COMPOSITION OF OUR XJNIVERSE — BROWN 



205 



seismic-wave studies. Knowing the location of the core boundary 

 and the density of iron as a function of pressure, the mass of the core 

 can be readily determined. It is found on such a basis that the ratio 

 of the weight of the core to the weight of the mantle is approximately 

 0.5. If one assumes that the mantle contains an amount of metal 

 phase equivalent to that found in stony meteorites, the weight ratio 

 of metal to silicate for the earth as a whole would be approximately 

 0.6 or 0.7. 



CM 





0)Cidu 



Figure 1. — Distribution of elements in the earth. 



Utilizing the above figures for the ratio of metal to silicate, and 

 replacing many of Goldschmidt's abundances with more recently de- 

 termined values, a revised set of abundances of elements in gross mete- 

 oritic matter has been computed and has been published in the Review 

 of Modern Physics, October 1949. 



In spite of the errors involved (primarily in the solar data), the 

 abundances of the elements in gross meteoritic matter correspond quite 

 well with the abundances of these elements as found in the sun, in- 

 dicating strongly that insofar as certain elements are concerned, me- 

 teorites possess essentially the same composition as the sun. All 

 the elements in question possess relatively high boiling points, or their 

 oxides possess high boiling points. In other words, it appears reason- 

 able to assume that, with respect to easily condensable substances, 

 meteorites and the sun possess nearly identical compositions. Fortu- 

 nately, altliough these elements constitute less than one-half of 1 

 percent of the mass of the sun, they include no less than Yl of the stable 

 or long-lived elements existing in nature. Thus, it appears that a 

 study of the relative abundances of elements in meteorites can give us 

 important abundance information which covers a wide range of ele- 

 ments, and which has considerable cosmic significance. 



