14 



Those coming frcm the Chazy formation at Alumette Island, left 

 after calcination 6i% of fixed residue, consisting of : 



Phosph.ite of lime 85 7 



Carbonate of lime 11 7 



Magnesia 2 6 



100 o 

 and analysis of the original uKitciial gave as follows : — 



Alumette. Hawkesbury. R. Quelle. 



Phosphate of lime 36-38 44 ■ 70 40 . 34 



Carbonate of lime and some fluorine ... . 5.00 6.60 5 -14 



Carbonate of Magnesia 4-76 9 • 7° 



Oxide of Iron and Alumina 7.02 8.60 12.62 



Magnesia 



Insoluble 49 ■ 9c 27 . 90 25 . 44 



Volatile by heat 1.70 5 • 00 2.13 



100.00 97.56 95.37 



We here observe an average of 40% of phosphate of lime. It 

 would appear that our knowledge of the proportion of phosphatic 

 element in similiar animal remains is very imperfect, so that upon 

 further investigations, we may expect to meet with many other similar 

 accumulated supplies of phosphoric acid. 



Some authorities attribute a large portion of the phosphate of lime 

 in the Charleston fields to such molluscs and principally Lingula 

 pyramidata, which are found abundantly on the present coast. 



CLASSIFICATION OF NATURAL PHOSPHATES. 



I prefer for all practical purposes and from rational observation 

 to modify the classification proposed by Dr. Penrose, thus : — 



. .^ ) Fluor-Apatites. 



AP^^'^^^ I Chlor-Apatites. 



] Phosphorites. 

 I Nodules, Coprolites. 

 I Concretions. 

 Mineral and Rock Phosphates }- Conglomerates. 



Phosphatic Limestone. 



Phosphatic Marls. 



Crust Guanos. 



