■%Vl AGRICULTURAL REPORT. [1377, 378, 379 



s Cohr, therefore, has nothing to do with characterizing any substance as a clay. 

 I 'hive bsdn fchas particular in stating this point, biciusa of the difficulty I have 

 co often enounte re I in arriving it a definite oon;lu-uonc m-ernin* soon miteri- 

 •ai describe! to me, the party whom [ qujstioned insisting that it was not clay, 

 merely on account of some unusuil tint it happenoi to possess. 



377. " STrpito7ie" — It ts very usual in this Sttte to hear designated as "soap- 

 stone" any clay which, being free from coarse particles, is smooth to the touch, 

 like soap or true snapstone, and which does not readily form a plastic paste with 

 waiter. The bluish laminated clays of the Eutaw Group of the cretaceous 

 formation (.IT 101, If.), as well as similar clays occurring in the Tertiary (Hlbo, 

 23i), are invariably so designated in the counties in which they occur. 



True Soapstonc, such as is used for the interior lining of stoves, for hcarth- 

 plates and ovens, does not occur within t'le State; the formations to which it 

 belongs are entirely wanting, and all the "soapstone" commonly so called in 

 Mississippi, belongs to the class of clays above described When vvoiked up 

 wirli water, they gradually form a very tenacious mas^, wlrch, however, usu- 

 ally contains too little sand to be suited to the purposes of the potter, in ns 

 natural stale. 



. 178. Retentive Powers of Clays — One of the most important properties of clays, 

 w^hx-h they impart, in greater or less degree, to all soils, is their capacity of 

 retaining in their muss a certain amount of the ingredients necessary for the 

 growth of plants, even when these are in a condition in which, ordinarily, they 

 are soluble in water. When soluti >ns of potash, lime, phosphoric acid, etc, are 

 ffiiered through a liver of soil of sufficient thickness, the whole of these ingre- 

 dients is retained by the soil, so that the waterwhich drains from it con- 

 • tains no more of them. This rete .tive power, which varies very much in 

 rent soils, is ol the ve'y highest importance, as it prevents the waste of 

 "Ji ! itiaole ingredients by the action of the ruin water which continually filters 

 "in \ drains ihroiCgh the soil Hence it is that in the waters which drain from 

 pre-eminently rich in soluble ingredients, traces only of these sukstan- 

 3CS can be discovered, unless indeed, the soil should happen to he Siturcrted 

 with some of them, so as to be unable to retain an additional supply ; as a 

 Sponge will not receive, or retain, more than a certain amount of water. 



The point of saturation differs for different substances ind one an the same soil ; 

 a?rd it is remarkable that in legard to the retentive power, there is a marked 

 distinction in favor of those sulistances most generally needed by the plants in 

 large quantities. Thus potash and phosphoric acid are most pertinaciously 

 retained, while soda, magnesia and soluble vegetable acids are often carried off 

 in large proportions by the drain waters. Light and sandy soils are the least 

 retentive of these substances, as well as of moisture ; while clayey soils, and 

 those containing much vegetable matter, are the most retentive of both. 



Clays are retentive, not only of solids and liquids, however, but also of gases, 

 "srad particularly so of ammonia ; hence they condense the latter from the atmos- 

 phere, thus furnishing it to the roots of plants. In this, as in other lespects, 

 c'.ays act analogously to humus, concerning which, see below under the head of 

 manures (IT 425V 



'379. u Ah<m." — Next to the combination of Alumina with silica, which is 

 the 'oasis of clays, its combination with sulphuric acid deserves mention. This 

 -dries not often occur in substance, but is not an unfrequent ingredient of the 

 x<vneral springs issuing from the lunitic clays ; which are commonly distin- 

 guished as "Alum springs" The nam", though not strictly coirect (inasmuch 

 as i j lie alum contains sulphate of p>t"s'i nesde thatol alumina), well expresses 

 hi r-sweetsh astringent taste possessed by such waters, hi this State, they 

 ilways issue from the lignitie strati o'' the tertiary fo rrntion, and are mist 

 lint in those which are immeda ely contiguous to the tnarin ", fossil iferous 

 Tertiary. The strongest alum water in the Stite of wh : ch I have any personal 

 knowledge, is that of liaugh's well, at Brandon, Rankin county ; otu \cry 



