MARL. 



561 



lime to the soil iu our day. Even the masses of 

 much smaller, cong-lomerated shells, though very 

 rich in lime, are not among the most valuable 

 marls, unless broken up and pulverized to a con- 

 siderable extent. There is a marl abounding vv'ilh 

 us, which to the naked eye seems to be mere 

 sand, that is much more valuable, though it does 

 notcontain two-thirds of the quantity of carbonate 

 of lime : mixes at once with the soil and exerts 

 its full influence in a comparatively short period. 

 The most valuable marl, practically speaking, 

 that is found in any quantity at Shell Bluff — and 

 will be found in your marl-beds, for the fonna- 

 tion is the same- — is composed of very tine shells, 

 scarcely discernible, which are loosely cement- 

 ed together and readily fall apart. It is of dif- 

 ferent colors ; mostly white, sometimes purpli.sh. 

 yellow, or light brown. The most abundant 

 marl found in our formation is hard and com- 

 pact, of a gray color, containing 50 to 60 per 

 cent, of lime, and crumbles on exposure to the 

 seasons anl in handling. 



But. as I have said, the value of marl cannot 

 be estimated by its appearance. Between 

 earth which contains 75 per cent, of carbonate 

 of lime, and that containing 20 per cent, or even 

 none at all. tlie most experienced are far oftener 

 than otherwise unable to distinguish without 

 using the proper tests. These are so readily lo 

 be procured, and in fact the analy.sis of marl, so 

 far as to a-sceitain the quantity of carbonate of 

 lime, is so very simple an opera^n, that the 

 marler should leave nothing to conjecture on 

 this important point. Earth containing any 

 notable proportion of carbonate of lime, will ef- 

 fervesce if thrown into vinegar or almost any 

 acid. But the best test is muriatic acid : a sin- 

 gle drop of it will produce immediate efferves- 

 cence whenever there is carbonate of lime in 

 any marl, it is only necessaiy to have this acid, 

 a pair of apothecaries' scales with weights, and 

 a wide-mouthed vial. Dry the marl thoroughly 

 on a shovel, over the fire, and pound it in a mor- 

 tar to a fine powder. Fill the vial about one- 

 third with the muriatic acid diluted with two 

 parts of water to one of acid, and balance it ex- 

 actly in tVie scales, ^vith weights of any kind. 

 Then add, very slowly, 100 grains of the pow- 

 der previously weighed, taking care not to 

 make it effervesce so rapidly as to throw any of 

 it out of the vial. When the effervescence has 

 completely ceased, blow gently into the mouth 

 of the vial, witli a common bellows, to e.xpel 

 any of the carbonic acid gas which may have 

 remained in it in con.sequence of its being 

 heavier than the atmospheric air. Weights to 

 the amount of 100 grains mast now be put in 

 the opposite scale to balance the 100 grains of 

 powdered marl put into the vial. It will be 

 found that in consequence of the escape of car- 

 bonic acid in a gaseous form, the scale with the 

 vial will rise : put weights into it then until the 

 scales are once more exactly balanced — the 

 number of grains put in the scale with the vial 

 will of course indicate the weight of the car- 

 bonic acid that has es<:apod. Now carbonate of 

 lime contains iu 100 parts very nearly 56 parts 

 of lime and 44 of curb. acid. If, then, 44 grains 

 have escaped in your analysis, the specimen is 

 pure carbonate of lime. If only •22 grains have 

 escaped, then it contains but 50 percent, of car- 

 bonate of lime. And so in proportion to any 

 quantity of carbonic acid which may have been 

 expelled. In practice, it will be found most 

 convenient to u.se .50 grains of the powdered 

 marl. A very few trials will enable the most 

 (1149! 36 



inexperienced farmer to a.scertain in half an hour 

 with sufficient precision the value of his marl. 

 That value depending mainly, as stated, on the 

 quantity of carbonate lime which it contains. 



The value of lime for agincultural purposes, 

 is not only established by the experience of all 

 ages, and, so far a,s we know, of all countries, 

 but must be obvious, when it is known that 

 chemical analysis has detected it tia a constitu- 

 ent of eveiy vegetable that grows on the sur- 

 face of the earth. It is also the chief element of 

 the bones of every animal — even of those that 

 feed on grass only. It is, therefore, not only 

 beneficial, but indispensable to the growth of all 

 kind of vegetation. The all-bouutiful Creator 

 has diffused it over the whole globe, as exten- 

 sively as almost any known substance. But 

 like all His gifts, it has been, for wise and 

 a:ood purposes, no doubt, unequally distributed. 

 That it is placed, in some form and to some 

 extent, within the reach of all plants, is cer 

 tain, since they all contai i it. And a late sci- 

 entific writer on Agricultural Chemistry iu our 

 country, has attempted to prove that all — even 

 the poorest soils, possess an ample supply of 

 it to furnish heavy crops of vegetation for 

 countless years to come. If this were true, 

 it would be worse than useless to expend labor 

 in spreading it over our lands ; millions of farm- 

 ers besides my.self have acted very foolishly, 

 and you would do well to think no more of 

 marling. But this is plainly not the case. There 

 are a great many soils iu which the chemical 

 tests now known, have failed to find a trace of 

 it. Such is the fact with regard, I believe, to 

 all the land I cultivate. Such, I will venture to 

 say, it is with regard to most, if not all of the 

 lands in jour County ; though I am aware you 

 have had pretended analj-ses made, which ex- 

 hibited large proportions of lime. The reason- 

 ing of the writer alluded to, is this : All soils are 

 formed by the disintegration and crumbling of 

 rocks. Most rocks contain lime, especiallv 

 those which disintegrate most readily and form 

 soils. He calculates the amount of lime in the 

 quantum of rock necessary to create a soil of a 

 certain depth, and thence infers that there is so 

 much lime in the land. There is no doubt that 

 the rocks from which your soil and mine were 

 formed, contained lime to the amount estimated, 

 but it is equally certain that these rocks, in their 

 transition from one state to another, were sub- 

 jected for an indefinite period to the action of 

 water. I am speaking particularly of our i in- 

 mediate section of country. The ocean once 

 undoubtedly covered it as high up as the Fal^s 

 of our rivers and the belt of sand-hills which 

 runi through the middle districts of South Caro- 

 lina and Georgia, and held it as pei-manent do- 

 main. During this period, our marl beds were 

 deposited — posi^ibly also our present surface of 

 earth. But whether that be so or not, and 

 v/hether the surface we now cultivate belong-i 

 to the Eocene formation, as these marl deposits 

 are supposed to do, or to the Po.st Pliocene, or, 

 as is most probable, to the Diluvial, it is evident, 

 from the irregular inter-stmtification of different 

 kinds of earth, and the rounded pebbles on and 

 in it, to a considerable depth, which could have 

 been rounded only by the action of water, that 

 the whole of it, like the sand and clay novr con- 

 stantly brought down our streams, lias been at 

 some remote perio<1, " drifted " from a higher 

 region, and deposited by water here. The lime 

 in the rocks being soluble under circumstances 

 which must have attended the " drift.' was re- 



