20 



chi:mical manures. 



These analyses show that the Meuse and Ardennes nodules are 

 similar in composition to those of Boulonnais and the neighbourhood 

 of Pernes-en-Artois, which is quite natural, both being of the same 

 origin and situated at almost the same geological horizon. 



4. Cote d'Or Phospliates. — As far back as 1822, De Bonnard dis- 

 covered near St. Thibault (Cote d'Or), in a cutting of the Burgundy 

 Canal, greyish-white nodules which contained, according to an 

 analysis by Berthier, 74 per cent of phosphate of lime. These 

 nodules associated with grains of ammonite were impasted in a 

 m.ass of brown clay, but at that period but little importance was 

 attached to the discovery, and it was only in 1872 that CoUenot 

 re-discovered them in excavations made on the plan of the railway 

 from Cravant to Laumes. He collected samples which Georges 

 Ville found to contain 60 to 61 per cent of tribasic phosphate. In 

 1873-1 this formation was examined by Poncin, who immediately 

 profited thereby. It was thus that towards the end of 1876 the 

 phosphate works of Auxois came into being. The horizon exploited 

 belongs to the Lower Lias of Burgundy ; it is situated towards the 

 summit of the gryphesis arquees (? gryphea incurva) limestone 

 zone with Ammonites SteUarls. Towards the top this limestone 

 is rich in soft, almost friable phosphatic nodules, which are enclosed 

 in the marly mass, the whole forming a mixture, the phosphate 

 content of which varies from 30 to 45 per cent. The phosphatic 



