ANALYSIS OF MARLS. XXXVil 
4. Marly limestone, from Wilmington, N. C. Found in thick beds, contiguous to the Steam Boat Landing. 
This is rather a firm rock, often sub-crystaline and rich in fossils, both zoophytic and molluscous, besides 
containing frequent remains of fish. Certain portions of the bed which are softer and more cretaceous in ap- 
pearance, embrace irregular, oval balls, sometimes of the size of a hazle nut or almond, which are green and 
often mottled like serpentine. Their surface is often sprinkled over with coarse grains of sand. In hydro- 
chlorie acid, they are principally dissolved with rapid effervescence ; from which, ammonia throws down a copi- 
ous precipitate of phosphate of lime and magnesia, and the clear liquor subsequently affords abundance of lime 
and magnesia. The matter not taken up by the acid appears to be sand and green earth. It is not easy to 
explain the origin of these green nodules. The marly limestone has the following composition : 
SilGh, = =). Seen oe ee ete ee hs Sch s oes cannes 16.00 
Garbonate, of lime, and maenesia, 5-39 a nant Sag mie iinins aie 80.00 
Phgaphata.ob imme: ard MA QTC hy ce a ho pe ii OO 
POTN oe oie ann cee ease eee oe oo cae om tec ies 1.00 
Vi CED a Se Se i a eee ee Pa: bee 2 2.00 
101.80 
REMARKS. 
Prior to these analyses, it was difficult to account, in any very satisfactory manner, for the known efficacy of 
such marls in agriculture; since the soils on which several of them had been employed were known by analy- 
sis, to be no more deficient in carbonate of lime and magnesia than the prolific soils of the Mississippi Valley. 
The reason assigned for marling in South Carolina, by Mr. Ruffin, viz: that carbonate of lime is thereby afford- 
ed to land, does not appear to me to be the chief motive the planter has for following up this practice.* It 
would rather appear that the soluble saline matter and bitumen are also among the active ingredients of this 
species of mineral manure, while the phosphate of lime and magnesia, is that constituent which, in my opinion, 
is decidedly paramount to all others. 
This view of the efficacy of phosphatic marls accords with what is known of the large proportion of phos- 
phate of lime and magnesia found in the fruits of plants, and especially in those of the cereals; it having 
been observed that where this amendment is employed, that the maturation of the grain is more perfect, the 
quantity and quality both, being highly promoted. 
To place the requisition of these phosphates by plants, especially in the ripening of seed, in a still stronger 
light, I may, in conelusion, quote the recent experiments of Dr. Vogel, (See Annalen der Chimie und Phar- 
macie, 1844,) on the distribution of mineral substances by the individual organs of plants. This interesting 
paper commences with the statement of what was known before, viz: that the incombustible residues obtained 
from different organs of the same plant do not agree with one another in composition; the ingredients being 
often quite different in kind, and always in their proportions. For instance, the ashes of the tubers of the po- 
* This writer, in his Reporton the Agricultural survey of this State, (p. 51, et seq. 1843,) observes, that this ingredient has a strong 
chemical attraction for soluble, putrescent matters, vegetable and animal, and a power of combining with them, forming compounds 
which cannot be decomposed by air, water or heat, and which cannot therefore go to waste, but which are perfectly decomposable 
by the powers of growing vegetation, and therefore may. be profitably and entirely used as food for plants. Herein, he observes, is 
the great secret of the benefit of Calcareous manures. Other useful services enumerated by the same judicious writer, are their 
neutralizing the acidity of certain soils, altering the texture and absorbency of others, causing crops to mature earlier; also as being 
an essential aliment of plants, of preventing malaria, and finally of serving to impart to plants such a heal:by and vigorous state of 
growth as to enable them / escape the ordinary sources of injury. ; 
K 
