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TEE POPULAR SCIENCE MONTHLY. —SUPPLEMENT. 



atmosphere, as one went down into it, got more 

 and more complex ; nothing was left behind, but 

 a great many things were added. 



The recent work, so far as I am acquainted 

 with it, has not in any way upset that notion; 

 but what it has done has been to add a consid- 

 erable number of new elements to this reversing 

 layer. Instead of the solar atmosphere consisting 

 of about a dozen elements, it may, I think, pretty 

 definitely be considered as consisting of about 

 thirty. 



To be more exact we had : 



Highest . . Hydrogen. 



Medium . . Magnesium, calcium, sodium. 



Lowest . . Iron, nickel, manganese, chromium, 

 cobalt, barium, copper, zinc, tita- 

 nium, and aluminium. 



There is now evidence that the lower group, 

 which, as I have already said, forms what is termed 

 the reversing layer, really consists of iron, nickel, 

 manganese, chromium, cobalt, barium, copper, 

 zinc, titanium, aluminium, strontium, lead, cad- 

 mium, potassium, cerium, uranium, vanadium, 

 palladium, molybdenum, indium, lithium, rubidi- 

 um, ccesium, bismuth, tin, lanthanum, ylucinum, 

 and either yttrium or erbium. 



Those metals given in italics represent the 

 more recent additions to the list of solar elements. 



At present, therefore, out of the fifty-one 

 metals with which we are acquainted here, more 

 than thirty are known to exist in the sun with 

 more or less certitude. 



Now, it is a very remarkable thing that al- 

 though the metalloids, that is, bodies such as 

 carbon, sulphur, iodine, bromine, and the like, 

 had been very diligently searched for, no evidence 

 that they existed mixed with the metals in these 

 zones — these shells — to which I have referred, 

 has been forthcoming. 



Some years ago, evidence was brought forward 

 of the possible existence of the metalloids as a 

 group outside the metals ; and the evidence for 

 this suggestion was of the following nature : In- 

 dependently of any questions connected with solar 

 physics, all students of science now, I think, agree 

 that the vapors of the various elementary bodies 

 exist in different molecular states ; if these differ- 

 ent molecular states are studied, by means of the 

 spectroscope, perfectly different spectroscopic phe- 

 nomena present themselves. If we use a large 

 induction-coil for instance, we can drive every 

 chemical substance with which we arc acquainted, 

 including carbon and silicon, into a molecular 

 grouping which gives us what is called a line-spec- 

 trum, the spectrum with which we are made fa- 



miliar when we use metals or salts of metals in 

 the electric arc. 



If, however, other conditions are fulfilled, if 

 these bodies are not so roughly handled — if, in 

 other words, we employ a lower degree of heat, 

 or, if we use electricity so that we get quantity 

 instead of tension, then these line-spectra die 

 away altogether, and we have a spectrum, so 

 called, of channeled-spaces or flutings, built up 

 of fine lines, the distances between which are 

 perfectly regular. 



Now, while we got the thirty-three metals to 

 give us line-spectra, the only evidence (very doubt- 

 ful evidence) of the existence of the metalloids in 

 the sun at all depended on the fact that, in the 

 case of iodine and chlorine, some of the chan- 

 neled-space indications given in their spectra at 

 a very low temperature were thought to be traced 

 among the Fraunhofer lines in the spectrum of 

 the sun. 



It is four years ago since evidence was gath- 

 ered of a more conclusive kind in the case of car- 

 bon. The bright flutings due to carbon-vapor 

 in the ultra-violet have their exact equivalents 

 among the Fraunhofer lines. This is the best 

 established piece of evidence, so far as I know, 

 which seems to indicate that we have truly some 

 of the metalloids present in the atmosphere of 

 the sun by the coincidence of their spectra with 

 the Fraunhofer lines. Further, carbon, at all 

 events, we can now say with great probability, 

 exists under such conditions that its molecular 

 structure is very much more complex than that 

 of the metals in the reversing layer, and therefore 

 it exists, probably withdrawn from the excessive 

 heat of the lower region occupied by the reversing 

 layer, which is competent, as we know from other 

 considerations, to drive even carbon and silicon 

 into the extremest stage of dissociation, supposing 

 carbon and silicon to be there. 



The train of reasoning which enables us to 

 suggest that such a temperature must exist in 

 such and such a region of the solar atmosphere, 

 depends, in the main, upon questions raised by 

 the differences between the spectra of certain 

 bodies in the sun and in our laboratories. 



If, for instance, one wishes to observe the 

 coincidence between, let us say, iron and the sun, 

 iron is placed in the electric lamp; the spectrum 

 of the light of its vapor is photographed : above 

 this spectrum, on the same plate, the spectrum of 

 the sun is also photographed ; and, as a rule (I 

 say as a rule, but this is not absolute even in the 

 case of such metals as iron), the intensity of the 

 iron-lines which we get from the iron-vapor in 



