CALCAREOUS PART NOT PRIZED. 381 



plication of marl as a manure, I inquired -where there was any in the penin- 

 sula of the Chesapeake in vain. My own farm had a grayish clay which to 

 the eye was marl : but because it did not effervesce with acids, it was 

 given up when it ought to have been tried on the land, especially as it ra- 

 pidly crumbled and fell to mud, in water, with some appearance of effer- 

 vescence." Bordley 's Husbandry, 2d ed., p. 55. 



That peninsula, through which Mr. Bordley in vain inquired for 

 marl, has immense quantities of the fossil shells which we impro- 

 perly call by that name. But as his search was directed to marl 

 as described by English authors and not to calcareous earth sim- 

 ply it is not to be wondered at that he, well-read and intelligent 

 as he was, should neither find the former substance, nor attach 

 enough importance to the latter, to induce the slightest remark on 

 its probable use as manure. 



16. The Practical Treatise on Husbandry -, among the directions 

 for improving clay land, has what follows : 



" Sea sand and sea shells are used to great advantage as a manure, 

 chiefly for cold strong [i. e. clay] land, and loam inclining to clay. They 

 separate the parts ; and the salts which are contained in them are a very 

 great improvement to the land. Coral, and such kind of stony plants 

 which grow on the rocks, are filled with salts, which are very beneficial to 

 land. But as these bodies are hard, the improvement is not the first or 

 second year after they are laid on the ground, because they require time to 

 pulverize them, before their salts can mix with the earth to impregnate it. 

 The consequence of this is, that their manure is lasting. Sand, and the 

 smaller kind of sea weeds, will enrich land for six or seven years ; and 

 shells, coral, and other hard bodies, will continue many years longer. 



" In some countries fossil shells have been used with success as manure ; 

 but they are not near so full of salts, as those shells which are taken 

 from the sea-shore ; and therefore the latter are always to be preferred. 

 Sea sand is mxich used as manure in Cornwall. The best is that which is 

 intimately mixed with coral." p. 21. 



After stating the manner in which this " excellent manure" is 

 taken up from the bottom, in barges, its character is thus con- 

 tinued : 



" It [i. e. the sea sand mixed with coral, as it may happen] gives the 

 heat of lime, and the fatness of oil, to the land it is laid upon. Being 

 more solid than shells, it conveys a greater quantity of fermenting earth in 

 equal space. Besides, it does not dissolve in the ground so soon as shells, 

 but decaying more gradually, continues longer to impart its warmth to the 

 juices of the earth." 



Here are described manures which are known to be calcareous, 

 which are strongly recommended but solely for their supposed 

 mechanical effect in separating the parts of close clays, and on ac- 

 count of the salts derived from sea-water, which they contain. 

 Indeed, no allusion is made to any supposed value, or even to the 

 presence of calcareous earth, which forms so large a proportion of 

 these manures ; and the fossil shells (in which that ingredient is 



