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L. On the Chemical Composition of Recent and Fossil Lingulse, 

 and some other Shells. By W. E. Logan, F.R.S., and T. S. 

 Hunt*. 



IN the Report of Progress of the Geological Survey of Canada 

 for 1851-52, we have mentioned the existence of small 

 masses containing phosphate of lime, and having the characters 

 of coprolites, which occur in several parts of the Lower Silurian 

 rocks. In a bed of siliceous conglomerate towards the top of 

 the calciferous sandstone, at the Lac des AUumettes, on the 

 Ottawa, they are abundant in cylindrical and imitative shapes, 

 sometimes an inch in diameter. The same material foi-ms casts 

 of the interior of a species of Holopea or Pleurotomaria, and 

 often fills or completely encases the separated valves of a large 

 species of Lingula, which Salter has referred to L. jiarallela of 

 Phillips. The phosphatic matter is porous, friable, and of a 

 chocolate-brown colour ; it contains intermixed a large quantity 

 of sand, and small pebbles of quartz are sometimes partly im- 

 bedded in it. The analysis of one specimen gave 36 per cent, of 

 phosphate of lime, with 5 per cent, of carbonate and fluoride, 

 besides some magnesia and oxide of iron, and 50 per cent, of 

 siliceous sand. 



Similar masses occur in the same formation at Grenville, and 

 in the lower part of the Chazy limestone at Hawkesbury, in both 

 cases containing fragments of Lingula. Those from the latter 

 place are rounded in shape, and from one-fourth to one-half of 

 an inch in diameter, blackish without, but yellowish-brown 

 within, and having an earthy fracture ; the analysis of one of 

 them gave : — 



Phosphate of lime (PO^, 3CaO) . . . 44-70 



Carbonate of lime 6*60 



Carbonate of magnesia 4*76 



Peroxide of iron and a trace of alumina . 8'60 



Insoluble siliceous residue 27*90 



Volatile matter . 5'00 



97-56 



From the colour it is probable that the iron exists as a car- 

 bonate. When heated in a tube, a strong odour like burning 

 horn is perceived, accompanied by ammonia which reddens tui'- 

 meric paper and gives white fumes with acetic acid, showing 

 that a part at least of the volatile matter is of an animal nature. 

 The specimens from Lac des AUumettes lose 1'7 per cent, by 

 gentle ignition, with a like production of ammonia, and an odour 



* From Silliman's American Journal, vol. xvii. p. 235. 



