are entirely free of this masquerader. They are also, said Dr. Hickman. "particularly stable to heat or oxidation. They are recommended especially for incorporation into fats and other foods, into chocolate, and into capsules for medicinal use. Distilled A capsules do not cause the unpleasant repeating or aftertaste associated with crude fish oils."

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