334 



NATURE 



[May 19, 1910 



ing the sufifix o5e." This being the case, it seems 

 a little unfortunate that the termination " ide " for 

 the generic names of the groups should have crept 

 into our system of nomenclature. It is equally un- 

 fortunate that our present system recognises no means 

 of distinguishing rotatory sense and configuration, and 

 an official revision of both is urgently needed. 



In conclusion, a word must be added in praise of 

 the excellent bibliography at the end of the volume, 

 the usefulness of which would be greatly enhanced 

 if the references were numbered to correspond to those 

 in the text. Under the present arrangement, refer- 

 ence to the source of information necessitates a 

 reference to the chapter, then to a long list of names, 

 and, finally, to the contents of a whole volume or 

 series of volumes and original papers. J. B. C. 



A PROSPECTOR'S HANDBOOK OF MINERALS. 



The Recognition of Minerals. Being a Collection of 

 Notes and Simple Tests for the Use of Travellers 

 and Prospectors. By C. G. Moor. With Mono- 

 graphs on Geology, Ore Deposits, &c., by Donald 

 A. MacAlister. Pp. vii + 231. (London: The 

 Mining Journal, n.d.) Price ys. 6d. net. 



THE old days of prospecting, when scanty equip- 

 ment and slender knowledge, if backed by 

 sufficient perseverance, were all that was requisite, 

 have gone never to return. The insatiable demands 

 of present-day life for purposes both of peace and war 

 — may be for a filament for an electric lamp of im- 

 l^roved efficiency, or a new alloy to impart exceptional 

 hardness to steel — have enormously increased the 

 range of mineral substances which a successful pros- 

 pector must bring within his purview. In fact, it is 

 necessary for him to have at hand more knowledge 

 than can be conveniently or accurately assimilated by 

 the memory, and he is compelled either to prepare for 

 himself a series of notes or to put in his pocket a 

 book such as that which Mr. Moor has prepared. 

 Himself a traveller, Mr. Moor writes with the under- 

 standing of one who knows what exactly is the in- 

 formation required, and many of the sections, for 

 instance, those dealing with the subjects of " panning " 

 and "vanning," contain much detail of great practical 

 value which may save the novice much time, trouble, 

 and annoyance. To give that basis of theoretical 

 knowledge which makes the radical difference between 

 an intelligent understanding of the principles of the 

 methods and merely blind rule-of-thumb working, 

 several important monographs by Mr. MacAlister have 

 been incorporated in the book. He has followed the 

 customary treatment of the subjects, and discusses 

 them in sufficient fulness for the purpose in view. 



In the recognition of minerals, which, as the title 

 tells us, forms the main subject of the book, reliance 

 is placed upon the colour as an initial criterion. It 

 is, as Mr. Moor points out, far from a constant 

 character of most species, and, moreover, suffers from 

 the disadvantage that the terms in which it is ex- 

 pressed are wanting in precision, and that the appre- 

 ciation of delicate differences varies considerably with 

 NO. 2 1 16, VOL. 83] 



the individual. On the other hand, it is the most 

 obvious of the physical characters, and suffices for a 

 preliminary separation. The range is subsequently 

 narrowed by the crystalline form, if any, and by 

 determinations of the hardness and the specific gravity, 

 until the identity of the mineral is established; the 

 conclusion may be confirmed by the application of a 

 few simple blowpipe and other chemical tests which 

 are possible with a prospector's outfit. A full descrip- 

 tion of each mineral is given under the colour which 

 most commonly characterises it, but cross-references 

 are added under the less usual colours. The data 

 that are given for each species include the hardness 

 and the specific gravity, the ordinary chemical re- 

 actions, the localities where it has been found in 

 workable quantity, and its commercial value. At the 

 end of this section useful lists, are added of minerals 

 soluble in water, hydrochloric acid, and aqua regia, 

 and of minerals which are unaffected by these liquids. 

 The section that follows on the metallic and non- 

 metallic elements is particularly useful, because this 

 information is not contained in a text-book on 

 mineralogy. L'nder each element is given a list of 

 the principal minerals in which it occurs, their phy- 

 sical and chemical characters, and particulars of its 

 commercial use and value. Other sections deal with 

 the important subjects of the working of the lodes 

 and the extraction of the metal desired ; a special 

 section in the appendix is devoted to the extraction of 

 gold. Mr. Moor mentions the precious stones, but 

 gives few details, and refers the reader to two works 

 the scope and nature of which he describes in the 

 appendix. Of these one is quite satisfactory, though 

 costh' and too large for a traveller to carry about ; but 

 the other is full of mistakes in facts and principles, 

 and is likely to prove a broken reed ; it is strange 

 that Mr. Moor should so strongly recommend it. 



The book originally appeared in parts in the 

 columns of the Mining Journal, and this fact may, 

 perhaps, account for the eccentric pagination, the 

 first page coming in the middle of the introduction, 

 and for the division into sections and not into well 

 separated chapters. The text is printed on the right- 

 hand page only, the other being left blank, presumably 

 for the addition of notes; interleaving would have 

 been a neater and equally effective method. The 

 index is fairly complete, but why should an irrelevant 

 advertisement have been sandwiched between it and 

 the text? 



ELECTRIC DISCHARGES THROUGH GASES. 



Conduction of Electricity through Gases and Radio- 

 activity — a Text-book with Experiments. By Dr. 

 R. K. McClung. Pp. xvi + 245. (Philadelphia: P. 

 Blakiston's Son and Co., 1909.) Price 1.50 dollars 

 net. 



THOSE teachers of physics who are considering the 

 desirability and practicability of introducing 

 into their more advanced courses of laboratory work 

 some experiments on the discharge of electricity 

 through gases and on the phenomena of radio-activity 

 will find this book a useful guide. Believing that our 



