July 21, 1898J 



NATURE 



269 



groups the felspars, the felspathoids, the micas, the 

 garnets, the epidotes, the tourmalines, the zeohtes, and 

 the chlorites. Among the metasihcates we find the 

 pyroxenes and amphiboles, with serpentine beryl and 

 the copper silicates. The table of classification given at 

 the end of the work includes most of the common rock- 

 forming minerals, but does not deal with the rarer species. 

 The author finds himself unable to accept Prof. E. 

 Dana's nomenclature of the silicates, and, as will be seen 

 from the foregoing summary, uses the terms orthosilicates 

 and metasihcates for groups having very different limits 

 to those assigned to them by the American mineralogist. 



The Blood ; how to examine and diagnose its Diseases. 



By Alfred C. Coles, M.D. Pp. xi + 260. Plates vi. 



(London : J. and A. Churchill, 1898.) 

 The book before us is practically confined to the con- 

 sideration of morphological methods. The author has 

 endeavoured to collect what is known concerning the 

 morphological changes as determined by staining re- 

 agents in the cellular elements of the blood in different 

 diseases. He has further included a description of the 

 methods requisite for the identification of certain para- 

 sites, and Widal's method of serum diagnosis in typhoid 

 fe\er. The information contained in the book is, so far 

 as concerns method, accurate ; and those who prefer to 

 have the methods for the examination of the blood in one 

 volume, not under the head of the respective disease, as 

 is done in the larger text-books of medicine, will no doubt 

 find Dr. Coles' work useful. Some of the author's 

 explanations and definitions are, however, not as exact 

 as they should be ; for instance, his remarks on chemio- 

 taxis on p. 86, especially on negative chemiotaxis, are 

 certainly original. The terms are not ordinarily used in 

 the sense of the author. More might also have been 

 done in the direction of a fuller bibliography. 



F. W. T. 



Notes on Volumetric Analysis. By Arthur Thornton, 

 M.A., and Marchant Pearson, B.A. Pp. viii + 80. 

 (London : Longmans, Green, and Co, 1898.) 

 The series of twenty-seven expsriments described in this 

 book will serve as an elementary course of practical work 

 in volumetric analysis, as they illustrate all the simple 

 processes of neutralisation, oxidation, iodometry, and 

 methods of precipitation. The instructions are clear ; 

 and the student who follows them should have no difficulty 

 in performing the experiments, or in carrying out other 

 exercises of the same type, while at the same time he 

 should become skilful in general volumetric work. 



A First Year's Course of Practical Physics^ adapted for 

 Beginners and Junior Students. By J. F. Tristram, 

 M.A., B.Sc. Pp. 50. (London : Rivingtons, 1898.) 

 A SERIES of very elementary exercises on measurements 

 of length, area, volume and density are given in this 

 little book. Neither the plan of the book, nor the 

 experiments described, present any novelties ; but this 

 will not prevent the volume from being of use in instruct- 

 ing young pupils in the methods of weighing and 

 measuring. 



The Doctrine of Energy : a Theory of Reality. By 

 B. L. L. Pp. ix -f- 108. (London : Kegan Paul, Trench, 

 Triibner, and Co., Ltd., 1898.) 

 The argument that the conception of energy embraces 

 and supersedes the conception of matter ; that, in fact, 

 the universe is not made up of two real things — matter 

 and energy — but only one, was supported by the author 

 from the standpoint of physical science in a volume 

 published eleven years ago. The question is now pre- 

 sented as viewed from a metaphysical standpoint, and it 

 will doubtless prove as interesting to students of philosophy 

 as it is to students of physics. 



NO. 1499, VOL. 58] 



LETTERS TO THE EDITOR 



[ The Editor does not hold himself responsible for opinions eX' 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part <y Nature. 

 No notice is taken of anonymous communications.l 



Solfatara Gases. 



We have for a considerable time been occupied with an 

 extensive study of the gases emanating from the earth in various 

 parts of Italy with the object of detecting the presence of argon 

 and helium, and possibly of other elements they may contain. 



The first part of this work has already been published (CaJ 

 delle tervie di Abaiio, Gazzetta Chimica Italiana). 



We are now completing the study of the gases of the Solfatara 

 di Pozzuoli, Grotta del Cane, Grotta ammoniacale, and of 

 Vesuvius. In the spectrum of those of the Solfatara di Pozzuoli, 

 which contain argon, we have found a sufficiently bright line 

 with the wave-length 531 "5, corresponding to that of corona 

 1474 K, attributed to coronium, an element not yet discovered, 

 and which should be lighter than hydrogen. This line has 

 never before been observed in earthy products. Besides we 

 have noted the following lines: — 653"5, 595'5, 536*2. In the 

 spectrum of the gases gathered from the Fumarole of Vesuvius 

 we have observed the lines : — 769'5, 631 "8, 572*5, 636 5, 441 '5, 

 and again 595 5. All these lines do not belong to the spectrum 

 of argon or helium ; they show a coincidence or proximity only 

 with some unimportant lines of various elements, such as iron, 

 potassium, titanium. Considering the conditions of our experi- 

 ments, the presence of these elements in the gases we have 

 studied is not probable. The line 572*5 is near to one of 

 nitrogen, but being the only visible line of the spectrum of this 

 gas, it cannot be attributed to it. Besides coronium we have 

 thus probably other new elements in these gases. 



We are diligently pursuing their investigation. 



Padua. R. Nasini, 



^ F. Anderlini, 



R. Salvadori. 



The Spectrum of Metargon. 



The letter which Messrs. Ramsay, Travers and Baly have 

 addressed you on this subject calls for one or two remarks. The 

 similarity between the carbon and metargon spectra does not 

 only apply to the green band, but to the whole of the visible 

 spectrum, and also, as my previous letter pointed out, to the 

 ultra-violet band commonly ascribed to cyanogen. With the 

 ordinary coil discharge I could see nothing but carbon bands, 

 and it is contrary to all experience that tsvo dissimilar bodies 

 should give complicated spectra so much alike that a two-prism 

 spectroscope can detect no difference between them. With the 

 Leyden jar a strong continuous spectrum appeared, and, over- 

 lapping it, some of the lines of argon. The blue argon lines were 

 absent, but my examination was not sufficiently detailed to allow 

 me to say, that the visible lines were those commonly found in 

 the "red spectrum." Neither with nor without the jar did I 

 see any line which could not be assigned either to carbon or to 

 argon, but I should have liked to try a stronger jar and a more 

 powerful ceil. With the jar there seemed to me to be signs of 

 decomposition of the gas, as, on removing it again, the carbon 

 lines were weak at first and only gradually returned. The pres- 

 sure in the tube was rather high ; and if the tubes experimented 

 upon by Prof. Ramsay and his coadjutors were all at the same 

 pressure, I should not attach much weight to their observation 

 that the carbon oxide spectrum did not make its appearance 

 after introduction of oxygen, for that spectrum only shows well 

 at lower pressures. 



I ask for nothing more than a "suspension of judgment" 

 until a more detailed spectroscopic exammation has been made. 

 Only such an examination should include observations at atmo- 

 spheric pressures, and also at lower pressures than those used 

 so far. 



It is also highly desirable to try Leyden jar sparks of much 

 greater intensity than those I saw used at University College. I 

 agree with Prof. Ramsay in so far that the brilliancy and whole 

 appearance of the carbon spectrum does not suggest its being 

 due to an impurity. Taking the spectroscopic evidence by itself, 

 it points in the direction that the gas under examination is a 

 compound of carbon either with argon or with a so far unknown 

 body, and that it may be mixed with a considerable quantity of 



