366 



NATURE 



[January 28, 1909 



from the time of commencing' the survey until the 

 chart has been produced ready for issue. It contains 

 good descriptions of the various sorts of charts used 

 by seamen, together with much useful information 

 on how to use them in a proper manner. The booli 

 is divided into eight chapters, each one dealing with 

 a separate subject; it is well illustrated, and is a 

 valuable addition to books dealing with hydro- 

 graphical surveying. 



(3) A very useful handbook dealing with general 

 surveying work, levelling, railway curves, and mine 

 surveying; each branch of surveying is well de- 

 scribed, and accompanied by diagrams and practical 

 examples collected from actual field experiences. It 

 is a book which should prove as useful to the profes- 

 sional surveyor as to the student. H. C. Lockver. 



Penrose's Pictorial Annual: a Review of the Graphic 

 Arts. Vol. xiv., 1908-q. The Process Year Book. 

 Edited by William Gamble. Pp. viii -1-208. (London: 

 A. W. Penrose and Co., Ltd.) Price 5^. net. 

 In directing our readers' attention to the annual 

 volumes of this publication, we have year by year 

 pointed out the very excellent nature of' the contents 

 and the very high state of efficiencv which it has 

 attained. .So much care has been bestowed on the 

 reproduction methods, the inks employed, and the 

 other materials used that it seemed nearly impossible 

 that any very conspicuous advance could be made ex- 

 cept after the lapse of a few years. 



Vet in the volume before us we have a proof that 

 such an assumption is incorrect, for one has only to 

 look through the present issue to see how marked" the 

 progress made has been since the last volume was 

 issued to the public. Even the editor, in his prelimin- 

 ary remarlis,_ writes :— " W'e can hardlv realise our- 

 selves how it is possible to continue improving on these 

 mechanical processes as has been shown each year, yet 

 here again is the evidence of the possibility, 'and one 

 IS inclined to wonder what further marvels the future 

 has in store for us." 



U'ith such a wealth of text and illustration included 

 in this volume it is difficult to name any one feature 

 which is more conspicuous than another.' The editor 

 commences, as usual, with his summary of the year's 

 progress in process work, and this is 'followed' by a 

 great number of articles on various branches of 'the 

 subject by well-known workers. The illustrations, 

 \Yhich are, of course, the chief feature of this publica- 

 tion, demonstrate, more than words can do, the excel- 

 lence of the reproduction processes that are now avail- 

 able. All kinds of subjects are dealt with, from the 

 reproduction of an old master to illustrations for boot 

 catalogues, and these suggest the best kinds of process 

 work for the particular subject to be dealt with. 



Perhaps enough has been written to indicate that 

 if anyone wishes to make himself acquainted with the 

 results of process-work of to-day he cannot do better 

 than obtain this handsome and moderately-priced 

 volume. The editor and his co-workers deserve high 

 praise for placing such a useful and valuable publica- 

 tion within easy reach. 



The Edinburgh School Atlas. 32 plates. (Edinburgh 

 and London : W. and A. K. Johnston, Ltd., n.d.) 

 Price IS. 

 A WIDE popularity may be predicted for this remark- 

 ably cheap atlas. The maps are clear, uncrowded, and 

 entirely orographical. There is a good general index 

 showing the latitude and longitude of places included 

 in the maps. It is gratifying'to find that geographical 

 publishers are acquainting themselves with modern 

 needs and producing maps which will assist greatly 

 teachers of geography who adopt scientific method's 

 in their work. 



NO. 2048, VOL. 79] 



LETTERS TO THE EDITOR. 

 [The Editor docs not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he toidertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part 0/ Nature. 

 No notice is taken of anonymous communications.] 



1 he Product and Rays of Uranium X. 



From the present state of the subject it is clear that 

 there is one, at least, and that very probably there are 

 two, intermediate products between uranium X and radium 

 giving- a rays on disintegration. The direct parent of 

 radium has recently been shown by Boltwood (/liner, fotirn. 

 Sci., 1908, XXV., 377) to give a rays of characteristic 

 range. Between the atomic weight of uranium and radium 

 there is a difference of twelve units, corresponding to the 

 expulsion of three a particles, of which only two, that from 

 uranium and that from the parent of radium, so far arc- 

 known. It is true there is a disposition to regard it as 

 probable that the change of uranium into uranium X is 

 accompanied by the expulsion of two o particles, as Bolt, 

 wood (loc. cit., p. 285) has shown that the contribution 

 of uranium in minerals to the total a radiation of the 

 mineral is about twice that of any of the succeeding pro- 

 ducts. 



IVIy recent result on the rate of production of helium 

 from uranium (Nature, December 3, 1908, p. 129) is 

 against this view. In the thorium series — thorium — meso- 

 thorium — -radio-thorium — -thorium X — complete chemical 

 similarity occurs between the alternate pairs — thorium and 

 radio-thorium, mcso-thorium and thorium X — no chemical 

 separation of these pairs having yet been found possible. 

 If the hypothetical product of uranium X similarly was 

 chemically analogous to uranium and gave o rays, the 

 result obtained by Boltwood for the a radiation of minerals 

 might perhaps be explained. In the present state of the 

 subject there is hardly sufiicient evidence that the number 

 of o particles expelled by uranium is exceptional. Further 

 evidence on the question whether an intermediate body 

 exists between uranium X and the parent of radium may 

 be expected so soon as the uranium preparations we have 

 had for many years under observation in this laboratory 

 begin to grow radium, a-; the power of tlie time which 

 the rate of growth follows gives an indication of the 

 number of intermediate stages. Already the results show 

 that if there is not such a body (or bodies) the period of 

 the parent of radium is at least six times as great as that 

 of radium (Phil. Mag., October, 1908, p. 636). 



In the meantime I have attempted — so far without com- 

 plete success — to detect the growth of an o-ray product 

 from very active preparations of uranium X prepared from 

 large quantities of uranium. I have established that there 

 is a feeble residual a radiation remaining from .all my 

 uranium X preparations after the ;8 radiation has decayed, 

 and this residual activity then remains constant. l"he 

 residual o activity of a preparation of uranium X some four 

 or five years old has been kept under careful observation 

 for nine months, and no change of activity has been 

 detected. Newer preparations have shown that the a radia- 

 tion has a practically constant value before the ;8 rays have 

 all decayed, showing that if the a-ray body is .a real pro- 

 duct of uranium X it must be the direct product. The 

 attempt to follow a growth of the feeble a activity simul- 

 taneously with the decay of the intense j8 activity, which 

 the latter view demands should occur, has so far been 

 delayed by the rays showing unexpected properties. I 

 have not yet succeeded in establishing a genetic connec- 

 tion between the a-ray body and the uranium X, so that 

 all that can at present be said is that the results are not 

 opposed to the view that the direct product of uranium X 

 may give the missing a ray of the series, and prove to be 

 the parent of the parent of radium. 



With regard to the 3 rays of uranium X, these until now 

 have been regarded as homogeneous, with a value for 

 Hp of 2000 ; but I liave found that in a magnetic field 

 twice, as strong as that required to prevent ;8 rays having 

 the value 2000 from entering an electroscope, 5 per cent, 

 of the total effect of the /3 ravs still persists. Even in 

 much stronger fields, using sufficiently active preparations 

 of uranium X, the effect of the $ ravs is still marked. It 



