226 



SCIENCE. 



[N. S. Vol. IX. No. 215. 



of penetrating ordinary media to a mucli higher 

 degree than the usual X-rays, and that in at- 

 tempting to traverse substances having high 

 atomic weights, lilce uranium and thorium, a 

 portion of the incident energy is transformed 

 into radiation having the power of affecting 

 photographic plates, ionizing gases, etc. Elster 

 and Geitel have tested this by examining the 

 intensity of the uranium radiation by both the 

 electrical and photographic methods, the ap- 

 paratus being placed first upon the surface of 

 the earth and then several hundred meters 

 underground in a mine, their idea being that 

 the intensity of the radiation incident upon the 

 uranium would be weakened by passing through 

 the overlying mass of earth. No difference was 

 found in the intensity of the uranium radiations 

 under the two conditions. 



To test the hypothesis of Crookes as to the 

 radiation being caused by a transformation by 

 the uranium of a portion of the kinetic energy 

 of the molecules of air, the intensity of the 

 radiation emitted by the uranium when in a 

 vacuum was compared with that emitted when 

 the metal was in the air. No difference was 

 found. 



The results of this work are hence unfavorable 

 to either hypothesis. 



M. and Mme. Curie have shown {Comptes 

 Mendus, CXXVII., p. 175) that in pitchblende 

 there is a substance similar in properties to bis- 

 muth, but which is strongly radio-active, and 

 for it they have proposed the name Polonium. 

 In Comptes Eendus, CXXVII., p. 1255, they give 

 an account of their more recent researches in 

 which they have been associated with M. G. 

 B6mont upon this subject. They are led to the 

 conclusion that there is still another new sub- 

 stance present, similar in properties to pure 

 barium, but whose chloride is about nine hun- 

 dred times as active as that of uranium. The 

 new substance, provisionally called Radium, is 

 distinguished by a hitherto unknown line in its 

 spectrum. A.. St.C. D. 



BOTANICAL NOTES. 



SARGENT'S BILVA OF NORTH AMERICA. 



The appearance of Volume XII. of this mag- 

 nificent work again directs attention to what 



will, for all time, be a monument to both author 

 and publishers. Eight years ago the first volume 

 appeared, and at more or less regular intervals 

 the succeeding volumes, until the present one, 

 which was originally designed to be the last. In 

 these volumes we have 620 plates, thus more 

 than making good the promise of author and 

 publishers of fifty plates per volume. We have 

 now the pleasant announcement by the pub- 

 lishers that, " as it has been found impracticable 

 to include in this twelfth volume of Professor 

 Sargent's great work the general index to the 

 entire work, a thirteenth volume containing this 

 index, together with descriptions and illustra- 

 tions of recently discovered species, and such 

 corrections of the original volumes as recent 

 explorations have made necessary will be sent to 

 subscribers without change as soon as ready." 

 The present volume includes descriptions and 

 plates of Larix (3 species), Picea (7 species), 

 Tsuga (4 species), Pseudotsuga (2 species) and 

 Abies (10 species). We shall look with great 

 interest for the appearance of the supplementary 

 volume. 



COMMENDABLE FREE-SEED DISTRIBUTION. 



At last the United States Department of 

 Agriculture has made a free distribution of 

 seeds, which must commend itself to every sci- 

 entific botanist or horticulturist in the country. 

 We refer to the distribution to colleges of the 

 sets of ' Economic Seeds,' prepared in the Seed 

 Laboratory of the Division of Botany, by the 

 lamented Gilbert H. Hicks, under the direction 

 of Frederick V. Coville. The set as issued 

 consists of five centuries, each enclosed in a 

 shallow tray-like box, which is divided into 

 rectangular spaces, each large enough to con- 

 tain the seed-tubes. Each tube is numbered 

 and labeled, and on the lid of the tray is an al- 

 phabetical list of all the species arranged under 

 their appropriate families. It is a pleasure to 

 note, moreover, that the most scrupulous care 

 has been taken to secure accuracy in the no- 

 menclature, which is of the strictly modern 

 school, including double citation of authors and 

 the uniform decapitalization of specific names. 

 This distribution is a worthy and commendable 

 labor of the National Department of Agricul- 

 ture, and it reflects great credit upon the officers 



