What has been said regarding the effect of heat and oxidation on vitamine A may now be repeated with respect to vitamine C (and probably with respect to vitamine B, though not so much work has been done with this one). The impression that vitamine C is the least stable of the three has foundation in the experience of most investigators, but a number of workers have recently shown that it is not so much the heat to which the "C" is subjected, but rather the extent of oxidation, that determines the stability of this vitamine. We now know that both dry and condensed milk, for example, may contain appreciable quantities of vitamine C, provided the method of preparation is such as to protect the milk against oxidation.

Dr. Hess writes: "If, in the course of drying, milk is subjected to oxygenation, as it is in the spraying process, it loses much or most of its antiscorbutic vitamine (vitamine C), whereas if it is dried on a drum and its particles not subjected to air, it is found to contain the greater part of this vitamine. Condensed milk contains considerable of this factor, owing to the fact that the condensation process is conducted with very little access of air. This new conception of the role of oxidation harmonizes many views which heretofore appeared discordant. It explains how the French physicians were probably quite correct when they reported encountering practically no scurvy in the course of feeding sterilized milk to babies; we had paid no attention to the fact that the milk which they fed had been heated in and kept in hermetically sealed bottles" (to which the oxygen of the air could not have access, and hence little or no oxidation could take place).

Another interesting fact that has lately been brought out is the greater stability of this vitamine in acid than in alkaline medium. The acids found in oranges, lemons and tomatoes, for example, are therefore highly desirable adjuncts not necessarily in themselves, but in the property they possess of preventing the rapid inactivation of vitamine C. {References: A. F. Hess, Journal of Industrial and Engineering Chemistry, volume 13, page 1115, 1921; A. F. Hess, Journal of the American Medical Association, volume 76, page 693, 1921; A. F. Hess, Journal of Biological Chemistry, volume 38, page 293, 1921; A. F. Hess, Proceedings of the Society for Experimental Biology and Medicine, volume 18, page 143, 1921; E. A. Duteher, H. M. Harshaw and J. S. Hall, Journal of Biological Chemistry, volume 47, page 483, 1921; S. S. Zilva, Lancet, volume 1, page 471, 1921.)