l62 



NA TURE 



[June i6, 1904 



known to exist in the atmosphere, the active matter of 

 slow dissipation produced from the emanation must be de- 

 posited on the surface of all bodies exposed to the open air. 

 The radio-activity observed in ordinary materials is thus 

 probably, in part, due to a thin surface film of radio-active 

 matter deposited from the atmosphere. 



A review is given of methods of calculation of the magni- 

 tude of the changes occurring in the radio-elements. It is 

 shown that the amount of energy liberated in each radio- 

 active change, which is accompanied by the emission of 

 a particles, is about 100,000 times as great as the energy 

 liberated by the union of hydrogen and oxygen to form an 

 equal weight of water. This energy is, for the most part, 

 carried off in the form of kinetic energy by the a particles. 



h description is given of some experiments to see if the 

 o ravs carried a positive charge of electricity, with the view 

 of determining experimentally the number of a. particles 

 projected from one gram of radium per second. Not the 

 slightest evidence was obtained that the a rays carried a 

 charge at all, although it should readily have been detected. 

 Since there is no doubt that the a rays are deflected in 

 magnetic and electric fields as if they carried a positive 

 charge, it seems probable that the a particles must in some 

 way gain a positive charge after their expulsion from the 

 atom. 



Since, on the disintegration theory, the average life of 

 a given quantity of radium cannot be more than a few 

 thousand years, it is necessary to suppose that radium is 

 being continuously produced in the earth. The simplest 

 hypothesis to make is that radium is a disintegration pro- 

 duct of the slowlv changing elements uranium, thorium, or 

 actinium present in pitchblende. It was arranged that Mr. 

 Soddy should examine whether radium is produced from 

 uranium, but the results so far obtained have been negative. 



I have taken solutions of thorium nitrate and the " eman- 

 ating substance " of Giesel (probably identical with the 

 actinium of Debierne) freed from radium by chemical treat- 

 ment, and placed them in closed vessels. The amount of 

 radium present is experimentally determined by drawing 

 off the emanation at regular intervals into an electroscope. 

 A sufficient interval of time has not yet elapsed to settle 

 with certainty whether radium is being produced or not, 

 but the indications so far obtained are of a promising 

 character. 



RECENT PUBLICATIONS IN AGRICULTURAL 

 SCIENCES 



'X'HE United States Department of Agriculture has issued 

 the fourth annual instalment of the great work upon 

 which its Division of Soils has embarked, the detailed survey 

 of the soils of the whole of the country. The area covered 

 by the present report is little less than 18,000 square miles, 

 which have been surveyed at a total cost of 12s. per square 

 mile. The work is being carried on simultaneously in many 

 parts of the States ; the counties dealt with embrace some 

 of the old settled eastern States like New York and New 

 Jersey, the Carolinas and Virginia, the rich lands of Ohio, 

 Kentucky and Illinois, also the recently settled districts in the 

 Dakotas, Texas, Colorado and other areas of deficient rain- 

 fall, the Walla Walla wheat area on the Pacific slope, and 

 the lately acquired dependency of Porto Rico. 



The method adopted follows that of the earlier reports ; 

 a field party maps the distribution of the soils in each section 

 and collects information as to the crops grown and their 

 average yields, the conditions of labour and transportation, 

 at the same time indicating the suitability of the land for 

 new crops and systems of farming. Mechanical analyses of 

 each type of soil are made at Washington and are set out 

 in the report ; occasionally chemical analyses are included ; 

 statistics of rainfall and mean temperature are also added. 



The whole work is based upon the facts that different 

 types of soil can be recognised and the areas which they 



A " Field Operations of the Division of Soils^ iqoz." By Milton Whitney. 

 Pp. S42 ; with a case of maps. (Washington : U.S. Depaitment cf Agri- 

 culture, 1903.) 



" Monograpbie Agricole du Pas-de.Calais." By M. Tribordeau. 

 Pp. 296. (Paris ; Socicte' d'Encouragement pour I'lndustrie Nalionale, 

 1904.) 



" The Journal of the Royal Agricultural Society of England," vol. Ixiv. 

 Pp. 420+clxx.vviii. (London : John Murray, 1903.) 



NO. 1807, VOL. 70] 



occupy can -be approximately mapped, and that particular 

 crops and systems of farming can be associated with the 

 various soil types, so that the agriculture of each area can 

 be directed along the most appropriate lines and its farmers 

 saved from many unprofitable experiments. While the- 

 volume contains no striking novelty, it is full of interest 

 and instruction to the English student of agriculture or 

 economics. 



M. Tribordeau gives an account of the agricultural con- 

 dition of the Pas-de-Calais, dividing it into regions based 

 upon geological considerations of the nature of the sub- 

 soil. A description of each soil is given, generally accom- 

 panied by several analyses by M. Pagnoul ; then follovi's an 

 account of the agriculture, with reports in considerable- 

 detail of the system pursued on one or more farms of different 

 sizes in the area. The varieties of each crop generally 

 grown, the races of live stock, the yield, the conditions of 

 labour, even the implements in use on each farm are care- 

 fully set out. The latter half of the volurne deals more 

 generally with the agricultural economics of the district, and 

 discusses the position both financial and moral of the- 

 labouring class, the conditions of tenure, the societies and' 

 other means adopted for the encouragement of agriculture, 

 particularly the spread of the movement for credit banks and 

 cooperative associations. The work is liberally illustrated! 

 with maps, photographs and diagrams, and presents a 

 valuable picture of the present critical condition of agri- 

 culture in western Europe. 



The current volume of the Journal of the Royal Agri- 

 cultural Society, which now appears annually only, is some- 

 what more exclusively occupied than usual with the work 

 of the society. In addition to the usual prize lists there is. 

 a general account of the show held at Park Royal last June, 

 another article on the machinery exhibited there, and a full' 

 discussion of the trials of wind pumping engines conducted' 

 by the society in 1903. Reports of committees and of the- 

 scientific officers of the society also bulk largely, including 

 Dr. J. A. Voelcker's account of the experiments in progress- 

 on the farm at Woburn and at the Hills pot-culture 

 station. Turning to the general articles, the interest that: 

 is being manifested in forestry is seen in the two opening 

 papers ; in one Mr. C. E. Curties treats generally of the 

 management of British woodlands, and in the other Mr. R> 

 Anderson deals with the utilisation of home grown timber 

 and its bye products. Mr. Spencer Pickering describes his. 

 experirnents at the Duke of Bedford's fruit farm at 

 Woburn, which he has repeated on a different soil at 

 Harpenden, on the ill effects produced by growing grass- 

 round apple trees. 



The volume is completed by one or two statistical papers, 

 and an article by Mr. A. D. Hall on the manuring of grass 

 land, in which he takes the Rothamsted experiments upon 

 grass land as his starting point, and then proceeds to discuss 

 the many other manurial experiments upon hay or pasture- 

 which are now in progress in various parts of the country. 



MAIDSTONE MEETING OF THE SOUTH- 

 EASTERN UNION OF SCIENTIFIC SOCIETIES.. 

 T^HE ninth annual congress of the South-eastern Union 

 of Scientific Societies opened on the evening of June 9, 

 when Sir Henry Howorth, the outgoing president, resigned 

 his seat to Mr. Henry Rudler, who delivered the annual 

 address at the Town nail, Maidstone. 



Mr. Rudler alluded to his address as a string of common- 

 places, but in it some very important topics were touched, 

 upon. He considered, for instance, the constitution of 

 scientific societies, and the matters to be discussed at their 

 meetings in these days of great specialisation. He divided 

 the mernbers of such societies as constitute the union into 

 those (few in number) who do the work and those (ther 

 majority) -who like to see what is being done. Mr. Rudler 

 was of opinion that the latter should have their wants 

 realised as well as the specialists, for to put it on the lowest 

 plane, the societies generally depended upon the financial, 

 support of those intellectual people who take a general 

 interest in the progress of science without aiding in ic 

 themselves. Mr. Rudler's advice was to hold sectional 

 meetings for the specialists, where the matters to be con- 

 sidered might be as technical as occasion required, and to 



