■272 



♦ KNO^A^LElDGE ♦ 



[July 1, 1886. 



the whole surface of the globe, and finds that, if produced 

 by the kaolinisation of orthoclase. it must have used up a 

 quantity of carbonic acid equal to twenty-one times the 

 entire weight of our atmosphere, i.e. 2000 X 21 = -12000 

 times as much carbonic acid as the air now contains. The 

 demand for this gas in the decay of such silicates as horn- 

 blende, pyroxene, and olivine is five times as great ; therefore 

 such a stratum produced from these would have used up 

 210,000 times as much carbonic acid as our atmosphere 

 now contains. 



But this is not all, nor nearly all. If the earth were 

 ever in the heated condition usually supposed, no such 

 carbonates as our magnesian and limestone rocks, nor other 

 earthy carbonates from which they might be formed, could 

 have existed ; the lime, the mngnesia, &c., must either have 

 lieen in the caustic condition or combined with silica, most 

 probably the latter. 



The demonstrable chemical conditions necessary for the 

 existence of such carbonates forc3 upon us one of two 

 alternatives. We must either abandon altogether the theory 

 of a highly heated globe that has cooled down, or regard all 

 the carbonic acid existing in our limestones, itc, as of atmos- 

 pheric origin — as a constituent which they have obtained 

 from the atmosphere subsequent to their cooling down. 



The carbonates in tlie earth's crust have been estimated 

 as equivalent " to a continuous layer of limestone 86'J metres 

 (2,851 feet) thick, and probably to more than double this 

 amount." (Sterry Hunt.) According to this the earth 

 contains in this form an amount of carbonic acid equal in 

 weight to 100, if not to 200 atmospheres hke the present, 

 or 200,000 to 400,000 times the amount of carbonic acid 

 now exi-sting in the atmosphere. 



Adding all these quantities together, we reach an amount 

 of carbonic acid of atmospheric origin which utterly con- 

 founds all the prevailing notions concerning the past history 

 of our globe in its relations to its atmosphere. Dr. Thomas 

 Sterry Hunt, who is a philosojjhical chemist and geologist, 

 one who is not satisfied with merely repeating the lessons 

 he has learned at college and adding to them the mechanical 

 results of laboratory and field work, has treated this subject 

 with his customary vigour and originality in a paper com- 

 municated to the Americ'in Jounial of Science, vol. xix.. 

 May 1880, on "The Chemical and Geological Relations of 

 the Atmosphere;" also in another paper in the same journal, 

 vol. xxiii., February 1882, on " Celestial Chemistry from 

 the time of Newton ; " and in the preface to his volume 

 of " Chemical and Geological Essays," published by the 

 Naturalist's Agency of Salem. I strongly recommend the 

 study of these papers to all who are interested in this sub- 

 ject. A summary of them will be found in the abstract of 

 a memoir presented by their author to the British Associa- 

 tion at Dublin, 1878, which is printed in their "Proceed- 

 ings," and also in Nature for August 29, 1878. 



The solution which he offers is the following, quoted from 

 p. 3.!)<5 of t\\e A inericnn Journal of .Science, May 1880: — 

 " The problem still before us is, then, to find the source of 

 the vast amount of carbonic dioxide continuously supplied 

 to the atmosphere throughout the geologic ages, and as con- 

 tinuously removed therefrom, and fixed in the form of car- 

 bonaceous matters and limestones. We have shown reasons 

 for rejecting the theory which would derive the supply either 

 from the earth's interior or from its own primal atmosphere, 

 and must therefore look for it to an extra-terrestrial source. 

 The new h3'pothesis, which we here advance, starts with the 

 assumption that our atmosphere is not primarily terrestrial 

 but cosmical, and that the air, together with the water 

 surrounding our earth (whether in a liquid or a vaporous 

 state), belongs to a continuous elastic medium, which, ex- 

 tending through the interstellar spaces, is condensed around 



attracting bodies in amounts proportional to their mass and 

 temperature. This universal atmosphere (if the expression 

 may be permitted) would then exist in its most attenuated 

 form in the regions farthest distant from these centres of 

 attraction; while any change in the gaseous envelope of any 

 globe, whether by the absorption or condensation, or by the 

 dis ngagement of any gas or vapour would, by the laws of 

 diflusion and static equilibrium, be felt everywhere through- 

 out the universe." 



Those who have read my, essa}' on " The Fuel of the Sun" 

 (January 1870) know that I arrived by a different path to 

 the same conclusion as Dr. H\int concerning the universal 

 diff'usion of atmospheiic matter. I regard such difl'usion 

 into all space which is receiving radiant heat as a necessary 

 and demonstrable operation of the firmly established laws of 

 gaseous difi"usion. 



The revelations of the spectroscope suggest a further 

 development of this hypothesis. The characteristic feature 

 of the spectrum of comets is the pair of bright lines a little 

 way beyond H in the ultra-violet region, which correspond 

 to those obtained artificially from hydrocarbons, such as 

 olefiant gas, <tc. Similar lines have been observed in the 

 trail of meteors that have penetrated our atmosphere. The 

 researches of Schiaparelli and others have shown an inti- 

 mate connection between these meteors and comets. 



In the Gentleman's ilarjazine of August 1881 I ventured 

 t9 put these facts together, and to suggest that " comets 

 and fiery meteors, instead of being the weapons of divine 

 vengeance, wielded for the destruction of the world, liave 

 been beneficent contributors of the chief material of its 

 animal and vegetable life " — my supposition being that 

 there is diff"used through the usually assumed vacuity of 

 space (or at least in that portion through which our 

 solar system travels) considerable quantities of matter 

 having the nature of volati'e hydrocarbons, such as parafiin, 

 naphthalin, benzole, itc. — most probably parafiin — which 

 exist, according to temperature, either as solid, liquid, or 

 gas; and which, .striking our atmosphere in the form of 

 solid particles, are heated and burnt b}' the collision, thereby 

 producing both water and carbonic acid, which would thus 

 be gradually and perpetually introduced. 



At the Southampton meeting of the British Association 

 (1882) Captain Abuey read a paper, in which he stated that 

 he had found benzine and ethyl "indicated in the spectrum 

 at sea level, and found their absorption lines with undi- 

 minished intensity at 8,.'i00 feet. Thus, without doubt, 

 hydrocarlions must exist between our atmosphere and the 

 sun, and it may be in space." [Nature, October 12, 1882, 

 p. 586.) 



GALILEO, DARWIN, AND THE POPE 



By Richard A. Proctor. 



ETWEEN Mr. Mivart, a Catholic believer 

 in the evolution of man from lower 

 forms of animal life, and the Rev. J. 

 IMurphy, Catholic theologian, a contro- 

 ver.sy has arisen which well deserves to 

 be noted, because it serves to indicate 



the precise attitude of the Catholic 



Church towards the doctrine of evolution 

 and science generally. 



On the one hand, Mr. ^Mivart has maintained that he, as 

 a Catholic, is free to teach that man, so far as his body is 

 concerned, has been developed from lower types of life. On 

 the other, Mr. Murphy asserts, as do most Catholic theo- 

 logians, that this doctrine is heretical, and cannot be main^ 

 tained by any loyal Catholic. Mr. Mivart retorts that the 



