This vitalizing element, though analogous to electricity, is not identical with it. We find it absent in a room that has been recently plastered, and is not quite dry. Sleeping in such a room is positively dangerous. We find the same negative depressing condition wherever evaporation has been going on in the absence of sunlight, which appears to supply the needful element. As evaporation carries off this vitalizing element, precipitation or condensation seems to supply it, especially precipitation from the upper regions of the atmosphere to which it is carried by evaporation, and to which it is supplied by sunshine. Hence we experience a delightful freshness of the atmosphere after a summer shower, or on a frosty morning, when the moisture is not only precipitated, but condensed into frost. Frost gives off more of the exhilarating element of watery vapor than dew, because it is a step farther in condensation. Hence there is a healthful, bracing influence in cold climates, where all the moisture is firmly frozen, and a very unpleasant, depressing influence when a thaw begins. The vicinity of melting snow, or a melting iceberg, is unpleasant and promotive of catarrh and pulmonary diseases. The pleasant influence of the fresh shower ceases when the fallen moisture begins to evaporate, and the dewy freshness of the early morn before sunrise ceases as the dew evaporates. The most painfully depressing atmosphere is that which sometimes comes in cold weather from Northern regions which have long been deprived of sunshine. This element of health, which physiologists have neglected to investigate, has recently been sought by Dr. B. W. Richardson of England. The Popular Science News (of Boston) says:-- "Dr. B. W. Richardson of England, in making some investigations upon the physiological effects of breathing pure oxygen by various animals, has discovered, that, by simply passing the gas a few times through the lungs, it becomes "devitalized," or incapable of supporting life, although its chemical composition remains the same, and all carbonic dioxide and other impurities are removed. He also found, that, by passing electric sparks through the gas, it became "revitalized," and regained its usual stimulating effect upon the animal economy. The devitalized oxygen would still support life in cold-blooded animals, and combustible bodies would burn in it as brilliantly as ever. Dr. Richardson considers that, while the gas is in contact with the tissues or blood of a warm-blooded animal, some quality essential to its life-supporting power is lost. The subject is an interesting and important one, and deserves a more thorough investigation."