DIASTROPHISM AND THE FORMATIVE PROCESSES 489 



ever, to be definitely implied by a posteriori reasoning from the 

 existing bodies. The present line of attack shows that the nuclei, 

 except the four of the giant order, were little more than the residues 

 of the heavier material left by selective molecular action working 

 on larger original bodies of mixed gases. This seems to apply to 

 all satellites, to all planetoids, and, in qualified degrees, to all 

 planets from the earth downward. 



The process of evaporation had the effect of reducing the energy 

 of the residue per unit mass, and this, added to the inevitable loss 

 by radiation, made control increasingly secure and caused loss 

 to diminish till it became negligible. 



III. The formation of precipitates and of Brownian mixtures, 

 grading into quasi- gaseous clouds of precipitate aggregates. — As the 

 original mixed gases emerged from the sun, expansion, abetted by 

 radiation, must have promptly lowered the temperature, and this 

 lowering of temperature doubtless led to the formation of precipi- 

 tates. It is immaterial just here whether these precipitates were 

 formed by simple cooling or by chemical action, or by both acting 

 jointly. Nor is it of critical importance whether the precipitated 

 particles were liquid or solid. It is highly probable that the 

 earliest precipitates were formed of material such as later became 

 the stony and metallic substances of the earth, of meteorites, and 

 probably of all the small solid bodies. That such precipitates had 

 begun to form even earlier is highly probable, for they are appar- 

 ently now forming in the sun; at least the solar photosphere is 

 commonly interpreted as a cloudlike zone of such precipitates. 



At the outset such precipitates would necessarily be minute and 

 diffusely scattered, for under the law of diffusion of gases the par- 

 ticular molecules that were precipitable at the temperatures exist- 

 ent at that particular stage would be distributed sub-uniformly 

 throughout the turbulent mixture of molecules which formed the 

 gaseous mass, but aggregation into granules, chondrules,^ or other 

 forms of concretions would doubtless at once ensue, after the 

 analogy of the droplets and crystals of clouds. 



' I venture to name chondrules here to suggest that conditions such as these are 

 perhaps those most likely to have given rise to these singular little aggregates found in 

 the majority of meteorites. They are commonly of the size of a millet seed, but range 

 up to that of a walnut and down to dustlike fineness. 



