DIASTROPHISM AND THE FORMATIVE PROCESSES 481 



In reaching conclusions respecting the central temperature 

 there is not only the danger of error due to deducing it from com- 

 pression computed according to this doubtful law, but there are 

 other sources of uncertainty, among which one of the more serious 

 is the unknown amount of heat removed by inherited eversive 

 movements within the body, co-operating with ordinary convection 

 while the formative processes were in progress, and since. In the 

 distinctly large bodies these might not perhaps rise to decisive 

 value, but in the smaller orders of bodies the central temperature 

 theoretically assignable to concentration might be so far dissipated 

 by the combined effects of inherited eversive movements, convec- 

 tion, conduction, and viselike mechanical action (discussed below) 

 that it would have but limited effect on the physical state of the 

 core into which the nucleus passed. 



A further serious difficulty in estimating central temperature 

 arises from our ignorance of what part of the potential energy 

 theoretically set free by compression went into endothermal re- 

 organizations, what part became latent in forming solutions, what 

 part was carried surfaceward by the forced ascent of these solutions, 

 and what remained to increase the temperature. 



THE GROUP OF FACTORS THAT CONDITIONED THE PROCESS OF 

 NUCLEAR CONCENTRATION 



The passage of the planetary nuclei from their original states as 

 solar gases into their final states as the cores of planets, planetoids, 

 and satellites was by no means so simple a process as gaseous 

 condensation has usually been regarded. Beside the simple con- 

 densing process, as usually considered, there were co-operating 

 activities that radically modified the general tenor of the process. 

 Four of these require consideration: 



I. Several types of motion were inherited from the solar eruption, 

 and these took the lead in determining the internal circulation. The 

 thermal convection, as it arose, was superposed on these. 



II. A sifting of the mixed molecules of the original gaseous matter 

 set in almost as soon as it emerged from the sun and changed the mixture 

 to the proper proportions for forming planetary cores. 



III. The formation of precipitates also set in early, and gradually 

 changed the primitive gases into Brownian mixtures which themselves 



