PAPERS PRESENTED AT GENERAL SESSIONS 63 



that our o^\ti atmospli-ere would be increased three-hun- 

 dred times if the oceans were vaporized. The earth 

 would be covered with a thick mantle of clouds and the 

 diameter of the earth as measured by an obseixer on 

 some other planet would be noticeably increased and 

 the mean density consequently decrea&ed. Kising tem- 

 peratures with increasing masses would give exactly the 

 reverse of the condensation hy]3oth€sis; the solid mass, 

 would gradually pass over into the gaseous state. No 

 explosion would occur if the body under discussion were 

 built up slowly so that the process of adjustment was 

 gradual and not by the necessities of the case a violent 

 one. 



While this change in the physical state is in progress 

 there is a decline in the mean density since the conver- 

 sion of a solid into a gas would result in a considerable 

 increase in volume. But if a mass already gaseous should 

 be still further increased, the resulting increase in pres- 

 sure would result in a greater density for there would 

 be no increases of volume due to the conversion of solids 

 into gases. 



If the assumption that Saturn is wholly gaseous is 

 correct, then we should expect Jupiter, which is slightly 

 more than three times as massive as Saturn, to be more 

 dense than SatuiTi and this is actually the case, for the 

 density of Jupiter is 1.25, or about twice that of Saturn. 



If we had a planet three times as massive as Jupiter 

 we should expect it to be more dense than Jupiter for 

 the same reason that Jupiter is more dense than Saturn. 

 But this process of increasing density with increasing 

 mass could not go on indefinitely with gaseous masses 

 any more than it could with solid masses. The heat 

 generated by the high temperatures and pressures in the 

 interior would increase greatly ^yith larger masses until 

 the expansive tendencies due to the heat generated just 

 balanced the compressive elfects due to gravitation, and 

 there would be a second maximum in the densities. For 

 still greater masses the expansive forces of heat would 

 exceed the compressive forces and the density would 

 again decline. We have no means of knowing for what 



