1887.] on Genesis of the Elements. 51 



But how can we suppose tbe protyle, or fire-mist, converted into 

 the atomic condition ? In amorphous matter we recognise a tendency 

 to aggregation not to be identified with gravitation, since it is mani- 

 fested among finely-divided matter, whether suspended in a medium 

 of a si^ecific gravity superior, equal, or inferior to its own. This 

 agglutinative action is familiar to observers of natural phenomena. 

 Clouds contracting to that appearance known as a mackerel sky ; 

 particles of carbon floating in the air, collecting, and ultimately 

 falling as " blacks " ; chemical precipitates, at first finely amorphous, 

 but gradually becoming flocky, granular, and crystalline ; vortex 

 rings, suddenly quickening out of amorphous smoke;— all these, and 

 many more, exemplify that universal formative principle in nature 

 which I suggest first made itself manifest in the condensation of 

 protyle into atomic matter. 



A few weeks ago, in this theatre, Sir William Thomson asked you 

 to travel back with him an imaginary excursion of about twenty 

 million years. He pictured to you the moment immediately before 

 the birth of our sun, when the Lucretian atoms rushed from all parts 

 of space with velocities due to mutual gravitation, and, clashing 

 together, formed in a few hours an incandescent fluid mass, the 

 nucleus of a solar system with thirty million years of life in it. I 

 will ask you to accompany me to a period even more remote, — to the 

 very beginnings of time, before even the chemical atoms had con- 

 solidated from the original protijU. Let us imagine that at this 

 primal stage all was in an ultra-gaseous state — a state difi'ering from 

 anything we can now conceive in the visible universe. 



Now unless the expression " fire-mist " and the supj)Osition that 

 pristine matter was once in an intensely heated condition * are quite 

 misleading and baseless, we have to deal with a process analogous to 

 cooling. This operation, probably internal, reduces the temperature 

 of the cosmic protyle to a point at which the first step in granulation 

 takes place ; matter as we know it comes into existence, and atoms 

 are formed. As soon as an atom is formed out of protyle it is a store 

 of energy, kinetic (from its internal motions), and potential (from its 

 tendency to coalesce with other atoms by gravitation or chemically). 

 To obtain this energy the neighbouring protyle must be laid under 

 contribution, i, e. must be refrigerated by it, thereby accelerating the 

 subsequent formation of other atoms. With the birth of gravitating 



Prima," or matter undifferentiated into elements, without form, in fact, and 

 consequently ayvoiaros, unknown and unknowable, and (2) ia-xarr] v\t]. secondary 

 or formed matter, such as earth, or metal, or water, or any other raw material 

 with which we are familiar. 



* I am constrained to use words expressive of high temperature; but I 

 confess I am unable clearly to associate with protyle the idea of hot or cold. 

 Temjyerature, radiation, and free cooling seem to require the periodic motions that 

 take place in the chemical atoms; and the introduction of centres of periodic 

 motion into protyle would involve its being so far changed into chemical atoms. 

 Probably the first operation was more analogous to the formation of vortex rings 

 than to a reduction of temperature. 



E 2 



