July 23, 1903] 



NATURE 



267 



j nitrogen, metal nitrides, phosphorus compounds of 



' nitrogen, arsenic nitride, carbon compounds of 



nitrogen, silicon nitride, titanium compounds of 

 nitrogen, zirconium nitride, boron compounds of 

 nitrogen, nitrogen in closed rings, alkaloids, protein 

 substances, analytical methods, addenda. 



The treatment of the element and its important in- 

 organic compounds, e.g. nitric acid and ammonia, 

 seems very satisfactory, although, for instance, the 

 action of hypobromite on ammonium chloride might 

 well have been included in the list of methods of pre- 

 paring nitrogen, instead of merely being referred to 

 incidentally in another connection. 



Apparently no attempt has been made to sift critic- 

 ally the large accumulation of material at the author's 

 disposal, and the book therefore assumes the character 

 of a dictionary. Nevertheless, several cases are to 

 b3 found where a more connected treatment is given 

 to the subject, as, e.g. in the description of the steps 

 by which the formation of nitric acid in the soil was 

 traced to a specific ferment, or in the account of the 

 application of Werner's theories to the constitution of 

 the metal ammonia compounds. Such accounts, al- 

 though written in briefest outline, serve to direct atten- 



^ tion to points of importance in theoretical chemistry. 



\ The account of the diazo-compounds one could wish 



fuller, and some reference might have been expected 

 to Goldschmidt's important work on the dynamics of 

 the diazo- and azo-compounds. In mentioning the 

 transformation of ammonium thiocyanate (the melt- 

 ing point of which is 149°, not 159") into thio-urea, 

 also, the work of Waddell might have been referred to. 

 Further, in the analytical portion of the book, although 

 various methods are given for the estimation of 

 nitrogen in organic compounds, no mention is made 

 of the Frankland-Armstrong modification of Dumas 's 

 method, although it is probably the most convenient 

 and accurate method of estimation. 



In compiling the book, the chemical literature up to 

 1900 has been taken into account ; and in an appendix 

 additions and corrections are given bringing the work 

 up to 1902. In spite of some omissions, the book will 

 be readily welcomed as an important addition to the 

 works of reference in chemistry, and the author de- 

 serves the thanks of his fellow-workers for the trouble 

 he has taken in the compilation. A. F. 



FROSPECTl^G. 



La Prospection des Mines et leur Mise en valeur. By 

 Maurice Lecomte-Denis. Pp. xv + 551, with 320 

 figures. (Paris : Schleicher, 1903.) 



WHEN an author is fortunate enough to have 

 such a godfather for his book as M. Haton de 

 la Goupilliere, it may be taken for granted that the 

 work contains much useful matter. The book is in- 

 tended not so much for the old-time prospector, armed 

 with pick, shovel, and pan, who wanders about in 

 search of gold, as for the scientific mining engineer 

 called upon to report upon a mineral deposit already 

 discovered, and possibly already worked on a small 

 scale. M. Lecomte-Denis tells the novice how to set 



NO. 1760, VOL r^si 



about his work, and how to draw up his report to his 

 employers, and he points out useful precautions to be 

 observed in purchasing mines and minerals. The 

 motto for the chapter upon " salting," " Defiance est 

 mere de siireU," is well chosen; many of the common 

 tricks of fraudulent mine-vendors are exposed by the 

 author, who most wisely advises the inspecting en- 

 gineer to err on the side of scepticism when making 

 his examinations. 



Next come two purely geological chapters upon the 

 distinctive characters of the igneous and of the 

 sedimentary rocks. It is doubtful whether it is wise 

 to burden a book upon prospecting with more than 

 three hundred figures of fossils. M. Lecomte-Denis 

 points out, however, that the traveller cannot carry a 

 geological library with him, and that it will probably 

 be a convenience to him to possess a little palaeonto- 

 logical information for immediate reference on the 

 spot. 



Six chapters are devoted to the study of the modes 

 of occurrence of the most important useful minerals, 

 viz., coal, petroleum, bitumen, and the ores of iron, 

 copper, zinc, and lead. Many useful commercial data 

 are appended. Similar information concerning phos- 

 phates, bauxite, and the ores of tin, mercury, &c., is 

 promised in a later edition. 



When a mineral deposit has been found, it is usually 

 necessary to investigate its commercial value by cer- 

 tain preliminary workings. The manner of carrying 

 these out and of making deductions from the results 

 obtained is treated in a long and useful chapter. The 

 author speaks wisely with regard to writing reports 

 when he bids the engineer weigh his words very care- 

 fully, for extracts may be made, and words may be 

 twisted, so as to convey a meaning very different from 

 that which was intended. The greatest prudence is 

 necessary on the part of inspecting engineers with 

 the object of not raismg his employer's hopes too 

 high, nor, on the other hand, by an unnecessarily 

 pessimistic tone, of preventing him from embarking 

 upon an undertaking which may have many chances 

 of success. What is required is complete frankness; 

 let the capitalist know the grounds upon which the 

 engineer bases his opinions. If the former is in doubt, 

 he can then go to a consulting mining engineer and 

 say, " Supposing these data to be true, what is your 

 advice? " 



The inspecting engineer should certainly make him- 

 self acquainted with the mining laws of the country 

 in which the property upon which he is reporting is 

 situated ; and the brief remarks of M. Lecomte-Denis 

 upon foreign mining jurisprudence may serve as a 

 first step in the study. On the other hand, more 

 space is devoted to an exposition of the mining laws 

 of France than seems to be necessary. 



The tables at the end of the book are similar to 

 those found in the usual miners' pocket-books. Some 

 palpable errors show that sufficient care was not 

 taken in preparing them for the press, and conse- 

 quently the reader may feel a little sceptical about 

 their trustworthiness. On the whole the book is likely 

 I to prove useful to the mining engineer, for it deals with 

 I matters which are usually considered somewhat out- 

 side the scope of the ordinary text-books. 



