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grain sowed on the coat of pine leaves, and ploughed in by two-horse ploughs, in as slovenly a manner as may be supposed from the condition of the land-and a wooden-tooth harrow then passed over, to pull down the heaps of leaves, and roughest furrows.

Results. The wheat was thin, but otherwise looked well while young. The surface was again soon covered by the leaves dropping from the now dying trees. On April 2d 1828, most of the trees were nearly dead, though but few of them entirely. The wheat was then taller than any in my crop-and when ripe, was a surprising growth for such land, and such tillage.

1829 and 1830. At rest. Late in the spring of 1830 an accidental fire passed over the land-but the then growing vegetation prevented all of the older cover being burnt, though some was destroyed every where.

1831. In corn. The growth excited the admiration of all who saw it, and no one estimated the product so low as it actually proved to be. A square of four (two pole) chains, or four-tenths of an acre, measured on November 25th, yielded at the rate of thirty-one and three-eighths bushels of grain to the acre.

Experiment 16.

CHAPTER XIV.

EFFECTS OF CALCAREOUS MANURES ALONE,
OR WITH GYPSUM, ON NEUTRAL SOILS.
PROPOSITION 5. Continued.

Applications of calcareous earth alone, to calcareous soils, are so manifestly useless, that only two experiments of that kind have been made, neither of which has had any improving effect that could be observed, in the twelve years that have since elapsed.

When calcareous manures have been applied to neutral soils, whether new or worn, no perceptible benefit has been obtained on the earliest crops. The subsequent improvement has gradually increased as would be expected from the power of fixing manures, attributed to calcareous earth. But however satisfactory these general results are to myself, they are not such as could be reported in detail, with any advantage to other persons. It is sufficiently difficult to make fair and accurate experiments, where early and remarkable results are expected. But no cultivator of a farm can bestow enough care and patient observation, to obtain true results from experiments that scarcely will show their first feeble effects in several years after the commencement. On a mere experimental farm, such things may be possible-but not where the main object of the farmer is profit from his general and varied operations. The effects of changes of season, of crops, of the mode of tillage

the auxiliary effects of other manures-and many other circumstances, would serve to defeat any observations of the progress of a slow improvement, though the ultimate result of the general practice might be abundantly evident.

Another cause of being unable to state with any precision the practical benefit of marling neutral

the calcareous manure thus applied, has been accompanied by a natural admixture of gypsum: and though I feel confident in ascribing some effects to one, and some to the other of these two kinds of manure, yet this division of operation must rest merely on opinion, and cannot be received as certain, by any other than him who makes and carefully observes the experiments. Some of these applications will be described, that other persons may draw their own conclusions from them.

In a field of acid sandy loam, long under the usual cultivation, a piece of five or six acres was covered by a second growth of pines thirty-nine years old, as supposed from that number of rings being counted on some of the stumps. The largest trees were eighteen or twenty inches through. This ground was altogether on the side of a slope, steep enough to lose soil by washing, and more than one old shallow gulley remained to confirm the belief of the injury that had been formerly sustained from that cause. These circum-soils, arises from the circumstance that nearly all stances, added to all the surrounding land having been continued under cultivation, made it evident that this piece had been turned out of cultivation because greatly injured by tillage. It was again cut down in the winter of 1824-5-many of the trees furnished fence rails, and fuel-and the remaining bodies were heaped and burnt some months after, as well as the large brush. In August it was marled, supposed at six hundred bushels (3)-twice coultered in August and September, and sowed in wheat-the seed covered by trowel ploughs. The leaves and much of the smaller brush left on the ground, made the ploughing troublesome and imperfect. The crop (1826) was remarkably good-and still better were the crops of corn and wheat in the ensuing rotation, after two years of rest. On the last crop of wheat (1830) clover was sowed-and mowed for hay in 1831. The growth stood about eighteen inches high, and never have I seen so heavy a crop on sandy and acid soil, even from the heaviest dunging, the utmost care, and the most favorable season. The clover grew well in the bottoms of the old gullies, which are still plainly to be seen, and which no means had been used to improve, except such as all the land had received. Within two feet of the surface the subsoil of this land is of clay, which probably helped its growth of clover.

The cause of these manures being applied in conjunction was this. A singular bed of marl lying under Coggin's Point, and the only one within a convenient distance to most of the neutral soil, contains a very small proportion (perhaps about one per cent.) of gypsum, scattered irregularly through the mass, seldom visible, though sometimes to be met with in small crystals. The calcareous ingredient is generally about 53 -sometimes fo If this manure had been used before its gypseous quality was discovered, all its effects would have been ascribed to calcareous earth alone, and the most erroneous opinions might thence have been formed of its mode of operation.

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What led me to suspect the presence of gypsum in this bed of fossil shells, was the circumstance that throughout its whole extent of near a mile along the river bank, this bed lies on another earth, of peculiar character and appearance, and which, in many places, exhibits gypsum in crystals of

The whole field afterwards was put in wheat on summer fallow every second year, and grazed the intervening year-a course very unfavorable for observing, or permitting to take place, any ef fects of gypsum. Nothing more was noted of this experiment until 1825, when cattle were not turned in until the clover reached its full size. The strip covered with gypseous marl showed a remarkable superiority over the other marled piece, as well as the land which was still more calcareous by nature, and which had produced better in 1820. In several places, the white clover stood thickly a foot in height.

Experiment 18.

A strip of a quarter acre passing through rich black neutral loam, covered with gypseous marl at two hundred and fifty bushels.

various sizes. This earth has evidently once been a bed of fossil shells, like what still remains above --but nothing now is left of the shells, except numerous impressions of their forms. Not the smallest proportion of calcareous earth can be found-and the gypsum into which it must have been changed (by meeting with sulphuric acid, or sulphuret of iron,) has also disappeared in most places; and in others, remains only in small quantities-say from the smallest perceptible proportion, to fifteen or twenty per cent. of the mixed mass. In some rare cases, this gypseous earth is sufficiently abundant to be used profitably as manure, as has been done, by Mr. Thomas Cocke of Tarbay, as well as myself. It is found in the greatest quantity, and also the richest in gypsum, at Evergreen, two miles below City Point. There the gypsum frequently forms large crystals of varied and beautiful forms. The distance that this bed of gypseous earth extends is about seven miles, interrupted only by some bodies of lower land, apparently of a more recent formation by alluvion. In the of bed gypseous marl above described, there are regular layers of a calcareous rock, which was too hard to use profitably for manure, and which caused the greatest impediment to obtaining the softer part. This rock contains between eighty- the marled strip could again be easily traced, by five and ninety per cent. of pure calcareous earth, the entire absence of sorrel, (which had been besides a little gypsum and iron. It makes excel- gradually increasing on this land since it had been lent lime for cement, mixed with twice its bulk of secured from grazing,) and still more by its very san-and has been used for part of the brick- luxuriant growth of bird-foot clover, which was work, and all the plastering of my present dwell-thrice as good as that on the adjoining ground. ing house, and for several of my neighbors' houses. The whole body of marl also contains a minute proportion of some soluble salts, which possibly may have some influence on the operation of the substance, as manure, or cement.

Thus, from the examination of a single body of marl, there have been obtained not only a rich calcareous manure, but also gypsum, and a valuable cement. Similar formations may perhaps be abundant elsewhere, and their value unsuspected, and likely to remain useless. This particular body of marl has no outward appearance of possessing even its calcareous character. It would be consider ed, on slight observation, as a mass of gritty clay, of no worth whatever. [Appendix H.]

This gypseous marl has been used on fifty-six acres, most of which was neutral soil-and generally, if not universally, with early as well as permanent benefits. The following experiments show results more striking than have been usually obtained, but all agree in their general character.

Experiment 17.

1819. Across the shelly island numbered 3, in the examinations of soils, (page 19,) but where the land was less calcareous, a strip of three quarters of an acre was covered with muscle-shell marl. Touching this through its whole length, another strip was covered with gypseous marl, () at the rate of two hundred and fifty bushels.

Results. 1819. In corn. No perceptible effect from the muscle shells. The gypseous marling considerably better than on either side of it.

1820. Wheat-less difference. 1821. Grazed. Natural growth of white clover thickly set on the gypseous marling, much thinner on the muscle-shells, and still less of it where no marl had been applied.

Results. 1818. In corn. By July, the marled part seemed the best by fifty per cent., but afterwards the other land gained on it, and little or no difference was apparent, when the crop was matured.

1819. Wheat-no difference.

1820 and 1821. At rest. In the last summer

Experiment 19.

1822. On a body of neutral soil which had been reduced quite low, but was well manured in 1819 when last cultivated, gypseous marl was spread on nine acres, at the rate of three hundred bushels. This terminated on one side at a strip of muscleshell mar ten yards wide-its rate not remembered, but it was certainly thicker in proportion to the calcareous earth contained, than the other, which I always avoided laying on heavily, for fear of causing injury by too much gypsum. The line of division between the two marls, was through a clay loam. The subsoil was a retentive clay, which caused the rain water to keep the land very wet through the winter, and early part of spring.

Results. 1822. In corn, followed by wheat in 1823: not particularly noticed-but the benefits must have been very inconsiderable. All the muscle-shell marling, and four acres of the gypseous, served in red clover, which stood well, but was severely checked, and much of it killed, by a drought in June, when the sheltering wheat was reaped. During the next winter (by neglect) my horses had frequent access to this piece, and by their trampling in its wet state, must have injured both land and clover. From these disasters the clover recovered surprisingly; and in 1824, two mowings were obtained, which though not heavy, were better than from any of my previous attempts to raise this grass. In 1825, the growth was still better, and yielded more to the scythe. This was the first time that I had seen clover worth mowing on the third year after sowing-and had never heard of its being comparable to the second year's growth any where in the lower country. The growth on the muscle-shell marling was very inferior to the

other, and was not mowed at all the last year, being thin and low, and almost eaten out by wire grass.

1826. In corn-and it was remarkable that the difference shown the last year was reversed, the muscle-shell marling now having much the best

crop.

In these and other applications to neutral soils, I ascribe the earliest effects entirely to gypsum, as well as the peculiar benefit shown to clover, throughout. The later effects on grain, are due to the calcareous earth in the manure,

Another opinion was formed from the effects of gypseous marl, which may lead to profits much more important than any to be derived from the limited use of this, or any similar mineral compound-viz: that gypsum may be profitably used after calcareous manures, on soils on which it was totally inefficient before. I do not present this as an established fact, of universal application-for the results of some of my own experiments are directly in opposition, But however it may be opposed by some facts, the greater weight of evidence furnished by my experiments and observations, decidedly supports this opinion. If correct, its importance to our low country is inferior only to the value of calcareous manures-which value, may be almost doubled, if the land is thereby fitted to receive the wonderful benefits of gypsum and clover.

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gave four bushels of pure gypsum,) on clover, and produced in some parts, a growth I have never seen surpassed. It is proper to state that such results have been produced only by heavy dressings. Mr. Thomas Cocke of Tarbay has this last spring (1831) sowed nearly four tons of Nova Scotia gypsum on clover on marled land, a continuation of the same ridge that my 1st, 2d, 3d, and 4th experiments were made on, and very similar soil. His dressing, at a bushel to the acre, before the summer had passed, produced evident benefit, where it is absolutely certain that none could have been obtained before marling,

On soils naturally calcareous, I have in some experiments greatly promoted the growth of corn, by gypsum, and have doubled the growth of clover on my best land of that kind. When the marl containing gypsum was applied, benefit from that ingredient was alınost certain to be obtained,

All these facts, if presented alone, would seem to prove clearly the correctness of the opinion, that the acidity of our soils caused the inefficacy of gypsum, and that the application of calcareous earth, which will remove the former, will also serve to bring the latter into useful operation. But this most desirable conclusion is opposed by the results of other experiments, which though fewer in number, are as strong as any of the facts that favor that conclusion. If the subject was properly investigated, those facts, apparently in opposition, might be explained so as no longer to contradict this opinion-perhaps even help to confirm it. Good reasons, deduced from established

the acidity of our soils should prevent the operation of gypsum: but it may be deemed premature to attempt the explanation of any supposed fact, before every doubt of its existence has been first removed. This subject well deserves a more full investigation from those who can be aided by more information, whether practical or scientific. [Appendix I.]

One of the circumstances will be mentioned, which appears most strongly opposed to the opinion which has been advanced. On the poor acid clay soil, of such peculiar and base qualities, which forms the subject of the 5th, 6th, and 7th experiments, gypsum has been sufficiently tried, and has produced not the least benefit, either be fore marling, or afterwards, Yet the growth of clover on this land after marling, is fully equal to what might be expected from the best operation of gypsum, Now if it could be ascertained that a very small proportion of either sulphuric acid, or of the sulphate of iron exists in this soil, it would completely explain away this opposing fact, and make

It is well known that gypsum has failed entirely as a manure on nearly all the land on which it has been tried in the tide-water district-and we may learn from various publications, that as little gen-chemical truths, may be offered to explain why eral success has been met with along the Atlantic coast, as far north as Long Island. To account for this general failure of a manure so efficacious elsewhere, some one offered a reason, which was received without examination, and which is still considered by many as sufficient, viz. that the influence of salt vapors destroyed the power of gypsum on and near the sea coast. But the same general worthlessness of that manure extends one hundred miles higher than the salt water of the rivers-and the lands where it is profitably used, are much more exposed to sea air. Such are the rich neutral soils of Curle's Neck, Shirley, Berkley, Brandon, and Sandy Point on James River, on all which gypsum on clover has been extensively and profitably used. On acid soils, I have never heard of enough benefit being obtained from gypsum to induce the cultivator to extend its use further than making a few small experiments. When any effect has been produced on an acid soil, (so far as instructed by my own experience, or the information of others,) it has been caused by applying to small spaces, comparatively large quantities-it the strongest support of my position. The suland even then, the effects were neither considerable, durable nor profitable, Such have been the results of many small experiments made on my own acid soils-and very rarely was the least perceptible effect produced. Yet on some of the same soils, after marling, the most evident benefits have been obtained from gypsum on clover. The soils on which the 1st and 10th experiments were made, at some distance from the measurements,) had both been tried with gypsum, and at different rates of thickness, before marling, without the least effect. Several years after both had been marled, gypseous earth (from the bed describled pp. 48, 49,) W spread at twenty bushels the acre, (which *Ag. Chem. p 141.

phate of iron has sometimes been found in arable soil,* and sulphuric acid has been detected in certain clays.† I have seen, on the same farm, a clay of very similar appearance to this soil, which had once contained one of these substances, as was proved by the formation of crystallized sulphate of lime, where the clay came in contact with calcareous earth. The sulphate of lime was found in the small fissures of the clay, extending sometimes one or two feet distant from the calcareous earth below, Precisely the same chemical

+Kirwan on Manures,

change would take place in a soil containing sul- | May 1834, on the field containing experiment 10. phuric acid, or sulphate of iron, as soon as marl The corn on the land marled four years before, was applied. The sulphuric acid, (whether free sprang up and grew with all the vigor and luxuor combined with iron) would immediately unite with the lime presented, and form gypsum, (sulphate of lime.) Proportions of these substances too small perhaps to be detected by analysis, would be sufficient to form three or four bushels of gypsum to the acre-more than enough to produce the greatest effect on clover-and to prevent any benefit being derived from a subsequent application of gypsum.

Since the publication of the foregoing part of this chapter, in the first edition, my use of gypsum, on land formerly acid, has been more extended, and the results have been such as to give additional confidence in the practice, and, indeed, an assurance of good profit, on the average of such applications. But still, as before, disappointments either total or nearly so, in the effect of such ap-so as by contrast more strongly to mark the gen plications, have sometimes occurred, and without there being any apparent cause to which to attribute such disappointment in the results.

riance that was expected from the appearance of increased fertility exhibited by the soil, as before described, (page 44.) About the 20th of May the change commenced, and the worst symptoms of the disease were seen by the 11th of June. From having as deep a color as young corn shows on the richest soils, it became of a pale sickly green. The leaves, when closely examined, seemed almost transparent-afterwards were marked through their whole length by streaks of rusty red, separated very regularly by what was then more of yellow than green-and next they began to shrivel, and die downwards from their extremities. The growth of many of the plants was nearly stopped. Still some few showed no sign of injury, and maintained the vigorous growth which they began with, eral loss sustained. The appearance of the field was such, that a stranger would have supposed that he saw the crop of a rich soil exposed to the In 1832, nine acres of the same body of ridge worst ravages of some destructive kind of insect: land above referred to, adjoining the piece on but neither on the roots or stalks of the corn could which the 1st, 2nd, 3rd and 4th experiments were any thing be found to support that opinion. Bemade, and more lately cleared, were sowed in clo- fore the 1st of August, this gloomy prospect had ver in the early part of 1831, on wheat. The improved. Most of the plants seemed to have next spring, French plaster was sowed at the rate been relieved of the infliction, and to grow again of a bushel to the acre, except on four marked ad- with renewed vigor. But before that time, many joining squares, each about one-third of an acre, were dead, and it was impossible that the others one of which was left without plaster, and the could so fully recover as to produce any thing apothers received it at the several rates of 2, 3, and proaching a full crop for the land. It has been 4 bushels to the acre. The whole brought a mid-shown in the report of the products of Exp. 10, dling crop, and was mowed for hay, except the what diminution of crop was then sustained-and square left without gypsum, which did not pro-that the evil was not abated by the next cultivaduce more than half as much as the adjoining tion. Still, neither of the diseased measured land where gypsum was applied at one bushel the acre. The product of the other pieces was slightly increased by each addition to the gypsum, but by no means in proportion to the increased quantity used: nor was the effect of the four bushels near equal to that formerly obtained, in several cases, from 20 bushels of gypseous carth taken from the river bank. Hence it seems, that it was not merely the unusual quantity of gypsum applied in this earth, which produced such remarkable benefit; and we must infer that it contains some other quality or ingredient capable of giving addi-grain. On very poor spots, from which nearly all tional improvement to clover.

CHAPTER XV.

THE DAMAGE CAUSED BY CALCAREOUS MA-
NURE, AND ITS REMEDIES.
PROPOSITION 5. Continued.

pieces has fallen as low as to its product before marling-nor do I think that such has been the result on any one acre on my farm, though many smaller spots have been rendered incapable of yielding a grain of corn or wheat.

The injury caused to wheat by marling is not so easy to describe, though abundantly evident to the observer. Its earliest growth, like that of corn, is not affected. About the time for heading, the plants most diseased appear as if they were scorched, and when ripe, will be found very deficient in

the soil has been washed, sometimes fifty heads of wheat taken together would not furnish as many grains of wheat. This crop, however, suffers less than corn on the same land-perhaps because its growth is nearly completed by the time that the warm season begins, to which the ill effects of calcareous manures seem confined.

When these unpleasant discoveries were first made, two hundred and fifty acres had already been marled so heavily, that the same evil was to be expected to visit the whole. My labors thus bestowed for years had been greatly and unnecesThe injury or disease in grain crops produced sarily increased-and the excess, worse than being by marling has so lately been presented to our no- thrown away, had served to take away that intice, that the collection and comparison of many crease of crop, that lighter marling would have additional facts will be required before its cause ensured. But though much and general injury can be satisfactorily explained. But the facts al- was afterwards sustained from the previous work, ready ascertained will show how to avoid the dan-yet it was lessened in extent and degree, and ger in future, and to find remedies for the evils already inflicted by the injudicious use of calca

reous manures.

The earliest effect of this kind observed, was in

sometimes entirely avoided, by the remedial measures which were adopted. My observation and comparison of all the facts presented, led to the following conclusions, and pointed out the course

by which to avoid the recurrence of the evil, and the means to lessen or remove it, where it had already been inflicted.

1st. No injury has been sustained on any soil of my farm by marling not more heavily than two hundred and fifty heaped bushels to the acre, with marl of strength not exceeding of calcareous earth.

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2d. Dressings twice as heavy seldom produce damage to the first crop on any soil-and never even on the after crops on any calcareous, or good neutral soil-nor on any acid soil supplied plentifully with vegetable matter.

3d. On acid soils marled too heavily, the injury is in proportion to the extent of one or all these circumstances of the soil-poverty, sandiness, and severe cropping and grazing, whether previously or subsequently.

4th. Clover, both red and white, will live and flourish on the spots most injured for grain crops, by marling too heavily. Thus, in the case before cited of land adjacent to the pieces measured in Exp. 10, and equally over-marled, very heavy red clover was raised in 1830, by adding gypsum, and which was succeeded by a good growth of corn, free from every mark of disease, in 1832.

5th. A good dressing of putrescent manure removes the disease completely, (see page 46.) All kinds of marl (or fossil shells) have sometimes been injurious-but such effects have been more generally experienced from the dry yellow marl, than from the blue and wet. It is possible that some unknown ingredient in the former may add to its hurtful power.

The cause of this disease is less apparent than its remedies. It is certain that it is not produced merely by the quantity of calcareous earth in the soil. If it were so, similar effects would always be found on soils containing far greater proportions of that earth. Such effects are not known to any extent, except on soils formerly acid, and made calcareous artificially. The small spots of land that nature has made excessively calcareous and sandy (as the specimen 4, page 19,) produce a pale feeble growth of corn, such as might be expected from a poor gravel-but whether the plants yield grain, or are barren, they show none of those peculiar and strongly marked symptoms of disease which have been described.

By calculation, it appears that the heaviest dressing causing injurious consequences, mixed to the depth of five inches, has not given to the soil a proportion of calcareous earth equal to two per cent. This proportion is greatly exceeded in our best shelly land, and no such disease is found there, even when the rich mould is nearly all washed away, and the shells mostly left. Soils of remarkable fertility from the prairies of Alabama and Mississippi have been shown (page 22) to contain from 8 to 16 per cent. of calcareous earth, all of which proportions were in the state of most minute division, and therefore most ready to produce this disease, if it could have been produced by the quantity of this ingredient. Very fertile soils in France and England sometimes contain twenty or thirty per cent. of calcareous earth. Among the soils of remarkable good qualities analyzed by Davy, one is stated to contain about The inferences to be drawn from these facts are, and another, which was eight-ninths of silievident. They direct us to avoid injury, by ap- cious sand, contained nearly of calcareous plying marl lightly at first, and to be still more cau- earth. Nor does he intimate that such proportions tious according to the existence of the circum- are very rare. Similar results have been stated, stances stated as increasing the tendency of marl from analyses reported by Kirwan, Young, Bergto do harm. Next, if the over-dose has already man, and Rozier, (page 46,) and from all, the same been given, to forbid grazing entirely, and to fur- deduction is inevitable, that much larger natural nish putrescent manure as far as possible-or to proportions of calcareous earth, than our diseased omit one or two grain crops, so as to allow more lands have received, are very common in France vegetable matter to be fixed in the land--to apply and England, without any such effect being proputrescent manures-and to sow clover as soon as duced. circumstances permit. One or more of these remedies have been used on most of my too heavily marled land—and with considerable, though not always with entire success, because the means for the cure could not always be furnished at once in sufficient abundance. Other persons, who permitted close grazing, and adopted a more scour ging rotation of crops, have suffered more damage, from lighter dessings of marl than mine.

But though the unlooked for damage sustained from this cause produced much loss and disappointment, and has greatly retarded the progress of my improvements, it did not stop my marling, nor abate my estimate of the value of the manure. If a cover of five hundred or six hundred bushels was so strong as to injure land of certain qualities, it seemed to be a fair deduction, that the benefit expected from so heavy a dressing, might have been obtained from half the quantity-if not on the first crop, at least on every one afterwards. That surely is nothing to be lamented. It also afforded some consolation for the evil of the too heavy marlings already applied, that the soil was thereby fitted to seize and retain a greater quantity of vegetable matter, and would thereby ultimately reach a higher degree of fertility.

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From the numerous facts of which these are examples, it is certain that calcareous earth acting alone, or directly, has not caused this injury: and it seems most probable that the cause is some new combination of lime formed in acid soils only-and that this new combination is hurtful to grain under certain circumstances which we may avoid—and is highly beneficial to every kind of clover. Perhaps it is the salt of lime, formed by the calcareous manure with the acid of the soil, which not meeting with enough vegetable matter to combine with and fix in the soil, causes by its excess, all these injurious effects.

CHAPTER XVI.

RECAPITULATION OF THE EFFECTS OF CAL-
CAREOUS MANURES, AND DIRECTIONS FOR
THEIR MOST PROFITABLE APPLICATION.

PROPOSITION 5. Continued.

From the foregoing experiments may be gathered most of the effects, both injurious and

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