mouths of rivers; namely a compound of the common | to meet with the old proverb, or have taken a journey sand and mud: the other appears, to the eye, clean into the sandy district of Norfolk. We really do not fragments of broken shells, without mixture; resemb- know whether it be as old Jervais Markham, or not; ling, in color and particles, clean-dressed bran of wheat. but we have seen the following lines in black letter: "By analysis, one hundred grains of the former contain about thirty grains of common silicious sea sand, He that marls sand, may buy land; with a few grains of fine silt or mud; the rest is calcaHe that marls moss, shall have loss; reous earth, mixed with the animal matter of marine He that marls clay, throws all away!" shells. his admitted ignorance serves to prove that the The editor then passes to a subject on which improvement gained by marling could not be simply the making a soil calcareous-for upon that ground, when marl has once been plentifully given, and the land afterwards worked poor, there can be neither reason nor profit, in a second marling. Yet, as if the mode of operation was altogether unknown, this passage follows.

"One hundred grains of the latter contain eightyfive grains of the matter of shells, and fifteen grains of an earthy substance, which resembles, in color and particles, minute fragments of burnt clay, or common

red brick.

"These sands are raised in different parts of Plymouth Sound, or in the harbor; and are carried up the estuaries, in barges; and from these, on horseback, perhaps five or six miles, into the country; of course at a very great expense: yet without discrimination, by men in general, as to their specific qualities. The shelly kind, no doubt, brought them into repute, and induced landlords to bind their tenants to the use of them; but without specifying the sort-and the bargemen, of course, bring such as they can raise, and convey, at the least labor and expense. It is probable that the specimen first mentioned, is above par, as to quality: I have seen sand of a much cleaner appearance, travelling towards the fields of this quarter of the country: and, near Beddiford; in North Devonshire, I collected a specimen, under the operation of "melling" with mould, which contains eighty grains per cent. of clean silicious sand!" -Marshall's West of England, Vol. I. page 154.

"It was once asked of the editor by a very good practical Norfolk farmer, 'whether land which had been once marled and worn out, would receive the same benefit from a second marling?' It was answered, that an experiment made on one field, or on one acre, would decide the point, but conjecture led to nothing conclusive. It has often been observed that loose land, after having been marled and out cropped, deposited its marl in the subsoil, which therefore became more retentive [of water; ] and it has been suggested, that deep ploughing ought to be tried, to bring this marl again to the top. We hope that the point here in question, has before now been settled by practice in both ways; though at the above period, (about 1806) such facts had not reached the gentleman alluded to, although a very intelligent man.'

It might be inferred from all these proofs of Marshall's knowledge of calcareous earth constituting the real value of marls, that he could scarcely miss the evident corrollary to that proposition, The singular fact stated above, of marl, and also that the valuable operation of calcareous manures of lime, sinking and forming a layer below the is to render soils more calcareous-and that the soil, is stated by other British writers. No such knowledge of the nature of the manure and the result has been found in this country, so far as I soil, would sufficiently indicate when the applica- am informed. Nor do I believe that it can occur, tion of the one to the other was judicious or not. except when the calcareous matter is too abunBut the following expression of opinion (Mar-dant to form a chemical combination with the soil, shall's Yorkshire, Vol. I. p. 377) is not only strongly opposed to those deductions, but to the general purport of all his truths which I have before quoted.

23. "Nothing at present but comparative experiments can determine the value of a given lime, to a given soil; and no man can, with common prudence, lime any land, upon a large scale, until a moral certainty of improvement has been established by experience."

or with the matters in the soil. According to my views of the manner in which calcareous earth acts, it must form such combinations in the soil, to be useful-and if so combined, it cannot be separated, and sink through the soil by the force of gravity, or any other cause.

30. The next article is probably one of the latest publications on marl, yet contains as little of truth, and for its length, as much that is false and absurd, as if it had been written a century ago. It If this be true, then indeed is there no true or appears in the last number of the Quarterly Jourknown theory, or established precepts, for apply-nal of Agriculture, (for Dec. 1834) and is there ing either lime, or any calcareous manure. It amounts to saying, that every new application is a mere experiment, the result of which cannot even be conjectured from any facts previously known of other soils and other manures.

quoted from the Magazine of Gardening and Botany, and as written by Count Gyllenborg. As no contradictory remarks are appended by either of the editors of these highly respectable journals, it may be considered as in some measure giving 29. The next quotation, which is from an edi- countenance to the opinions here presented." torial article in the Farmer's Journal of July 28, Though the writer speaks of "acid in the land,” 1823, shows that the old opinion still prevails, that yet the succeeding part of the sentence which marl is profitable only on sandy lands; which opin-speaks of "imbibing it from stagnating water" ion carries with it the inference that it is the ar- shows that no correct or definite idea was attached gillaceous quality, rather than the calcareous, that to the term "acid." The entire piece is copied. operates. The editor is remarking on a new agricultural compilation by a Mr. Elkinson, and ridiculing the author for his solemn annunciation of the truism (in the editor's opinion,) that, "marlin on sand is more useful than on clay land." The reputation of Mr. Elkinson, says the editors,

may remain undisturbed among the farmers of LinInshire for a long time, who may never have chanced

"How far marl contributes to the fertility of soils. 1st, Not materially, for it is devoid of every unctuous and saline matter. 2d, But instrumentally, it promotes vegetation, by attracting the moisture, acids or oils in the atmosphere, which enrich the land. As this quality becomes stronger by burning, how wisely would the farmers act in using it after being calcined. It promotes vegetation, by destroying the acid actually in the land, or removing that which it might be in danger of

imbibing from stagnating water, and hence, also, it may perhaps help to prevent a too acid disposition in the seeds. By dissolving every unctuous substance in the land, whence arises a saponaceous mixture soluble in water, and fitted to enter into the pores of vegetables. By destroying the toughness of strong soils, for, by its quickly crumbling in the air, the cohesion of a clayey soil is diminished, it is rendered easier to cultivate, and more fit to carry on growth of plants. It gives greater solidity and firmness to loose or sandy soils; and, as before observed, it contributes to their fertility, by attracting into this dry soil the nutritive contents of the air. There are some who think that marl should not be laid on sandy soils; but experience has taught us to conclude otherwise, having observed that the most beneficial effects are produced from it on very light and sandy soils. Marl may hurt land by too long and a too plentiful use of it; for, from its calcareous quality, it much resembles lime. It soon dissolves and consumes the fat of the land-and it loosens a clayey soil, so that it becomes less retentive of moisture. Marl is, however, very different, according to its being more or less calcareous or clayey; and therefore, judgement is more or less necessary to adapt it to the nature of the soil. Some have recommended it chiefly for wet and cold soils, and many farmers have observed that it is most useful when mixed with rich manures. Neither of these observations, however, seems to be correct; but a due care should be taken that this manure be adapted to the soil on

which it is laid."

[NOTE G 2. Page 36.]

A close examination showed some fragments of the hardest shells, so as to prove that the old man had not mistaken the spot. This, like other early applications, had been made on a spot too poor for marl to show but very small early effects-and as only one kind of operation of any manure was then thought of, (that which dung produces,) it is not strange that both the master and servant should have agreed in the opinion that the application was useless, and have remained under that opinion until almost all remembrance of the experiment had been lost.

There were also successful and continued uses of this manure in James City County, in Virginia, made earlier than mine; and still earlier by the Rev. John Singleton, in Talbot County, Maryland. It appears that the early (though chance directed) combination of putrescent manures with marl in both these places, served to prove the value of the latter, and perhaps to prevent it being there also abandoned as worthless, as in other cases. But though the application was continued, and with great success and profit, the knowledge of these facts, and the example, extended very slowly: and the then want of communication among farmers, for years kept all ignorant of these practices, except in the immediate vicinity of the commencement of each. I have since erdeavored to ascertain the time of the first applications in James City, and have been informed that it was in 1816. Mr. Singleton's, in Maryland, were begun as early as 1805. His own account

THE EARLIEST KNOWN SUCCESSFUL APPLI- of his practice (which will be annexed entire, as

CATIONS OF FOSSIL SHELLS AS MANURE.

an interesting statement of the earliest profitable use of this manure,) was first published in 1818, in the 4th volume of the Memoirs of the Philadelphia Agricultural Society, (page 238.) The date of his letter is Dec. 31, 1817. My first experiment was made the following month (Jan. 1818,) but more than a year before I met with Mr. Singleton's publication, or had heard of any application of fossil shells, except the two failures mentioned in page 36. But however beneficial may have been found the operation of marl in Talbot and in James City, it is evident, from Mr. Singleton's letter, and from all other sources of information, that the mode of operation remained altogether unsuspected by those who used it: and this was perhaps the principal cause why the practice was so slow in spreading. It is now thirty years since the first proofs were exhibited on the land of Mr. Singleton: yet, according to the report of the geological survey of the lower part of Maryland, (submitted to the legislature of Maryland at its recent session of 1834-5,) it appears, that though the value of marl is well understood, and much use of it made in Talbot county, and part of Queen Anne's, it also appears that almost no use has been made of it on the other and much more extensive parts of the Eastern Shore of Maryland-and none whatever west of the Chesapeake in that state, where it is found in abundance. Such at least are the inferences from Mr. Ducatel's report, though in part drawn from direct testimony, more than direct and particular as

The two old experiments described at page 36, though the only applications of fossil shells known to me, previous to the commencement of my use of this manure, were not all which had been made, and which being deemed failures, had been abandoned and forgotten. Another, within a few miles of my residence, was brought to light and notice afterwards, by an old negro, who was perhaps the only person then living, who had any knowledge of the facts. After I had found enough success in using this manure to attract to it some attention, Mr. Thomas Cocke of Aberdeen was one of those who began, but still with doubt and hesitation, to use marl to some considerable extent. One of his early applications was to the garden. The old gardener opposed this, and told his master that he knew "the stuff was good for nothing, because when he was a boy, his old master (Mr. Cocke's father) had used some at Bonaccord, and it had never done the least good." Being asked whether he could show the spot where this trial had been made, he answered that he could easily, as he drove the cart which carried out the marl. The place was immediately sought. It was on the most elevated part of a very poor field, which had been cleared and exhausted fully a century before. The marled space (a square of about half an acre) though still poor, was at least twice as productive as the surrounding land, though a slight manuring from the farm-yard had been applied a few years before to the surround-sertions. ing land, and omitted on this spot, which was supposed to have been, from its appearance, the site of some former dwelling house, of which every evidence had disappeared except the permanent improvement of the soil usual from that course.

The slight, and almost contemptuous manner, a which marl is mentioned by so well informed an agriculturist as Taylor, as late as 1814, when his Arator was published, (and which remains unaltered in his 3d edition of 1817,) proves that al

most nothing was then known of the value of this I have here; as, besides the scallop shells, which are manure. All that seems to relate to our fossil shells not so much reduced as here, there is, for perches is contained in the two following passages: together, the clam shell, perfectly whole, but so soft, "Without new accessions of vegetable matter, suc-air, they soon fall away to powder: but the scallop that when thrown out of the ditch and exposed to the cessive heavy dressings with lime, gypsum, and even shell seems most abundant; and of this kind of shellmarl, have been frequently found to terminate in im- fish we have no knowledge. The beds of shell are to poverishment. Hence it is inferred, that minerals ope- be discovered in many places, on the edges of the rate as an excitement only to the manure furnished by creek, and even out into the water; and are found the atmosphere. From this fact results the impossibility throughout the county, in most places where carefully of renovating an exhausted soil, by resorting to fossils, which will expel the poor remnant of life; and indeed sought for, but generally, I believe, a good deal mixed it is hardly probable that divine wisdom has lodged in the be usefully applied as improvers of the soil: they are with sand. However, I have no doubt they may all bowels of the earth, the manure necessary for its surface."-Arator p. 52, 2nd Ed. Baltimore. now coming into the use of many persons in this have adopted a regular system of manuring. county, who have discovered them on their land, and

"Of lime and marl we have an abundance, but experience does not entitle me to say any thing of either."-p. 80.

From the Rev. John Singleton, to the Hon. Wm. Tilghman.

*

"Your first question is, 'whether what I use be marl, or soil mixed with shells?'

"Your next question is, to what kind of soils, and how it is applied; as a top dressing or ploughed in?" of which is a cold white clay, and wet; others a light "I have applied it to all the soils on my farm, some loam, and sandy, I find it useful to each kind, and manure my land all over with it, without distinction, and to advantage; putting a smaller quantity upon the "Whether it be marl or not, I will not pretend to deter- looser soils. I have applied it as a top dressing on clomine, as I have seen no description of marl that answers ver, and also where clover has not been sown, with a exactly to it; but Mr. Tench Tilghman informed me, view to improving the grass, and also to be satisfied he had seen a description of marl used in Scotland, ex- whether it would not be best for the ground, to let it lie actly similar to what I use on the farm on which I re- spread on the surface, for a year before the ground was side, and which is the improved land you mention. I put into cultivation. But it has not answered my expechave not seen the account myself. However, this, and tation. I could not perceive any advantage from that all mixtures of broken marine shells, of which there is a mode of application. I now constantly apply it to great variety, are now denominated marl, here. What the ground cultivated in corn; carting it out in the winI consider the best, and which I most use, is composed ter and spring, and putting on from twenty to forty of small parts of marine shells, chiefly scallop shell, cart loads per acre, according to the ground, and the about one-eighth of an inch square, or somewhat previous quantity that had been put on, in former cullonger or smaller, with scarce any sand or soil with it: tivations, dividing each load into from four to eight some of it seems to be petrified, and is dug up in lumps, small heaps, for the greater ease in spreading, accordlike stone, from four or five, to forty or fifty pounds in ing to the size of the load. Some is put on before, and weight, hard to break even with the edge of an axe, some after the ground is broken up, but it is all worked and will remain for years, tumbled about with the into the soil by the cultivation of the corn, and it never plough, before it is entirely broken to pieces, and mix- fails of considerably improving the crop of corn, as ed with the indeed you may observe it in some also the ground wherever the marl is, especially in parts of the bank, where the soil has been washed from largest quantity. There is a small green moss, and it, appearing like rock stone; but if broken and pulver-black moist appearance, on the surface of the ground, ized a little, it effervesces very much with acids. It lies from three to five and six feet deep, from the surface of a light or sandy soil, on the banks of the cove; but how deep the marl, or bed of shells goes, we cannot ascertain, having never dug through it. When we get from two to four feet deep into it, the water springs, so that we have never gone deeper, but fill up the hole with the surface soil, and open another. It does not lie level, but waving, sometimes dipping so deep that we lose it; nor is it of one color, but some white, like dry mortar, some the color of yellow ochre, some red, like red ochre, and some blueish: but I do not know any difference in the quality, from the color. In digging, it is generally loose and crumbly, but mixed with hard lumps as above described: we find sometimes whole shells of scallop, oyster, and barnacles. The kind I estimate most, is of the foregoing description, and I am of opinion it lies at different depths, under the whole of this peninsula, which has been gained from the water, and that the shells are of the different kinds of fish which inhabited the waters while they covered the land. In some places, at heads of coves, I have traced the shells by cutting a ditch from three to five feet deep, down the valley, and even through the marsh, till I came to tide water; but in this kind of low ground there were more whole, and large shells, and nore of the large stone-like lumps above mentioned. It appears as if it had been the bottom of the creek, and as if covered by the water more lately than the fact described. All these are on this farm. At my other farm, where my uncle formerly lived, and which is at the head of this creek, I find it by digging deep into the ditches, in the meadow ground, which empty into the head of the creek: but that kind differs from what

when not cultivated; as you perceive about old walls, and in strong ground. Though the preceding is the common mode in which I use the marl, I do not think it the best; I mix some in my farm yard, with the farm yard and stable manure; and would prefer mixing and applying all that I use thus mixed, but for the labor of double cartage, which I cannot as yet accomplish, manuring so largely as I do. I cultivate one hundred acres yearly, and constantly manure the whole of what I cultivate; employing only four carts, and four hands with the carts, which do all the manuring and carting on the farm.

"Your next question is, 'what has been my rotation of crops, and mode of cultivating, since I have used this manure?"

"Since I began to use the marl, and bend my attention to improvement by manure, I have cultivated only corn and wheat, sowing my ground in clover, and using the plaster. Instead of cultivating all my ground in corn, and sowing wheat on it as heretofore, I divided my cultivation into two parts, of fifty acres each, putting one part into corn, which I was able to accomplish manuring time enough for the corn, and making a fallow of the other part, manuring as much of it as I could accomplish before the time for sowing wheat; and disregarding, in a degree, all smaller crops, which I could not attend to, as an object, without increasing my number of hands, and interfering with the main business. I went on in this manner, till I found I could easily accomplish manuring one hundred acres and upwards, per annum. Having got my ground to that state that I can risk making a crop without manure, I am now about discarding fallow, being able to manure my whole hundred acres time enough for cropping in the

tivation. By this means, and the divine assistance, I have effected that improvement of my farm, which is so very striking to the observation of every person acquainted with it. I can say nothing as to the comparison of crops, before and since my improvement: it has been a progressive thing for many years, and, till I adopted the present plan, I was an experimental farmer, trying every thing I met with in books, or heard of; so that there is scarce any rotation of crops, or mode of cultivation, but what I have tried.

"This I believe, will answer all your questions, except as to the time when I began to use the marl, and how soon I experienced the beneficial effect of it?

spring, by beginning to manure for the next year as soon as the spring manuring is finished. I shall in future have no wheat in fallow, but sow it after corn and other crops, from which I am satisfied I can make more from my ground than by naked fallow, which I always considered unprofitable, though you made more wheat, except for the advantage of having more time to manure. The standing annual force on my farm is eight hands, (men,) with one hired by the month. Of these hands four are employed with the carts; two in ploughing, harrowing, &c. for the cultivation of the crop; and the other two or three, as may be, do the blacksmith's and carpenter's work, as also the fencing and other work necessary on a farm: the six hands employ-being your fourth question. ed with the carts and ploughs, are not taken off for "In August, 1805, in digging down a bank on the other business, except in the time of harvest, and sow-side of a cove, for the purpose of making a causeway, ing wheat, when they are probably stopped. I do not I observed a shelly appearance, which it struck me work much with the plough as formerly, but more might improve clay soil; I took some of it imediately with the harrow, which lessens and quickens the labor to the house, and putting it into a glass with vinegar, of cultivation, keeps the ground cleaner, and, I think, found it effervesced very much; this determined me to in better tilth. Occasionally I hire or employ some try it as a manure; accordingly, in September, I carted women, for hoeing work and spreading manure. I out about eighty cart loads, and put it on a piece of flush my ground in large lands, and harrow and roll as ground, fallow, preparing for wheat, trying it in difit may require; then, instead of listing, as common, ferent proportions, at the rate of from twenty-seven to mark it out each way with a plough, very shoal, so as about a hundred loads per acre, and the ground was not to disturb the grass ploughed down, and after drop- sown in wheat. I could not, myself, be satisfied that ping the corn, cover it with the plough or harrow, and there was any difference through the winter and spring, immediately put in the harrow, keeping it going, as although general Lloyd, who was viewing it with me the weather will permit, till just before harvest, in the spring, thought he could perceive some differwhen we plough the ground, and finish the culti-ence, in favor of the marl; but at harvest time, the vation with the harrow, except something should wheat, though not more luxuriant in growth, or better occur, making it necessary to plough again after head, was considerably thicker on the ground; and after harvest. This I have found the best mode of cultiva- the wheat was taken off, the ground where the marl tion for corn. I plant my corn about four feet apart had been put was set with white clover, no clover beeach way, and have from three to five stalks in a hill, ing on the ground on either side of it. The next year, or cluster, for I endeavor to keep down the hill, and 1806, I discovered it in the drain into the head of the have the ground as level as possible. In saving my cove, which I immediately ditched, and from the ditch corn crop, I cut it up, without pulling it from the stalk put out seven hundred loads, on the fallow ground. The as usual, and cart it in all together, then husk it out, effect, as to the wheat and clover, was the same, (this leaving the husk to the stalk: I lay these near my feed- was put, for experiment, at the rate of from forty to a ing yard, and throw them into it twice a day: this gives hundred and twenty cart-loads per acre,) though the us a large quantity of strong healthy food for the cattle, marl was not of the same kind as the other, but more which serves them all winter, and keeps them in good mixed with sand and surface soil, being taken from the condition without any other food; makes a large quan- low ground, by ditching, and all mixed together. I tity of excellent manure, and a fine dry feeding yard. also tried it on corn ground, spread out as above mcnAs opportunity can be found, we cart marl, fuller's tioned, and found the effect immediate, as to the corn; earth, clay, and any good soil that is convenient, into this and in the same manner as above described, as to the yard, which being mixed with the stalks, and straw, or wheat sown on the corn ground. This induced me to any thing else, penning the cattle on it through the persevere in the use of it, which I have done ever since, winter and summer, instead of penning on the field, adopting the mode I mentioned before, and putting it at in the common way, we have a large quantity of ma- first from forty to seventy loads per acre, till I have now nure to go out in the fall, and next winter; it is put into come down as low as eighteen or twenty loads per acre, the field, in the intermediate rows, between the rows going the third time over the ground with it. of marl, as far as it will go, and they will get mixed in the cultivation. We also convert the scouring of our ditches, the head-lands of the fields, and all wasteground that we can, into manure, by carting litter from the woods, yard manure, or litter, &c. &c. and mixing with them; so that I can nearly, or quite, now, accomplish making farm-yard and this kind of manure, sufficient to go over my whole hundred acres, annually. For the two last years, I have made more manure than I could accomplish or effect carrying out, though I have manured from ten to twenty acres more than my hundred, each year, with part marl and part farm-yard, but not the whole with both, as I hope to be able to do in future; but it will be necessary to increase my carting force to effect it, and I clearly see, I can raise sufficient manure for the purpose; heretofore I have manured my corn-ground, fifty acres, with marl, and my fallow with part farm-yard manure, and part marl, as mentioned before; so that you will perceive the improvement made on my soil has not been effected by marl alone, but in conjunction with farm-yard manure, clover and plaster, and by making it a point to manure with something all the ground I put into cultivation; so that every time I cultivated a field, that field was improved, and not in any degree impoverished by the cul

"I believe I have now answered all your inquiries, as well as I can, except as to the average comparison of the past and present crops, which I cannot well do, for the reasons above given, and also that my fields are entirely changed, neither containing the same grounds, nor the same quantity of ground in each; but I believe I shall not be much out of the way, if I say, that I think the soil now capable of producing between two and three times as much, per acre, as it would before I began to use the marl; and though the marl has not solely produced the improvement, yet the improvement would have been far short of what it is, if it had not been for the marl, which has contributed, in a very large degree, towards it; and no small matter in favor of the marl is, that, by the blessing of God on my endeavors, I have, in twelve years, been enabled to improve three hundred acres of ground, to the pitch that these are, and am now in a fair way of increasing in the same ratio the ta snow-ball increases as it is turned over.

"I fear you will not be able to read, and hardly te understand, this tedious letter, in many parts; 10 ye can, and it is in any degree satisfactory to you, I sh be compensated, and will cheerfully answer ary i quiries, in future, that you may wish to make. 1 first favorable opportunity, which may probably

some friend, in the spring, I propose sending you a small bag of marl, which may be more satisfactory than any description.

JOHN SINGLETON.

Talbot County, Md. Dec. 31, 1817.

[NOTE H. Page 49.]

GYPSEOUS EARTH OF JAMES RIVER, AND THE
GREEN MARL OF NEW JERSEY, BOTH BE-
LONGING TO THE "GREEN SAND FORMA-

TION.

[NOTE I. Page 50.]

THE CAUSE OF THE INEFFICACY OF GYPSUM
AS A MANURE ON ACID SOILS.

soils he may hope for benefit from this manureon what it will certainly be thrown away-and by what means the circumstances adverse to its action may be removed, and its efficacy thereby secured. This is the explanation that I shall attempt.

I do not pretend to explain the mode of operation by which gypsum produces its almost niagic benefits: it would be equally hopeless and ridiculous for one having so little knowledge of the successful practice, to attempt an explanation, in which so many good chemists, and agriculturists both scientific and practical, have completely failed. There is no operation of nature heretofore less understood, or of which the cause, or agent, seems so totally disproportioned to the effect, as the The passage in the text describing generally enormous increase of vegetable growth om a the gypseous earth of Prince George county, is very small quantity of gypsum, in circumstances left as it stood in the first edition, though much favorable to its action. All other known manures, more full developements have since appeared. whatever may be the nature of their action, reThe first piece on the subject, to which the read-quire to be applied in quantities very far exceeder is referred, commences at page 207 Vol. I. of ing any bulk of crop expected from their use. But Farmers' Register. It is a full and minute ac- one bushel of gypsum, spread over an acre of count of the beds in my neighborhood of what I land fit for its action, may add more than twenty have called gypseous earth, and the reasons stated times its own weight to a single crop of clover. at length for believing it to be the same earth However wonderful and inscrutable the fertilknown in New Jersey under the name of marl. izing power of this manure may be, and admitting At that time I had never met with a specimen of its cause as yet to be hidden, and entirely beyond the latter substance, and only inferred its qualities our reach-still it is possible to show reasons why and its chemical constitution (in certain respects) gypsum cannot act on many situations, where all from the loose and general, and very unsatisfac-experience has proved it to be worthless. If this tory statements previously published respecting only can be satisfactorily explained, it will remove that earth. Other subsequent notices in the Far- much of the uncertainty as to the effects to be exmers' Register, at pp. 272, 572,) present addition-pected: and the farmer may thence learn on what al facts or reasons in support of the identity of these formations. Afterwards Professor William B. Rogers discovered what geologists call green sand, intermingled with many of the bodies of marl near Williamsburg, and in an interesting communication to the Farmers' Register, page 129, Vol. II. in which this discovery is announced, he shows what the green sand is, and that it constitutes the valuable portion of what has been erroneously called marl in New Jersey. Mr. R. had not then seen my earlier account of gypseous earth-but reasoning upon geological grounds he inferred that the true green sand formation would probably be found higher up the country, He has since visited and examined the bed of what I had called gypseous earth, at Coggin's Point, Tarbay, and Evergreen, (in Prince George county,) and has found it to be the green sand formation, as was anticipated, and at the same time, confirmed my opinion of the identity of this earth with the New Jersey "marl." The green sand however in Virginia, so far as yet exposed to examination, is not to compare in richness with the best of New Jersey. The very little as yet known of the practical use, or measure of the value of this earth as manure, is in the paper first referred to above. The length of that piece and of Mr. Rogers', and their having been already published in the Farmers' Register, forbid their being again presented in this place: and in addition, it is expected that Mr. Rogers' more recent examinations will enable him to lay before the public a more correct and full acrout, which will of course be more interesting than the early views taken when the existing facts were but partially known-and so far as my own Investigations went, were known to one who had nothing of the geological knowledge necessary to wake proper use of the facts observed.

If the vegetable acid, which I suppose to exist in what I have called acid soils, is not the oxalic, (which is the particular acid in sorrel,) at least every vegetable acid, being composed of different proportions of the same elements, may easily change to any other, and all to the oxalic acid. This, of all bodies known by chemists, has the strongest attraction for lime, and will take it from any other acid which was before combined with it -and for that purpose, the oxalic acid will let go any other earth or metal, which it had before held in combination. Let us then observe what would be the effect of the known chemical action of these substances, on their meeting in soils. If oxalic acid was produced in any soil, its immediate effect would be to unite with its proper proportion of lime, if enough was in the soil in any combination whatever. If the lime was in such small quantity as to leave an excess of oxalic acid, that excess would seize on the other substances in the soil, in the order of their mutual attractive force; and one or more of such substances are always present, as magnesia, or more certainly, iron and alumina. The soil then would not only contain some proportion of the oxalate of lime, but also the oxalate of either one or more of the other substances named. Let us suppose gypsum to be applied to this soil. This substance, (sulphate of lime) is composed of sulphuric acid and lime. It is applied in a finely pulverized state, and in quantities from half a bushel to two bushels the acre-generally not more than one bushel. As soon as the earth is