ANALYSES OF GYPSEOUS EARTH. 473 



* Carbonate of lime 2.350 



Bi-sulpliuret of iron 5.821 



Sulphate of lime 2.309 



(Carbonate of magnesia not found.) 



" ' No. 10. Several tliin layers of compressed shells, 1 to 3 inches thick" 

 [contained in stratum E.~\ 



Carbonate of lime 56.00 



Phosphate of lime 0.84 



"No. 2. [Z>] from 4 feet lower than number 1, was examined with results 

 similar to 1 and 3. 



" No. 4. [Z>] from 4 feet below beach, and half a mile from number 1, was 

 found to be rich in sulphate of lime and to contain bi-sulphuret of iron. 



"No. 5. [Z>] ' From another spot, and has since been exposed to the 

 weather from last winter to June on the field where applied as manure.' 

 Is richer than No. 2 or 4 in sulphate of lime, but inferior to either in bi- 

 sulphuret of iron. It likewise affords more sulphate of alumina than any- 

 sample examined. 



" 'No. 11. The clay at 16 to 18 feet deep ;' [supposed when selected to 

 be the poorest part of stratum E.~\ 



Carbonat* of lime 1.45 



"It is rich in sulphate of lime, and has traces of sulphate of alumina, 

 and bi-sulphuret of iron. 



" It is to be kept in mind that in these analyses no account is taken of 

 such sized crystals of sulphate of lime as readily meet the eye, or of large 

 fragments of shells, the occasional presence of both which must often 

 essentially enhance the gypseous and calcareous contents of these samples. 

 The proportions in which they may occur at different depths and localities 

 can readily be determined, however, by the practical agriculturist. The 

 same may be said of the phosphatic ingredient so far as the teeth and 

 bones of fishes are concerned. 



If we assume the average proportion of bi-sulphuret of iron in these 

 earths to be 2 per cent., and suppose the whole of the sulphate to become 

 oxydized, it would give rise to 2.722 per cent, of sulphuric acid ; to saturate 

 which would require 1.905 of lime, and thereby produce 4.627 per cent, 

 of (anhydrous) sulphate of lime. But 2.722 of lime would demand 3.883 

 per cent, of carbonate of lime in the soil. Now in the three analyses (Nos. 

 3, 6, and 9), made, the bi-sulphuret of iron, by average, equals 3.649 per 

 cent., and the carbonate of lime in the same equals but 1.478 per cent. 

 a quantity too small for the saturation of the acid, even after a liberal 

 allowance is made for the increase of calcareous matter from the occasional 

 presence of large fragments of shells. 



"It would therefore appear to be an obvious deduction from these inqui- 

 ries, that dressings of lime, and especially of calcareous bands, like No. 

 10, should be employed in conjunction with the green-sand soil. 



" Having now replied in the best way I am able to your various inquiries, 

 I leave it for you to make such other practical inferences from the inform- 

 ation afforded as in your more experienced judgment it may seem to 

 authorize and remain, very respectfully, your obedient servant, 



CHARLES UPIIAM SIIEPARD." 

 "EDMUND RUFFIN, Esq." 



The specimens numbered above 1, 2, 3, were from one locality, 



and of earth which was used as manure for clover of this year, 



on marled land, with effect as great as any ever known ; and with 



no certain benefit on an adjoining space (also in clover), of the 



40* 



