208 



THE NEW KNOWLEDGE. 



Gaseous stars Highest temperature. 



Metallic stars Medium temperature. 



Carbon stars Lowest temperature. 



Next, on examining the chemical constitution of these 

 three groups, he is able to still further extend our knowl- 

 edge and the foregoing scheme. 



Gaseous stars . . Highest temperature 



Metallic stars . . Medium temperature 



Carbon stars . . Lowest temperature 



. Strong gas of 

 the Helium 

 family and 

 faint enhanc- 

 ed lines. 

 Feeble gas of 

 Helium family 

 and strong en- 

 hanced lines. 



No gas of 

 Helium family 

 and strong 

 arc lines. 



. Faint arc lines. 



The meaning of the foregoing table is briefly this: In the 

 very hottest stars we find almost exclusively the gases hy- 

 drogen, helium, and the gas asterium, which is, so far, un- 

 known on earth. 



In the stars of medium temperature, these gases become 

 replaced by metals in the dissociated state in which they 

 exist in an electric spark of extremely high potential. In 

 the stars of the lowest temperature the gases disappear 

 almost entirely and the metals exist hi the state produced 

 by the electric arc. So rigourous is this division that Lock- 

 yer has been able to construct a relative temperature table 

 of stars in which the stars are arranged in the order of de- 



