THE CHEMICAL EXAMINATION OF THE MATERIALS FliOM FUNAFUTI. ;?71 



6, Proporteon of Phosphates in the Materials from Funafuti. 



The early analyses of corals and other marine calcareous organisms made by 

 Hatchett* and Benjamin Silliman, JuNR.,t showed that besides the calcium and 

 magnesium carbonates, various other substances were present in small quantities ; 

 in addition to silicon, aluminium and iron, corals have been found to contain both 

 phosphorus and fluorine. 



Of the other salts combined with the carbonates of the corals, the phosphates appear 

 to be the most ubiquitous and important. Silliman found minute quantities of 

 phosphoric acid in nearly all the corals which he analysed. Sharples in his analyses 

 carried on the laboratory of Professor Brush, in the Sheffield Scientific School, Yale 

 University, found much larger amounts of phosphoric acid. He arrived at the 

 conclusion that corals contain from 0'3 to 0"8 of calcium phosphate,| while a rock 

 composed of coral fragments dredged by Count Pourtales from the ocean beneath 

 the Gulf Stream between Cuba and Florida, yielded 1'20 of calcium phosphate. As 

 we shall see in the sequel, the amount of phosphoric acid found by Sharples in corals 

 and in coral-rock, is much in excess of what other analysts have obtained, and it seems 

 probable that there was some source of error in the chemical methods employed 

 by the analyst, or else that his specimens were of somewhat exceptional character. 

 Sharples, indeed, argues as the result of his studies, that the proportion of phosphates 

 may undergo an increase in materials of this kind as they lie on the ocean-floor. 



Liversidge,§ Cooksey,|| Pollard,1F Stbiger,** HARRisoNft and other chemists have 

 only detected minute traces of phosphates either in corals or coral-rocks ; and the 

 preliminary qualitative analysis of the Funafuti rocks showed phosphates to be present 

 only in very minute quantities. In order that the question of the proportion of 

 phosphates in the rocks from the Main Boring at Funafuti should be placed beyond 

 doubt, I requested Dr. Cullis and Dr. Skeats to determine the amount of those salts 

 in some of the cores which showed unmistakable evidence of their presence. The 

 determination of the phosphates was made in the same way as in the earlier analyses 

 (see p. 362), by their precipitation as ammonium phospho-molybdate. 



The results obtained are given on the following page, the proportions of calcium 

 phosphates at the several depths being stated : — 



* ' Phil. Trans.,' vol. 90 (1800), p. 327. 



t 'Amer. Joiirn. Sci.,' 2nd series, vol. 1 (1846), p. 189; 'United States Exploring Expedition' 

 (Zoophytes), 1846, p. 712. 



I ' Amer. Journ. Sci.,' 3rd series, vol. 1 (1871), p. 168. 



§ ' Journ. Proc. Eoy. Soc, New South Wales,' vol. 14, pp. 159-162. 



II Memoir III., Austral. Museum, Sydney. ' The Atoll of Funafuti,' Part 1, p. 76. 

 H ' Proc. Camb. Phil. Soc.,' vol. 9, p. 417. 



** 'Bull. Harvard Coll. Mus.,' vol. 26(1895-6), p. 85. 

 ft 'Quart. Journ. Geol. Soc.,' vol. 47 (1891), pp. 197-245. 



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