626 



TABLE 662.— CHEMICAL COMPOSITION OF EARTH— METEORITES AND 

 SOLAR ATMOSPHERE* 205 



The table gives log NH, where NH = the number of atoms, neutral and ionized, per 

 cm 8 . Constants added to data of Russell and Brown to give order of magnitude agreement 

 with Unsold. : indicates less accuracy ; ? origin doubtful. 



H and He are about 97 percent of the total solar mass, the oxygen group 2.7 percent, 

 the metals 0.3 percent; and by numbers of atoms 99 percent, 0.9 percent, and 0.1 percent 

 respectively. 



The level of ionization in the solar atmosphere is such that atoms of IP = 8.33 ev are 

 50 percent ionized; ionization temperature = 5676° K ; electron pressure «* 32 bar; 85 

 percent of free electrons come from Mg, Si, Fe, according to Unsold. 



* Prepared by B. Bell. 



205 Brown, Rev. Mod. Phys., vol. 21, p. 625, 1949; Russell-Dugan-Stewart, Astronomy, vol. 2, p. 503, 

 1938: Unsold, Zeitschr. f. Astrophys., vol. 24, p. 307, 1948. 

 t Brown. t Russell. §Unsold. 



TABLE 663.— COSMIC ABUNDANCES OF THE RARE GASES* 



As estimated by interpolation of the abundance curves (abundances in atoms per 10,000 

 atoms of silicon). 



Isotope used Estimated 



for inter- abundance 



Gas polation of isotope 



Ne Ne 21 100 



A A 38 1000 



* For reference, see footnote 204, p. 625. 

 SMITHSONIAN PHYSICAL TABLES 



