VOL.4, No. 7
IONIZATION AND ATOMIC STRUCTURE THEORY
871
Neither can the strictly planetary systems of the physicists be defended successfully in view of the fixed nature of chemical unions in organic compounds. Yet the orbital motion of electrons is generally agreed upon. As Lewis pointed out, we may consider the position of the orbit of the electron as the position of the electron itself, in which case the deductions from the static atom may apply, provided that the electrons do not have the nucleus as the center of the orbit. Physicists seem willing to admit in view of known facts that the valence electrons at any rate have more or less fixed orbits with centers outside the nucleus. The more strictly planetary system may hold for the electrons of the kernel. The position of the present theory of atomic structure is thus fairly secure even though subject to modification. All texts on general chem- . istry make use of the theory and there is agreement on all essential points. The applications of this theory to the field of organic chemistry are no less fundamental and far reaching than the applications to inorganic chemistry, and it would be unfortunate if organic chemists failed to make use of this important contribution. No One Knows W h y Cod Livers Have Vitamins. Chemists are trying to fmd out where codiish get the vitamins that made wd-liver oil famous. Exposure t o ultra-violet rays, which has been shown in the case of cows to increase the vitamin D wntent in dairy products, does not work with fish, declares Charles E. Bills, research chemist of Evansville, Ind., in a report that will appear in a forthcoming issue of the Journal of Biological Chemistry. Fish subjected to five-minute exposures of ultra-violet irradiation every other day for six weeks produced oil that displayed no more potency than that made from fish which had not been so treated. During the period in which the Newfoundland codiishfattens, it gorges itself on small fish known as c a ~ which h contain onlv a small amount of vitamin D. To acwunt for the unusually high potency of cod-liver oil the cod would have to consume, within aperiod i ~ hof t caplin, a most unlikely quantity. of four weeks. about 26 times its w e. The presence of vitamin D in the liver of fish consequently is judged to be the rrsult of chemical reactions in the body of the fish a t present not clearly understood.-Science Service Shows How Roots Get Air to Breathe. Plant roots no less than plant leaves need to breathe, and the rate a t which oxygen can move through the soil is a highly important thing for scientific farming to know, according to Dr. Lee M. Hutchins of the U. S. Department of Agriculture. Before the meeting of the First International C o n p s s of Soil Sciences a t Washington, Dr. Hutchins demonstrated the operation of an apparatus which he devised to measure the oxygen-supplyingpower of the soil. The essential part of the apparatus is a hollow vessel of porous porcelain, buried in the soil to be studied. Pure nitrogen is passed through it, and the outgoing stream is bubbled through a chemical solution that changes color if there is any oxygen present. Theshade of the solution after a given time indicates the amount of oxygen that has passed from the soil through the walls of the porcelain Vessel and into the nitrogen stream. Dr. Hutchins has been using his invention to study the oxygen needs of such typical mops as corn and wheat, and also such plants as rice and willow trees, which can grow in soils that are waterlogged and hence very low in oxygen.-Science Service
