SCIENCE- GOSSIP. 



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ioo° C. , but for silicon it is at a far higher tempera- 

 ture. We may call this range of temperature the 

 transitional range of the element, inasmuch as these 

 complexes are incapable of existing above this range, 

 •while below it they become stable. 



Now, it is clear that, in consequence of the pro- 

 gressive cooling of the earth, the transitional range 

 of silicon would soon be passed, and hence its com- 

 plexes would solidify into stable masses, thus causing 

 all life to cease. Hence, if the carbon entered more 

 and more fully into the composition of living matter, 

 and the silicon as steadily solidified out as the cooling 

 continued, the transitional temperature (or tempera- 

 ture of continual decomposition) of living matter 

 would become progressively lower in proportion as 

 the amount of carbon in the organism increased, and 

 hence the cooling of the surrounding medium, and 

 the alteration in the living temperature of the 

 organism, would proceed together and keep pace. 

 The Silicon Age would thus blend imperceptibly into 

 the Carbon Age, and when the modern thermal con- 

 ditions were attained, the carbon would have long 

 since completely replaced the silicon in the living 

 matter, and the last era of organic existence would 

 have been entered upon. I would, however, call 

 attention to the fact that among some of the most 

 rudimentary forms of organised existence, for example 

 the diatoms and sponges, silica still remains. This 

 might possibly be a case where the replacement of 

 silicon by carbon is not yet quite complete. 



It is therefore probable that, as the thermal con- 

 dition of the earth altered, there was a corresponding 

 alteration in the composition of living matter, the 

 denser and less volatile elements, such as silicon, 

 steadily solidifying out, and their places being filled by 

 lighter and more volatile elements. But this replace- 

 ment of denser by lighter elements is now almost 

 complete, for the principal elements already present 

 in organic matter are carbon, nitrogen, oxygen, and 

 hydrogen : and these, it will be noticed, are the very 

 lightest chemically active non-metallic elements. No 

 lighter elements, then, can replace those already 

 present in the organism, and therefore there can be no 

 further great alteration in the temperature of living 

 matter in the coming ages ; but the world is still 

 cooling, while the temperature of living matter is re- 

 maining almost constant. There is, even now, 

 evidence that the mean temperature of the earth's 

 surface is already approaching the limit of the transi- 

 tional range of carbon. 



Age by age, century by century, the contrast 

 between the temperature of organic matter and the 

 temperature of the surrounding medium is becoming 

 more and more accentuated, and the difficulty of 

 maintaining life is steadily increasing ; indeed, life 

 now flourishes on a far less luxuriant scale than 

 formerly ; the giant vegetation and huge monsters of 

 the past are gone, and in their place is a dwarfed 

 creation, better able to maintain the vital tempera- 

 ture on account of the smaller surface area. 



At the period we are considering the earth was 



one great sea of molten fluid. The huge volume of 

 water that now stretches from continent to continent 

 and girdles the globe was then largely in a state of 

 vapour, and together with vast quantities of other 

 gases must have exerted an enormous pressure upon 

 the molten surface : huge quantities of liquid must 

 have been ever condensing in the upper regions and 

 continually pouring upon the white-hot sea, only to be 

 hurled aloft again, mingled with molten dibris, in a 

 series of vast explosions. 



Who can say what strange combinations and solu- 

 tions occurred at these high temperatures and enor- 

 mous pressures ? It is well known that under such 

 conditions the solubility of substances in each other 

 increases indefinitely. Most salts at their melting- 

 points become miscible with water in all proportions ; 

 glass and many of the most insoluble bodies become 

 freely soluble when heated highly, under enormous pres- 

 sures with water, but again separate out on releasing 

 the pressure or on lowering the temperature. The vast 

 masses of rolling vapour and liquid that drove in huge 

 waves across that blazing sea must then have been 

 very complex mixtures, and in such life could well 

 generate and maintain itself. Even when the tem- 

 perature fell to such an extent that the rocks sepa- 

 rated out in solid masses, the thick boiling fluid that 

 remained must have differed widely in composition 

 from the ocean of to-day, and must have held in gela- 

 tinous solution tile most various substances, for the 

 pressures would still be enormous and the temperature 

 still high. 



Such fluids as these, then, probably served as the 

 medium wherein life flourished during the slow 

 passage from the Silicon to the Carbon Age, and in 

 such fluids was effected the gradual displacement in 

 the organism of the silicon by the carbon. 



Mcndeleef divides the elements into a number of 

 scries, according to the magnitude of their atomic 

 weights. Xow those elements of the first and second 

 series, which occur in matter living al ordinary tem- 

 peratures—viz. hydrogen, carbon, nitrogen, and 

 oxygen — would be too volatile to occur in matter 

 living at, say, a white heal. Consequently they 

 would probably be replaced by the analogous heavier 

 and less volatile elements of the series below them : 

 for example, instead of carbon, nitrogen, oxygen, 

 and hydrogen, we should get silicon, phosphorus, 

 sulphur, and. say. oxygen in the organism. To every 

 series of elements, right up the scale, there should 

 correspond a stage of life existing al a corresponding 

 stage of temperature. 



It appears from a short note that occurred in 

 "Nature" (March 8th) on my article in SciENCE- 

 GOSSIP that Dr. F. J. Allen regards nitrogen as the 

 central element in ordinary living matter ; whereas, 

 in my opinion, it is carbon. I am perfectly willing 

 to admit that nitrogen is absolutely essential to the 

 maintenance of life, because it probably causes the 

 state of dynamical equilibrium that is supposed to 

 exist in living organic matter. It is well known that 

 the phenomenon of Tautomerism (Laar) is exhibited 



