262 



NATURE 



[April 28, 192 1 



the sake of illustration, it is assumed that the 

 average contents were only 2500 tons per acre, 

 the total quantity of this ore could be estimated 

 at 320 million tons. Furthermore, there are no 

 grounds for assuming that these ores are limited 

 to the area above-mentioned ; they may quite well 

 underlie the entire coal-field. For these counties, 

 therefore, it may be asserted without hesitation 

 that the estimate in the report falls very far short 

 of the truth. At the same time it may be said with 

 equal certainty that very little, if any, of this 

 ironstone is ever likely to be wrought, so that, 

 however greatly Sir Aubrey Strahan may have 

 under-estimated the quantity of ironstone that 

 exists in this part of England, the error is of no 

 practical importance whatever. 



The chief practical interest attaches to the 

 report on the ores of the Lias, Oolites, and later 

 formations, for it is to these that the British 

 ironmaster must look for his ore supplies in the 

 future. The work has been done in a most 

 thorough and painstaking fashion, and will no 

 doubt remain the standard work of reference 

 on this subject for many years to come. Most of 

 the figures have already been given in the Sum- 

 mary of Progress of the Geological Survey for 

 19 1 7, but it is greatly to be regretted that the 

 present volume nowhere tabulates the results now 

 arrived at, as has been done for the Carboniferous 

 ores. The Summary above quoted gives as the 

 total amount of reserves of these ores in England 

 more or less developed 1765 million tons, and 

 as the probable additional reserves 2093 millions, 

 or a total of 3858 million tons. The present 

 report gives figures that do not differ very greatly 

 from these, except as regards the Northampton 

 ore. Apparently the total quantity of this ore is 

 now given as 2308 million tons to be gotten from 

 the counties of Northampton, Lincoln and Rut- 

 land, exclusive, apparently, of possible re- 

 serves, whilst the Summary of Progress gaye as 

 the known reserves 1252 millions, and as the 

 probable reserves 976 millions, or a total of 2228 

 million tons. The grand total now arrived at ap- 

 parently amounts to 4154 million tons, so that 

 without insisting on minute exactitude, which is 

 obviously out of the question in such matters, the 

 British ironmaster may take comfort in the 

 thought that he has probably something like 4000 

 million tons of ore at his disposal, and it is inter- 

 esting to note that about one-half of this is repre- 

 sented by the Northampton ironstone. 



These figures are eminently satisfactory, and 

 Sir Aubrey Strahan deserves sincere thanks for 

 this contribution to our knowledge, as well as 

 hearty congratulations on the conclusion of this 

 excellent piece of work. H. Louis. 



NO. 2687, VOL. 107] 



Physical and Inorganic Chemistry. 



Recent Advances in Physical and Inorganic 

 Chemistry. By Prof. A. W. Stewart. With 

 an Introduction by Sir William Ramsay. 

 Fourth edition. Pp. xvi + 286 + v plates. 

 (London: Longmans, Green, and Co., iq?c ) 

 185. net. 



THE popularity of Prof. Stewart's book shows 

 that it meets the requirements of certain 

 kinds of readers. It can scarcely appeal to the 

 serious student of physical and inorganic chemis- 

 try. A good deal of the material dealt with 

 would not commonly be said to belong to either 

 of the branches of chemistry indicated in the title. 

 Much of it is pure physics, such as the long 

 descriptions of X-rays and positive rays, and it is 

 noteworthy that in just these cases good recent 

 monographs by experts, not too large or beyond 

 the capacity of students, are available. Would 

 it not have been wiser to utilise this space 

 for the description of some less accessible recent 

 advances in inorganic or physical chemistry? 



In other cases, notably in the account of the 

 fixation of nitrogen, the author does not appear 

 to have been very critical in his choice of 

 material. A whole chapter is devoted to the per- 

 mutites, which cannot be said to have any general 

 interest, and have a restricted industrial applica- 

 tion. With such matters as the production and 

 utilisation of ozone not dealt with, one could well 

 have spared such unimportant details as these. 



The chapter on absorption spectra seems out of 

 place, since it deals mainly with organic chemis- 

 try, and the general conclusions drawn from the 

 mass of work described are lamentably vague. 

 It may be that " one atom has the effect of stimu- 

 lating another into a certain state of vibration, 

 while other atoms have not this power," but the 

 statement does not take us much further, and 

 reminds one of the conclusion reached by many 

 workers in this and allied fields a few years ago, 

 that the effects were somehow due to " motions 

 of the electrons." These vague generalisations 

 are not of much service. 



It is doubtful whether a whole chapter on arti- 

 ficial transmutation is wise in a book which can be 

 intended only for students. So little which is cer- 

 tain can yet be said in this field that it would per- 

 haps have been wiser to use the space for some 

 more definite advance. After devoting a 

 whole page to the "transmutation" experiments 

 of Ramsay and Cameron, the author can only add 

 that a careful repetition of the work led to nega- 

 tive results. The reviewer is also under the im- 

 pression that Sir E. Rutherford has modified his 

 views on " H-particles," and in any case this 



