842
JOURNAL OP CHEMICAL
EDUCATION
JULY. 1926
obtained by addressing H. V. Church, perennial secretary of the organizationat Cicero. Ill. 0. J. S. Rocq-lead, Ore-lead, and the Age of the Earth. A. H o ~ m s . Nature, 117, 482 (192G).-If all rack-lead ha? been derived from the radio-active elements the time required for the disintegration is approximately 3200 million years. The atomic weight of rock-lead should be a little less than 207. The lead of cornmere, which that ordinary lead cannot have been wholly is ore-lead, is 207.2. It is therefore -in derived from the radio-active elements during their terrestrial history. Since an nnknown amount of the lead in igneous rocks may be ordinary lead i t is clear that the earth as a radio-active container cannot have existed for so long as 3200 million years. This is in accordance with the evidence of radio-active minerals. The greatest age yet determined is that of a pitchblende from the Black Hills, S. D. The analysis indicates an age of 1525 million years and the at. wt. of the lead is 206.07. The frequently quoted figure for the age of the earth, 1600 million years, thus appears to be of the right order. From the point of view of ore-genesis, the distinction drawn between ore-lead and rock-lead is of fundamental importance. H. K. M. Some Properties of the Vitamins. E n ~ T o n r a ~ .Nalurc, 117,5224 (1926).-An exrcllent, concise review of our present knowledge of vitamins. H. K. M. 3. W. McBnm. Theories of Adsorption and the Technic of Its Measurement. Nature, 117, 55Ul (1926).-Most of the published data on the sorption of gases and vapors have no quantitative significance hecause they refer to insufficiently cleaned surfaces. The behavior of a surface when cleaned from the preexisting impurities assumes a different and hixhly significant farm. Examples are given using charmal in the ordinary manner and when the same surface is cleaned. In the Latter case the sorption is greater and practically complete a t comparatively low pressures, remaining constant a t a saturation value as the pressure is further increased. The three competing theories of adsorption-the monomolecular films of Langmnir, the polymolecular films of Polanyi, and the capillary hypothesis of Gurwitsch--are discussed. The experimental results of the present paper afford almost conclusive support for the H. K. M. hypothesis of a monomolecular film. Bigamous Hydrogen-A Protest. H. E. ARMSTRONG. Nature, 117, 5 5 3 4 (192G).-"The bump of judgment seems t o be lacking in the modern school of chemistr- the judicial sense is nowhere to be found. Seemingly any wild-cat speculation may be indulged in upon paper. Surely i t were time that we returned to serious work in the laboratory and that some effort were made to incnlcate the principles of logic H. K. M. into the minds of university students." Mercury Helides. J. J. MANLEY. Nalure, 117, 587-8 (1926).-Manley has improved his technic and is now able to synthesize larger quantities of the mercury helide. His results are described a t greater length than in his earlier papers. He H. K. M. obtains two helides, HgHe,o and HgHe. Argon gives negative results. The Geological Age of the Earth. A. HOLMES. Nature, 117, 5 9 2 4 (192G).I n delivering the Robert Boyle lecture last year Prof. Joly returned to his attack on the higher estimates of geological time which have been based on the l e d r a t i o s of uranium-bearing minerals. He favors an estimate of 16W40 millions of years for the period that has elapsed since the Archaean and refers to the lead-ratios of certain thorium minerals and to the sodium method of arriving a t the age of the oceans as providing confirmatory evidence. Holmes endeavors to show that in both cases the data used are misleading and that the results from both methods can be readily interpreted to support the very estimates to which Prof. Joly considers they are opposed. H. K. M. A Provincial Professor's Profession. G. L. DIPPENBAUGR.Edfcc. Rev., 71, 2 6 6 8 (1926).-A short article that lets those who are dubious see clearly why they H. K. M. are teaching. Concrete Pipes Studied for Resistance to Soil Alkalies. With all the improvements in the use of concrete, no way has yet been found to make it completely resistant to the action of alkali soil. Dalton G. Miller, drainage engineer of the U. S. Bureau of Public Roads told the American Society of Agricultural Engineen recently. Such pipes may be made highly resistant, however, he said, if the greatest care is taken to select the best concrete; hy using a mixture rich in cement and by keeping water containing sulfates away from the pipe for as long as possible, so that i t can get a chance to dry and harden in the air.-Science Snoice
