ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxxiii 



Mr. Nesbit has also commnnicated to us some remarks on the 

 presence of phosphoric acid in the subordinate members of the cre- 

 taceous series. He states that he mentioned to INIr. Paine, in No- 

 vember 1847, the existence of a large amount of phosphoric acid in 

 a fertile Farnham marl, and that he subsequently obtained 28 per 

 cent, of phosphoric acid from portions of this marl, the general mass 

 containing about 2 per cent. Nodules from the Maidstone gault also 

 gave him 28 per cent, of phosphoric acid. Other localities are no- 

 ticed, and as much as 69 per cent, of phosphoric acid is mentioned 

 as contained in a dark red sandstone rock occurring in masses in the 

 upper portion of the lower greensand at Hind Hill. 



Mr. Wiggins has sent us a notice of the fossil bones and coprolitic 

 substances discovered in the crag of Suffolk, remarking on the value 

 of the latter for agricultural purposes, 200 tons of them having been 

 obtained from about a rood of ground, — an additional instance of the 

 remains of animals and their fseces entombed in rocks of different 

 geological ages becoming available for the growth of existing plants. 



As regards phosphate of lime and its dissemination, which modern 

 researches have shown is much greater, when sufficient quantities of 

 rocks are examined, than appeared from the analyses of the small 

 portions usually employed, — a matter of interest when we consider 

 the phosphate of lime required for certain plants, — we should recollect 

 that when free carbonic acid is present in water, the phosphate, like 

 carbonate of lime, though not to the same amount, is very soluble. 

 Hence, especially when, as noticed by Mr. Austen, phosphate of lime 

 is disseminated in the state of fresh coprolites amid detrital matter, 

 and water containing free carbonic acid is present and can have access 

 to it, the phosphate of lime would be in a condition to be removed 

 and disseminated. Mr. Austen has alluded to the mixture of such 

 bodies with vegetable matter, to the decomposition of which, with 

 animal matter also, we might look for some, at least, of the carbonic 

 acid that would aid the solution of the phosphate of lime. As in the 

 case of the carbonate of lime previously noticed, when the solution of 

 this phosphate met with the silicates of potash or soda, whilst perco- 

 lating amid the rocks, the silicates would be decomposed by the car- 

 bonic acid, and the phosphate of lime thrown down. We should 

 expect, — in the same manner as carbonate of lime often replaces the 

 original matter of a shell which has been decomposed and removed 

 from the body of a rock, leaving those cavities commonly termed 

 casts, — that phosphate of lime, in localities where from accidental 

 circumstances it was somewhat abundantly filtering through rocks, 

 would also enter these and any other cavities, filling them under the 

 needful conditions of deposit. In like manner as we find carbonate of 

 lime separating itself from mud and silt in which it was disseminated, 

 forming the nodules so common in calcareo-argillaceous deposits, 

 should we also expect disseminated phosphates of lime to do the 

 same under fitting conditions ; so that it would not necessarily fol- 

 low, however true in numerous cases, that nodules containing much 

 phosphate of lime were coprolitic. We can readily imagine circum- 

 stances very favourable for the solution and spread of these phosphates 



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