526 



SCIENCE 



[N. S. Vol. XXVIII. No. 720 



Several important papers on fungi appear 

 in the Twenty-first Annual Report of the Ne- 

 braska Experiment Station, viz., " Some 

 Tomato Fruit-rots during 1907," by Miss V. 

 W. Pool, with ten plates ; " A New Form of 

 Sphaeropsis on Apples," by Miss L. B. Walker, 

 with ten text illustrations ; " Seed Treatment 

 for the Smuts of Winter Barley," by Dr. F. 

 D. Heald, with four text illustrations ; " The 

 Mold of Maple Syrup," by Dr. F. D. Heald 

 and Miss V. W. Pool, with seven text illustra- 

 tions ; " A Rot of Grapes due to Pesialozzia 

 uvicola" by F. A. Wolf, with one plate. 



An excellent popular description of the 

 " Smuts of Sorghum " by Dr. E. M. Freeman 

 and H. J. C. TJmberger is published by the 

 United States Department of Agriculture as 

 Circular No. 8, of the Bureau of Plant In- 

 dustry. 



Charles E. Besset 



The Untveesitt of Nebbaska 



GEOLOGY AND RADIOACTIVE SUB8TANGES 

 A PAPER of uncommon interest, particularly 

 to geology and geophysics, has just appeared 

 as a Bulletin of the Geological Society of 

 America (vol. 19, pp. 113-146). The author. 

 Dr. George F. Becker, of the IJ. S. Geological 

 Survey, has brought together the physical 

 data upon radioactive substances, reviewed 

 them carefully for the information of any to 

 whom they are not familiar, ajid then dis- 

 cussed their bearing on the solution of some 

 of the great questions of terrestrial and cos- 

 mogonic history. 



Assuming that the relation now established 

 between helium, radium and uranium points 

 to the common origin of the chemical ele- 

 ments. Dr. Becker calls attention to the fact 

 that only helium, hydrogen and nebulium 

 have been identified in the nebulae, and that 

 an orderly progression can be noticed in the 

 atomic weight of the identifiable elements 

 found in the stars. " Helium stars pass by 

 the finest gradations into hydrogen stars of 

 the Sirian type and these again into Solar 

 stars " which contain elements of atomic 

 weight as high as barium (137.4). The 

 spectroscope has never indicated the presence 

 of uranium in any celestial body, in the sun. 



or in meteoric matter, although helium is 

 widely distributed. Furthermore, the ura- 

 nium and thorium minerals on the earth are 

 confined to the pegmatitic facies of the 

 granites and syenites. There is, therefore, 

 abundant incentive for a comprehensive in- 

 vestigation of a direct evolution of the ele- 

 ments from lowest to highest atomic weight, 

 and the progress of this evolution wiU bear 

 the closest relation to the evolution of our 

 present earth. 



Dr. Becker does not believe that inferences 

 as to the age of the earth are competently 

 drawn from the ratio of uranium to helium 

 or to lead in particular minerals (Rutherford, 

 Boltwood). Neither does the assembled phys- 

 ical evidence indicate that the high tempera- 

 ture of the interior of the earth is due in 

 any considerable part to radioactivity (Dut- 

 ton), though perhaps one tenth of the surface 

 temperature gradient may be of such origin. 

 This would accord with the determinations of 

 the earth's age — not far from sixty million 

 years — made by methods independent of the 

 surface temperature-gradient, including his 

 own discussion of a cooling globe printed in 

 Science last February. There are definite 

 limits of depth below which radioactive matter 

 can not be expected and there is a conspicuous 

 absence of uniformity in its distribution, the 

 concentration in the ocean beds being par- 

 ticularly important. 



Dr. Becker closes with a new and ingenious 

 theory of the formation of granite which 

 undertakes to account for the enormous 

 energy content of the radioactive group of 

 minerals. Supposing the earth to have some- 

 time presented a surface of rhyolitic or 

 trachjiiie magma, it may be supposed to have 

 solidified under stable conditions at about 

 1,300°, surrounded by its atmosphere of water 

 vapor far above the critical temperature of 

 water. It is now assumed that granite must 

 have formed by the surface action of water 

 vapor (aqueo-igneous fusion) upon the rhyo- 

 litic or traehytic mass and that the tempera- 

 ture must have fallen below 800° for the 

 stable formation of quartz. In the interval 

 there must have been opportunity for a tre- 

 mendous potentialization of energy near the 



