February 3, 1898] 



^NATURE 



315 



So much for the purely historic side of the book. 

 There occur in the first pages of the journal notes upon 

 insects, and here and there throughout archaeological 

 jottings ; but the greater part, as one would expect, 

 concerns British plants. The letters are all botanical, 

 and usually express his opinion upon some difficult 

 plant ; the journal contains accounts of his "finds" on 

 the excursions which he made in all parts of the British 

 Isles, in the Channel Isles, and in Iceland. Much, in- 

 deed, is matter of greater interest to the compiler of a 

 local flora than to the general reader. Yet the history 

 of the changes of opinion upon critical plants, and the 

 notices of the discoveries of forms new to our islands, 

 will appeal to many British field-botanists. To sift the 

 synonymy it is necessary to turn to the first index, 

 where, with the exception of the brambles, the nomen- 

 clature of the last edition of Babington's " Manual of 

 British Plants" is followed. One could wish that this 

 sifting of the names had been done in footnotes, in 

 which way it would catch the reader's eye more readily. 

 The index tells us that, on p. i6(), Potamoge/ofi Jlabellatus 

 stands for P. decipiens, and that Euphorbia pilosa appears 

 under five names. Such instances may be here quoted 

 with the remark that reference to this index is very 

 necessary in using the book. 



Lastly, in spite of its many pages, the volume is light ; 

 the printing is excellent, and the portrait at the com- 

 mencement a very true likeness. A second portrait, 

 taken at the age of seventeen, occurs at the commence- 

 ment of the second part, and a pedigree-table occupies 

 a pocket at the end of the book. I. H. B. 



DIAMONDS. 



Papers and Notes on the Genesis and Matrix of the 

 Diamond. By the late Prof. Henry Carvill Lewis, 

 M.A., F.R.S. Edited from his unpublished MSS. by 

 Prof. T. G. Bonney, D.Sc, LL.D., F.R.S. Pp. 69, 

 with 2 plates and 35 woodcuts. (London : Long- 

 mans, Green, and Co., 1897.) 



Diajnonds. A Lecture delivered at the Royal Institu- 

 tion, Friday, June 11, 1897. By William Crookes, 

 Esq., F.R.S. , M.R.I. Pp. 25, with 39 photographs. 

 {Journal of the Royal Institution of Great Britain, 

 1897.) 



AMONG the subjects which attracted the attention of 

 the able and versatile geologist of Philadelphia 

 — whose early death was so deeply mourned both 

 in this country and the United States — was that of the 

 mode of occurrence and the origin of the diamond. 

 At the meeting of the British Association at Birmingham 

 in 1886, Prof. Carvill Lewis read a short paper " On a 

 Diamond-bearing Peridotite and on the History of the 

 Diamond" ; and in the following year he communicated 

 to the Association meeting at Manchester a much longer 

 and more elaborate paper on the same subject, which 

 was entitled " The Matrix of the Diamond." It was well 

 known to Carvill Lewis's numerous scientific friends in 

 this country that he had collected much valuable evidence 

 concerning the association of diamonds with peridotite 

 and serpentine in all parts of the world, and had 

 arrived at certain very definite views concerning the 

 NO. 1475. VOL. 57] 



constant association of the crystalline form of carbon 

 with the ultrabasic rocks. 



Geologists are indebted to Prof. Carvill Lewis's widow 

 for the publication of the work, the title of which stands 

 first at the head of this article, in which these two 

 valuable papers have been printed in full, and to Profs. 

 Bonney and Rosenbusch for the painstaking care and 

 sound judgment with which they have been edited. In 

 the opinion of neither the editor himself nor of Prof. 

 Rosenbusch, were the fragmentary notes on the wider 

 and more theoretical questions connected with the origin 

 of the diamond in such a state as would warrant their 

 publication ; but Prof. Bonney has been able to add a 

 memoir describing the occurrence of rocks similar to 

 that found in the diamond mines of South Africa — to 

 which Carvill Lewis gave the name of " Kimberlite " — 

 from two localities in the United States. These descrip- 

 tions are based on information supplied by Mr. J. S. 

 Diller, of the United States Geological Survey, and by 

 the late Prof G. Huntingdon Williams, of Baltimore, in 

 addition to the notes and specimens collected by the 

 late Prof Carvill Lewis himself. Geologists now possess, 

 in the work before us, the most complete and satisfactory 

 account of the curious rock in which the diamonds of 

 South Africa are embedded ; equal care being devoted 

 to the microscopic structure of the rock, and to the 

 identification of the various minerals present in it. 



Turning our attention from the papers of Carvill Lewis 

 to the lecture of Sir William Crookes, it is impossible to 

 avoid being struck with the great advances which have 

 been made, during the last ten years, in our knowledge 

 of the properties and mode of occurrence of that most 

 wonderful and interesting of all minerals — the diamond. 



The first part of the lecture of Sir William Crookes is 

 occupied with a popular account of the diamond mines 

 of South .Africa and the manner in which they are 

 worked. The author having recently returned from 

 the district, ,where special facilities had been aflforded 

 him for scientific observation, is able to supply a very 

 lively description of the country and its inhabitants, as 

 well as of the operations by which the diamonds are 

 obtained. The reproduction of the photographs with 

 which the lecture was illustrated adds greatly to the 

 value of the pamphlet. 



Concerning the properties of the gem, Sir William 

 Crookes is able to supply much valuable information, 

 recently obtained, concerning the intimate relations be- 

 tween diamond and graphite, and the conversion of one 

 material into the other, and also on the action of the 

 Rontgen rays upon the diamond. As a means of dis- 

 tinguishing true diamonds from all kinds of paste imita- 

 tions, the Rontgen rays appear to be invaluable, for we 

 have here a test which can be applied to cut and mounted 

 materials without any risk of mjury to them. 



In the decade which has elapsed between the reading 

 of the two scientific communications which we have 

 placed at the bead of this notice, the discoveries con- 

 cerning the mode of occurrence and the artificial form- 

 ation of the diamond have been of especial import- 

 ance — and they are admirably summarised by Sir 

 William Crookes in his lecture. 



In 1884 Erofeyev and Lachinov showed that an iron 

 meteorite contained diamonds, and this fact was more 



