CALCAREOUS MANURES-APPENDIX. 203 



From King William, (Lipscomb's land)— 82 per cent, of carbonate of lime. 

 (Slaughter's land)-88 " 



" New Kent, (Col. Macon's land)— 88 

 Middlesex, (Oaks' land) - 83 



Some of very similar appearance, but still more approaching in texture 

 to a very soft rock, from Lenoir county, N. C, and the bank of Neuse 

 river, contained 75 per cent, of carbonate of lime. Sundry other speci- 

 mens, of still more homogeneous and firm texture, from the banks of the 

 Santee, S. C, contained about 95 per cent. Most of these jnarls are soft 

 enough to be used for manure as dug from the pits ; but the hardest lumps 

 may need burning to lime. Any hard enough to need burning, and as 

 rich as 85 per cent, will make good lime for cement, as well as for manure. 



Under a peculiar combination of circumstances, the great richness of 

 some marls operates to lessen the value of the body as manure. Rain 

 water, when just fallen, always contains some carbonic acid, which admix- 

 ture causes it to be a solvent of carbonate of lime. When rain water then 

 can descend by percolation into rich dry marl, in its passage it dissolves 

 some of the calcareous matter, which is again left solid, and in crystals, by 

 the slow evaporation of the fluid. These crystals of carbonate of lime are 

 slowly added to by every recurrence of the like causes, until the cavities of 

 large shells, and other openings into which the water had settled, are com- 

 pletely filled with crystallization. If layers of marl, less pervious to water 

 than in general, oppose the descent of the water, the crystallization forms 

 in connected horizontal layers, separated by the thicker layers of softer 

 marl. Such crystallized layers are found abundantly in the very rich marl 

 at Yorktown, serving by their stony hardness to impair the otherwise great 

 value of the manure. At Bellfield, Col. Robert McCandlish's farm, a few 

 miles higher on York river, the hollows of large shells have been filled with 

 beautiful and brilliant crystals thus formed. In Surry also, on the land of 

 the late William Jones, such crystallization is abundant. For such effect to 

 be produced, there are several conditions necessary. The superincumbent 

 earth must be of open texture, and not very thick — or rain water could not 

 pass through. It must not be a hill-side — as the water would flow off" the 

 surface and not penetrate to the marl. And the marl must be dry — or eva- 

 poration could not take place, and of course not crystallization. 



Gloucester, though one of the outside marl counties to the east, is most 

 abundantly supplied with marl, accessible on almost every farm, whether 

 of high or of low grounds. It is generally of the poorer yellow kind. 

 But three marked exceptions were seen, which as such deserve to be 

 named. Cne is the rich clay marl forming the north bank of Ware river 

 on the farm of Mr. Alexander Taliaferro. Another is the general sub-soil 

 (as it may considered from its position) of the lowest land of the farm of 

 Mr. Jefferson Sinclair, near the mouth of Severn river. This is an almost 

 pure body of coarse shelly powder, or fragments, seldom found larger 

 than two or three grains in weight, and a very few shells, of as minute size, 

 entire enough to be distinguished. This mass of shelly matter is as loose 

 and incohesive as coarse sand, yet is tinged slightly with green by the ad- 

 mixture of greenish clay. A specimen analyzed contained 72 per cent, 

 of carbonate of lime. (See more full account at page 181, vol. vi. Farmers' 

 Register.) The third is the marl used by Capt. P. E. Tabb, and dug from 

 beneath the low grounds on North river. It is a mass of pulverized shells, 

 colored by red or brown oxide of iron. 



(b) Blue marl.— This is the most common kind in the upper range, or 

 near the western limits of the great marl deposite. Thereabouts, blue marl 

 usually forms the whole thickness of the bed. More eastward, and lower 



