28 



Carbonate of lime, 95.18 grs. 



Phosphate of lime, 1.88 



Silcx (probably accidental,) 0.40 

 Water, 1.62 



Insoluble animal matter, 0.45 



Loss, &c. 0.45 



100.00 

 [Vide Farmer's Register, Vol \,and Silliman's Journal. 



These remarks being also applicable to some species of fossil 

 shells, it becomes necessary to a judicious selection of the marl, to 

 give some attention to the different nature of the shells contained in 

 the several varieties of marls offered to our choice. 



KINDS OF SHELLS WHICH ARE LEAST LIKELY TO BE USEFUL. 



The Fossil oyster and Scallop shells, (Ostrea Virginica and Pec- 

 ten,) of which many marl beds are almost exclusively composed, are 

 generally found in a nearly unaltered state. Comparing the compo- 

 sition of these shells, as ascertained by my analysis, with that of the 

 recent shells, the animal matter which, though small in quantity, 

 seems to act powerfully as a cement for the other materials, was 

 found to have been retained in almost undiminished proportion ; and 

 thus these shells are scarcely better fitted for the soil, than recent 

 ones of the same species. It is to the animal matter retained by the 

 fossil scallops that we are to ascribe the dark colour which they as- 

 sume when burnt for lime. Whatever might be the usefulness of 

 this ingredient if mingled with the soil, it here operates to impair the 

 value of the shell as calcareous manure by the insoluble character it 

 imparts to the materials it holds together. Next in tardiness of dis- 

 integration, and in consequent inefficacy as a manure, may be enu- 

 merated the large clam, (Venus mercenaria,) and an oblong smooth 

 fiat shell, (Crassatella.) These, however, have evidently undergone 

 a change, which prepares them for yielding, more readily than the 

 former, to the agencies of the seasons. Most of the other species, 

 though entire when first found, soon fall to pieces and spread their 

 fertilizing fragments through the soil. There is, however, even 

 among them some room for choice — and this leads us to consider 

 the 



