APPENDIX I. 



THE CHEMISTRY OF THE PRHIITIVE OCEAN. 



A. B. Macallum^, in an extremely interesting paper, discusses this 

 question from the point of view of the composition of the blood and 

 tissue-fluids of marine and land animals. Originally the earth was a 

 molten mass, and the temperature was so high that many compounds 

 now in the solid state were then in the form of vapour, and with 

 their elements dissociated from each other, as is still tlie case in the 

 atmosphere of the sun. But as the earth cooled down, and as the 

 crust became solid, the temperature of the atmosphere fell, and then 

 many of these elements combined together to form compounds, such as 

 chlorides, sulphates, carbonates and oxides of sodium, potassium, 

 magnesium, calcium and others, and these compounds were pre- 

 cipitated on the thin, solid, but still very hot crust of the earth. 

 The temperatures at which these combinations and precipitations took 

 place were very variable and depended on the pressure of the atmo- 

 sphere, which was then much greater than it is at present, but was 

 continually falling. Probably when these compounds were first 

 condensed, refusion of the thin crust of the earth would take place 

 over the areas of precipitation and thus diffusion of the salts would 

 take place over considerable areas of the crust. Solidification and 

 refusion would probably take place many times before a permanently 

 solid crust could be formed. When the temperature of the latter fell 

 low enough the water vapour of the atmosphere would also be pre- 

 cipitated, but it would again be evaporated ; and these condensations 

 and revolatilisations must have taken place very many times before 

 the first permanent seas would be formed. There would be places 

 on the earth where the temperature of the crust was lower than 



^ "The Palaeochemistry of the Ocean," Trans. Canadian Institute, vol. vii. 

 1904. 



