THE DISCOYEEY OF NEW ELEMENTS WITHIN THE LAST 

 TWENTY-FIVE YEAKS.i 



By Clemens Winkler. 



In considering: the relative frequency of the substances composing 

 the crust of the earth, Clarke^ admits that down to a depth of 10 kilo- 

 meters below sea level the composition of that envelope is the same as 

 that of the superficial strata already examined. The average specific 

 gravity of these strata is 2.5, which is not much more than half that 

 of the earth, taken as a whole. Including the ocean and the atmos- 

 phere, this outer crust is half oxygen and one-fourth silicon, the remain- 

 ing fourth being made up of the other elements: Aluminum, 7 per cent; 

 iron, 5.1; calcium, 3.5; magnesium, 2.5; sodium, 2.2, and the same 

 amount of potassium. Some elements, whose numerous combinations 

 have long attracted the attention of the human mind, are of but slight 

 importance quantitatively considered; thus, there is found in the crust 

 of the earth but 0.94 per cent of hydrogen, 0.21 of carbonic acid, 0.09 

 of phosphorus, and 0.02 of nitrogen. Tliese elements, therefore, which 

 form immense oceans, and are the very basis of life, furnish but a very 

 small fraction of the above-mentioned external shell, 16 kilometers 

 thick, and it seems probable, from soundings hitherto made, that at 

 the greatest depths they are absent or exist in very small quantities. 

 Considered with reference to the mass of the whole globe they may be 

 almost wholly neglected. The amount of chlorine does not exceed 0.15 

 per cent; yet the amount of chloride of sodium dissolved in the ocean 

 would suffice to cover the surface of the continents and bury the 

 highest mountains. 



It will be seen from this how little we can judge of the average mass 

 of the globe, as indicated by its mean density, from an examination of 

 its external surface. There can not be the least doubt but what the 

 internal portions of the earth are formed from substances different 

 from those composing its external strata, and involuntarily the mind 

 compares our planet with those meteorites whose mass is of iron trav- 



1 A paper read January 11, 1897, before the German Chemical Society at Berlin. 

 Translated from the Revue Scientifique, fourth series, Vol. Vlll, pages 258-262. 



^F. W. Clarke, Bulletin of the Philosophical Society of Washington, Vol. 11, 

 pages 129-142. 



237 



