158 



NATURE 



\_Dec, 19, 1878 



" elements " of lower atomic weight. Mr. Lockyer next 

 considers what will be the difference in tho spectroscopic 

 phenomena, supposing that A contains B as an impurity 

 and as a constituent. In both cases A will have a 

 spectrum of its own. B, however, if present as an 

 impurity, will merely add its lines according to the 

 amount present, as we have above explained; whereas 

 if a constituent of A it will add its lines according to the 

 extent to which A is decomposed and B is set at liberty. 

 So that as the temperature increases the spectrum of A 

 will fade if A be a compound body, whereas it will not 

 fade if A be a true element. Moreover, if A be a 

 compound body, the longest lines at one temperature 

 will not be the longest at another. The paper chiefly 

 deals with a discussion from this point of view of the 

 spectrum of calcium, iron, hydrogen, and lithium, as 

 observed at various temperatures ; and it is shown that 

 precisely the kind of change which is to be expected on 

 the hypothesis of the non-elementary character of the 

 elements has been found to take place. Thus each of the 

 salts of calcium, so long as the temperature is below a 

 certain point, has a definite spectrum of its own, but 

 as the temperature is raised the spectrum of the 

 salt gradually dies out and very fine lines due to 

 the metal appear in the blue and violet portions of 

 the spectrum. At the temperature of the electric 

 arc the line in the blue is of great intensity, the 

 violet H and K lines, as they are called, being still 

 thin ; in the sun the H and K lines are very thick, and 

 the line in the blue is of less intensity than either, and 

 much thinner than in the arc. Lastly, Dr. Huggins's 

 magnificent star photographs show that both the H and 

 K lines are present in the spectnim of a Aquilas, the latter 

 being, however, only about half the breadth of the former ; 

 but that in the spectrum of a Lyras and Sirius only the 

 H line of calcium is present. Similar evidence that these 

 different lines may represent different substances appears 

 to be afforded by Prof. Young's spectroscopic observations 

 of solar storms, he having seen the H line injected into 

 the chromosphere seventy-five times, the K line fifty times ; 

 but the blue line, which is the all-important line of cal- 

 cium at the arc-temperature, was only injected thrice. In 

 the spectrum of iron two sets of three lines occur in the 

 region between H and G which are highly characteristic 

 of this metal. On comparing photographs of the solar 

 spectrum and of the spark taken between poles of iron, 

 the relative intensity of these triplets is seen to be abso- 

 lutely reversed ; the lines barely visible in the spark 

 photograph being among the most prominent in that 

 of the solar spectrum, while the triplet, which is promi- 

 nent in the spark photograph, is represented by lines not 

 half so thick in the solar spectrum. Prof. Young has 

 observed during solar storms two very faint lines in the 

 iron spectrum near G injected thirty times into the chro- 

 mosphere, while one of the lines of the triplet was only 

 injected twice. These facts, Mr. Lockyer contends, at 

 once meet with a simple explanation if it be admitted 

 that the lines are produced by the vibration of several 

 distinct molecules. 



" The lithium spectrum exhibits a series of changes 

 with a rise of temperature precisely analogous to those 

 observed in the case of calcium. 



" In discussing the hydrogen spectrum, Mr. Lockyer 

 adduces a number of most important and interesting facts 

 and speculations. It is pointed out that the most re- 

 frangible line of hydrogen in the solar spectrum, //, is 

 only seen in laboratory experiments when a very high 

 temperature is employed, and that it was absent from the 

 solar protuberances during the eclipse of 1875, although 

 the other lines of hydrogen were photographed. This 

 line also is coincident with the strongest line of indium 

 as already recorded by Thalen, and may be photographed 

 by volatilising indium in the electric arc, whereas palla- 

 dium charged with hydrogen furnishes a photograph in 



which none of the hydrogen lines are visible. By em- 

 ploying a very feeble spark at a very low pressure the F- 

 line of hydrogen in the green is obtained without the blue 

 and red lines which are seen when a stronger spark is 

 used, so that alterations undoubtedly take place in the 

 spectrum of hydrogen similar to those observed in the 

 case of calcium. In concluding this portion of his paper 

 Mr. Lockyer states that he has obtained evidence leading 

 to the conclusion that the substance giving the non- 

 reversed hne in the chromosphere, which has been termed 

 helium, and not previously identified with any known 

 form of matter, and also the substance giving the 1,474 

 or coronal line, are really other forms of hydrogen, the 

 one more simple than that which gives the A-line alone, 

 the other more complex than that which gives the F-line 

 alone, 



"There can be no question that the facts brought 

 forward by Mr. Lockyer are of the highest importance 

 and value, and that they will have much influence on the 

 further development of spectrum analysis, to which he 

 has already so largely contributed. But his arguments, 

 are of a character so totally different from those ordi- 

 narily dealt with by chemists that they will hesitate for 

 the present to regard them as proof of the decomposition 

 of the elements until either they are assured by competent 

 physicists that they cannot be Cixplained by any other 

 equally simple and probable hypothesis, or until what Mr. 

 Lockyer has foreshadowed as taking place to such an 

 extent in other worlds has been realised beyond question 

 or cavil in our own laboratories. It has been suggested 

 that the same molecule may be capable of vibrating in 

 different ways at different temperatures, and thus of 

 yielding different spectra, just as a bell may give out 

 different notes when struck in different ways ; and 

 although Mr. Lockyer has replied to this objection, it 

 can scarcely be regarded as finally disposed of. The 

 fact, however, as Mr. Lockyer has pointed out, that the 

 change from the spectrum of a compound to the lowest 

 temperature spectrum of its metallic element is of a 

 similar character to and even less in degree than the 

 change from the lowest temperature spectrum of the 

 metal to the spectra which it furnishes at higher tempe- 

 ratures does not appear to favour such an hypothesis, 

 and from the similarity in the phenomena it is difficult to 

 deny that in both cases decomposition does not equally 

 take place. Prof. Young's observations on the injection 

 of particular lines into the chromosphere during solar 

 storms are also difficult to reconcile with this view, and if 

 the conclusions drawn from previous researches are cor- 

 rect, it also does not account for the short line coin- 

 cidences which led Mr, Lockyer to his hypothesis. 



" Chemists are careful to teach that what are at present 

 regarded as elements are not necessarily simple bodies, 

 but merely substances which they are unable to decom- 

 pose or which they have no special reason to regard as 

 compound bodies. The remarkable relations, both in 

 atomic weight and properties, existing between many of 

 the elements, tend, indeed, to show that they are related 

 in the manner Mr. Lockyer supposes. We sincerely 

 hope that he will continue his researches in this direction, 

 and we trust that at no very distant time he may be able 

 to bring forward evidence sufficiently clear to convince 

 even the most sceptical." 



NOTES 



Mr. J. M. Wilson, Mathematical Master at Rugby School, 

 has been elected Master of Clifton College, in place of Dr. 

 Percival, elected President of Trinity College, Oxford. Mr. 

 "Wilson has done very much for science at Rugby, and, although 

 Dr. Percival is a difficult man to follow, and has done more 

 probably than any head master for the teaching of science in 

 schools, still we hope that Mr. Wilson will prove a worthy suc- 

 cessor to him. 



