AND THE PHOSPHATIC BEDS NEAR MONS. 335 



Between the villages of St. Symphorien and Havre the rich 

 phosphate is met with below the level of the underground water. 

 The substance here has a greenish-blue tint, very different from that 

 of the rich phosphate of Mesvin, Ciply, &c. Its chemical composition 

 has been determined as follows by Professor Bias of Louvain * : — 



Dried substance preserved in the air of the laboratory'. 



1. Water at 115° C 060 



2. Organic matter 2-67 



3. Iron oxide 207 



4. Alumina 1*72 



5. Lime 38-52 



6. Magnesia 0*40 



7. Potash 003 



8. Soda 1-47 



9. Phosphoric acid 25'85 



10. Sulphuric acid 4*05 



11. Carbonic acid 5'40 



12. Silica •. 14-00 



13. Chlorine 0*15 



14. Fluorine 2-38 



15. Impurities in the Silica 060 



Deduct :— 



For an equivalent of fluorine and an "j 



equivalent of oxygen 100 1 103 



For an equivalent of chlorine 0-03; 



Balance 98-88 



Manganese and other bodies not determined 1*12 



10000 



M. Bias found traces of iodine in the residue. 



According to the two analyses which I have just given, there 

 are notable differences between the rich reddish-yellow phosphate of 

 Mesvin and the rich greenish-blue phosphate of Havre. The latter 

 contains less organic matter than the former, but more insoluble 

 substances and more fluorine. These differences are probably due 

 to various causes, which I will not enter upon here. I mil only 

 remark that the rich phosphate of Mesvin, analyzed by M. Peterman, 

 was derived from a deposit resting upon the brown chalk without 

 flints, d' ; whilst that at Havre, the rich phosphate of which M. Bias 

 has given the composition, was superimposed upon the brown chalk 

 with flints, d^. 



The extraction of the rich phosphate was commenced in 1879, on 

 the land of the Commune of Mesvin. Since then the workings have 

 been successively extended to Ciply, St. Symphorien, Havre, Nou- 

 velles, and Cuesmes, that is to say nearly everywhere that the Brown 

 Phosphatic Chalk is not covered by the Tufaceous Chalk. 



It is at Mesvin, Ciply, and Cuesmes that the beds most remarkable 

 for their thickness have been found. Pig. 5 gives the exact repre- 



* Bull, de I'Acad. Royale de Belgique, 3^ ser, vol. viii. 



