238 THE DISCOVERY OF NEW ELEMENTS. 



ersed and enveloped by silicates, and which have an amount of phos- 

 j)horus and carbon, as well as of hydrogen and nitrogen, as insignificant 

 in proportion as is tbat of the earth, all of which makes it seem prob- 

 able that they have had a gaseous envelope that has been lost during 

 their passage through the terrestrial atmosphere. 



But if the elements of low specific gravity or great volatility which, 

 like hydrogen or nitrogen, exist in great quantity around us form but 

 a very small part of the total constituents of our globe, it will be seen 

 that the elements called rare must compose but an infinitesimal part of 

 the mass of the earth, especially since, as far as we know at present, 

 these elements are never found at great depths. I at least am not 

 aware that the heavy metals — gold, silver, lead, etc. — are found in mate- 

 rials extracted from great depths or thrown out by volcanoes. At the 

 time of the great eruption of Krakatoa. for example, I sought vainly 

 for such elements in the cinders ejected by the volcano, which appar- 

 ently came from great dei)th8. The supposed discovery of a new ele- 

 ment in the old lavas of Vesuvius has been found to be erroneous. 



As we approach tlie surface of the globe elementary bodies seem to 

 multiply, and two hypotheses occur for explaining this — displacements 

 of cosmic matter or the formation of new elements upon the surface of 

 the globe. 



Displacements of cosmic matter are, as is well known, incessant. 

 The fall of meteorites furnishes a particularly striking example of this, 

 but it is probable that quantitatively cosmic dust has a greater impor- 

 tance. Still, neither the meteorites found at various points nor the 

 dust gathered by Nordenskiokl ' on the ice fields of the polar regions, 

 and whose extra-terrestrial origin can not be doubted, contain rare ele- 

 ments. The hypothesis of increase by exterior agency seems, then, to 

 lack foundation. The new formation of elementary bodies seems, how- 

 ever, still less probable. We can, at most, support it by the hypothe- 

 sis, suggested but never proven, that bodies now supposed to be sim- 

 ple may be reduced. Without doobt spectrum analysis reveals to us 

 transformations that are gradually going on in the matter of the fixed 

 stars, but the question is whether known elements transform them- 

 selves into others equally well known. Besides, the conditions of tem- 

 perature and aggregation of the fixed stars that have been observed 

 can not be compared with those of the earth. 



Evidently the in(;rease of simple bodies in the exterior strata of the 

 terrestrial globe is only apparent. It must be recognized that human 

 science has made great progress and that this progress can not 

 but have an influence ui)on the discovery of new elements. The first 

 electrolytic decompositions of salts and earths attempted at the com- 

 mencement of tliis century by Davy by means of a feeble Voltaic pile 

 demonstrated the existence of metallic radicals that had not been in 

 the least suspected up to that time; while Moissan, by means of the 

 powerful currents used to-day, has been able to isolate from its combi- 



' Nordenskiold. Pogg., Ann., 151. 



