March 25, 1887.1 



SCIENCE. 



305 



five years' practical experience, and must possess 

 great advantages for the class of students for 

 whom it is intended. 



A catalogue of minerals alphabetically arranged. By 

 A. H. Chester. New York, Wiley. 

 Professor Chester's catalogue is best described 

 by an extract from its preface: " This list is in- 

 tended to embrace all English names now in use 

 in the nomenclature of mineralogy. It includes 

 species, varieties, and synonymes. Well-authenti- 

 cated species are put in full-faced type. Dead 

 and useless names have been omitted, so that the 

 catalogue can be conveniently used as a check-list 

 and in cataloguing collections." The list seems 

 very complete, and admirably adapted for purposes 

 stated by its author. G. H. Williams. 



THE CHEMISTRY OF THE SUN. 



Me. Lockyer's new book is unquestionably the 

 most important work in the department of astro- 

 nomical physics which has appeared for several 

 years : it is especially interesting and valuable as 

 coming, not from a compiler and dealer in second- 

 hand materials, but from an original worker, who 

 has himself made most of the observations and 

 investigations on which his conclusions depend. 

 We do not mean, however, to imply that he either 

 ignores or is ignorant of the work of others, or 

 fails to make proper use of it : in fact, he brings 

 together a very complete account of all that bears 

 upon his subject, with due credit to his fellow- 

 workers and a generous appreciation of their la- 

 bors and opinions, even when their conclusions 

 differ from his own. 



While the book can perhaps hardly be called a 

 'popular' exposition of its subject, it is certainly 

 not un--populav, — not unnecessarily technical or 

 abstruse ; and the vivid, enthusiastic, perhaps here 

 and there just slightly sensatioFial, style of the 

 author helps to make it attractive : so that it 

 seems likely to be far more extensively read than 

 most volumes of its class. 



The main purpose of the writer is to present the 

 spectroscopic evidence in favor of the hypothesis 

 that our so-called elements are not truly elemen- 

 tary, bvit so constituted that they can be broken 

 up, or ' dissociated,' into still more elementary 

 components by the action of heat ; and that on 

 the sun and stars they are actually so dissociated 

 by the high temperatures there prevailing. 



In the preface, after pointing out the decom- 

 posing power of higher and higher temperatures 

 as actually observed in our laboratories, the author 

 adds as a sort of summary of his argument, " The 

 question then, it will be seen, is an appeal to the 



The chemistry of the sun. By J. Nokman Lockyeb. 

 New York, Macmillan. 8°. . . . 



law of continuity, nothing more and nothing less. 

 Is a temperature higher than any yet applied to 

 act in the same way as each higher temperature 

 which has hitherto been applied has done ? Or is 

 there to be some unexplained break in the uni- 

 formity of nature's processes ? " 



The first seven chapters of the twenty-eight 

 which make up the book are mainly historical, 

 occupied with an account of spectroscopic work 

 previous to 1866, and giving perhaps the best 

 resume of the work of Wollaston, Fraunhofer, 

 Kirchoff, Angstrom, and others, that can be found 

 in the same space. The next three chapters dis- 

 cuss what the writer calls ' A new method in spec- 

 troscopy,' and its results. The 'new method' 

 consisted merely in attaching the spectroscope to 

 a telescope, and studying the spectrum of an 

 object in detail, instead of in gross, so to speak. 

 Huggins seems to have been the first to employ 

 this ' new method ' in his examination of the 

 nebulae in 1864 ; but Mr. Lockyer was the first to 

 employ it upon the solar surface in 1866. 



The results were the recognition of many pe- 

 culiarities in the spectra of sunspots and faculae, 

 the development of the method of observing the 

 chromosphere and prominences without an eclipse, 

 and the detection of remarkable modifications of 

 many lines in the spectrum, such as widenings, 

 reversals, contortions, etc., all significant and evi- 

 dently depending upon the physical conditions of 

 temperature and pressure prevailing at that special 

 point of the solar surface which happens to be 

 imaged on the slit of the spectroscope at the mo- 

 ment of observation. 



This is followed by an account of the author's 

 early laboratory- work, especially his investigation 

 of the so-called ' long and short lines ' in elemen- 

 tary spectra, and the coincident lines in different 

 spectra. This brings us down to 1873, 



The next three chapters discuss the ' diflScul- 

 ties ' that had presented themselves, and seemed 

 to require a remodelling of the received theories. 

 Our space does not permit a presentation of 

 these difficulties here ; but it must sufiice to say 

 that they are such as absolutely to compel us to 

 suppose that a given element, such as iron for in- 

 stance, either gives widely different spectra under 

 different circumstances, the spectrum tending to- 

 wards simplicity under the very highest tempera- 

 tures, or else that it is decomposable. 



This idea, that our elements are only relatively 

 elementary, while really composed of stiU simpler 

 substances, is no new one, as Mr. Lockyer himself 

 points out, but had previously been brought for- 

 ward, and more or less strongly advocated, by 

 Dumas, Brodie, Sterry Hunt, and others, though 

 not on spectroscopic grounds. 



