Reviews — Useful Minerals and Rocks. 177 



bubbles of gas, even 30 feet in. diameter, burst without giving any 

 explosion whatever. 



The nitrogen of the emanation was handed over to Professor R. W. 

 Wood for examination for rare gases. The result was negative ; and 

 the absence of argon is taken as a further proof that the volcanic 

 gases had been successfully collected free from atmospheric contamina- 

 tion. It is further held by the authors as an indication that the 

 magmatic nitrogen was not originally atmospheric in origin. Here it 

 ■seems to the writer that there is room for doubt. Is it not possible 

 that nitrogen possesses an advantage over argon either in the process 

 of diffusion through solid rock-masses or perhaps in that of solution 

 by silicate magmas? However, Day & Shepherd are satisfied that 

 magmatic nitrogen is an essentially original constituent, and conclude 

 that magmatic water is in all probability in a like category ; for water 

 above its critical temperature loses the advantage due to surface 

 tension, which is the basis of Daubree's famous experiment. 



E. B. Bailet. 



III. — The Deposits of the Useful Minerals and Rocks, their Origin, 

 Form, and Content. By Professor Dr. F. Beyschlag, Professor 

 J. H. L. Vogt, and Professor Dr. P. Krt/sch. Translated by 

 S. J. Truscott. In three volumes. Vol. I : pp. xxviii+514, 

 with 291 illustrations. London : Macmillan & Co., Ltd., 1914. 

 f MHE authors of the original German edition, all three of whom are 

 X among the foremost living authorities on the subject, have 

 planned a most comprehensive and ambitious treatise on ore-deposits. 

 When they complete their project they will have included within 

 their purview not only ore-deposits as ordinarily understood, that is 

 to say those metalliferous in character, but also deposits of coal, salt, 

 •and mineral oil, and will have therefore covered the whole range of 

 minerals and rocks which have been mined. The first volume 

 appeared in 1910; the second volume was published in two parts, 

 the first in 1912 and the second in 1913. This treatise differs from 

 the earlier standard works on the subject (viz., Dr.. Richard Beck's 

 Lehre von den Erzlager&tdtten, of which a third edition appeared in 

 1910, and Die JErzlagerstdtten, began by Professor Stelzner and com- 

 pleted by Dr. Alfred Bergeat, which was published in parts, i and ii 

 in 1904 and iii in 1906) in that the discussion is based upon broad 

 geological principles; while in the two works mentioned the 

 tendency has been more to bring together copious and detailed 

 descriptions of the important mining regions. 



The volume we have before us is the English translation of the 

 first volume of the German edition. The task of preparing the 

 translation has been undertaken by Mr. S. J. Truscott of the Royal 

 School of Mines, London, and has been admirably performed. In his 

 preface he modestly says, " I have endeavoured faithfully to bring out 

 both the fact and the spirit of the authors' work, this being of such 

 high standard that the reception of a translation must depend largely 

 upon the degree of closeness with which the original is approached." 

 There can be no question of his success, but, we may add, he has not 

 adhered so slavishly to the original as to mar the ease of diction : 



DECADE VI. — VOL. II. — NO. IV. 12 



