NO. 6 • AGE OF TTTE EARTH — BECKEK 7 



the normal chlorine. Inqniiy of Mrs. Ellen S. Richards as to the chlorine 

 of the rainfall in" Massachusetts confirmed this view. The assumed rela- 

 tion leads at once to the amount of wind-borne sodium along a length of 

 coast of about 500 miles ; and supposing the total length of the coast of 

 the United States (without counting indentations) to be 4,500 miles, the 

 order of magnitude of the correction required is 6 per cent. Mr. Clarke 

 from different data and by a different course of reasoning estimates this 

 correction at 7 per cent. 



Applying a 6 per cent, correction reduces the annual river-borne sodium 

 of the world an eighty-six millionth part of the oceanic sodium, or to 

 164.5 X 10® tons, of which more than half is combined with chlorine. 



The origin of oceanic chlorine has long been regarded as mysterious. 

 Average rock contains less than 2 per cent, of the chlorine needed to con- 

 vert the accompanying sodium into chloride, and this has led to hypo- 

 tlieses of a primitive atmosphere heavily charged with chlorine or to an 

 original solid surface containing great quantities of ferrous chloride. It 

 may still be needful to seek such explanations, yet they seem to me highly 

 unsatisfactory. From the base of the Cambrian onward some animal 

 forms, such as Lingula, have persisted practically without change, and 

 there is ever}^ paleontological indication that Paleozoic sea-water was a 

 medium substantially like that of to-day. Had the sea been overcharged 

 with chlorine in any form, consequences of this fact would almost cer- 

 tainly have manifested themselves in the composition of sediments and the 

 decomposition of rocks, but nothing known to me indicates any unfamiliar 

 chemical conditions. In the absence of sucli proofs it seems unreasonable 

 to assume a Cambrian ocean essentially different from that of to-day. 

 Now the ordinary geological estimate of the age of Cambrian strata is 

 something like 30 million years; and during that period some 30 million 

 times 63 million tons of unchloridized sodium, or perhaps considerably 

 more than this, has been poured into the sea. All of this sodium has 

 found chlorine to saturate it, once and a half its own weight of chlorine. 

 Where can all this have come from ? 



We all know definitely that volcanoes and solfataras emit free chlorine, 

 chlorhydric acid, ammonium chloride, calcium chloride and sodium 

 chloride. Hot springs and certain cold springs also emit some of these, 

 especially calcium chloride. So abundant is chlorhydric acid in the 

 emanations of Vesuvius that according to Mr. Suess ' vegetation has been 

 blasted over large areas by acid rain, and according to Mr. Stoklasa "" the 

 greater part of the " pine-tree " clouds above the crater of Vesuvius dur- 

 ing eruptions consists of chlorides, mainly ammonium chloride. Other 

 volcanoes send out similar emanations and since there are hundreds of 



1 Ueber heisse Quellen: Verhandl. Gesell. deutsch. Naturf. und Aerzte, 1P02, p. 113. 

 "Ber. Deutsch. chem. Gesell., vol. 39, 1906, p. 3530. 



