On the fertilizing Effects of Gypsum in the United States of America; with a View to elucidate its mysterious Operation, and to extend its Benefits to England, and other Parts of the British Dominions. By A. FOTHERGILL, M. D. F. R. S. Hon. Member of several Med. Phil. and Agric. Societies. From the COMMUNICATIONS to the BOARD of GYPSUM, the alabaster of the antients, now commonly termed sulphat of lime, or plaster of Paris, by the moderns, is found in various parts of the world. England it is found in Derbyshire, Somersetshire, and Devonshire, and probably exists in many other parts of England, and also of Ireland. It is a compound fossil, consisting of sulphuric acid 30, pure calcareous earth 32, water 38, according to M. Chaptal; and it requires 450 times its own weight of boiling water to dissolve it. By calcination it loses 20 per cent.; and in that state, when incorporated with water, forms the well-known composition for modelling and statuary, and yields with sand a cement impervious to water, when applied instantly at the time of mixing. It is precipitated by fixed alkalies, but not by the volatile in a caustic state. When pure it does not effervesce with acids. It powerfully promotes putrefaction, whereas lime resists it, although it dissolves organised bodies. Of gypsum there are five species, which vary according to their purity and degree of neutralization; hence the analysis of Bergman, Chaptal, and other chemists, differ Ff 2 as as a as to the proportion of the respective ingredients manure, the fibrous or laminated sort is deemed the best. It assumes various colours from other minerals : it is often semi-transparent, very brittle, and may be scraped with the nail of a finger. From the above properties, it would seem a very unpromising substance for a manure; and yet, what is remarkable, most plants, on analysis, yield gypsum. Nor is this more wonderful than that they should be able to digest carbon, nay even silex, or real flint, supposed to be totally insoluble in water! How little do we yet know of the mysteries of the vegetable economy! In the year 1768, the Rev. Mr. Meyer, of the canton of Bern, by a fortunate accident, discovered the fertilising power of gypsum, and liberally disclosed the secret to the neighbouring farmers. To their great surprise, experiments soon convinced them of its efficacy, which they considered as little short of magic. Its fame spread through Germany, and at length reached their German friends in Pennsylvania, where Judge Peters, after subjecting it to various trials on different soils, candidly communicated to the public the result of his experiments. This first brought it into notice in America, and contributed not a little to extend its benefits to the remotest parts of the Union. From his information till the year 1797, and from that of others till the present time, may be collected the result of what is yet known on the subject, and which I shall endeavour to comprise in the following sketch, so far at least as to comprehend the principal leading facts. Although gypsum has been discovered in the state of New York, and probably abounds in many other districts, yet it continues to be imported in large quantities from Nova Scotia, some from France, though per haps haps chiefly as ballast, as it can be bad at half a dollar a bushel*. Both sorts are thought to answer equally well; yet such samples as undergo, on exposure to heat, the quickest ebullition, and emit the strongest sulphurous fumes, are generally preferred. Such is the increasing demand, that it is sometimes carried from the wharfs on the banks of the Delaware, above 150 miles by land carriage. It is prepared for use by first pounding it into very small pieces, and then grinding it in a mill, so as to measure 20 or 25 bushels per ton. The mill-stones employed for this purpose, it is hoped, will not in future be used for grinding grain. For want of this precaution, two fine horses are supposed to have perished; large calculous concretions having been afterwards found in their intestines. Hard waters, which are considered so injurious in cases of stone and gravel, owe their hardness to invisible particles of gypsum, and which, on evaporation of the water by boiling, deposit those stony incrustrations, so often found in tea-kettles. To a similar origin may be referred those gypsous petrifactions and sparry crystals found in subterraneous caverns, and which serve to adorn our grottos. But to proceed-gypsum affords a cheap and durable manure, and of easy management. When used freely, after the rate of five or six bushels to an acre, its fertilizing effects are found to last six or seven years, though sometimes not very apparent till the third year. Some find it answers better in the proportion of a single bushel every year, with an entire intermission every fourth *The quantity imported per annum into this port alone has been computed to amount to 12,000 tons a proof of the estimation in which it is held. Thus it is become an article of commerce, as well as of agriculture and statuary.` year. year. Others think two bushels annually but a small proportion; but this will vary according to the state of the soil. The finer the gypsum is powdered the more speedy is its operation, but the less durable. Its action, being modified by the weather, and sundry minute circumstances, appears mysterious, though its effects are visible, "Causa latet, vis est notissima.” The mode of using it, is to moisten the seed-grain with water, and then roll it in the pulverised gypsum, which is called coating it; in which state it is sown in the ordinary way. When used as a top dressing, it is also strewed with the hand, as in sowing grain, which is a very uncertain method. Were the drill husbandry generally adopted in this country it would not only facilitate the labour, but disseminate the coated grain, with the utmost regularity, and produce superior crops, with a much smaller proportion of seed, which would soon amply compensate the expence of the machine, and introduce a capital improvement in cultivation. Some experienced agriculturists allege that gypsum ought not to be applied during the cold of winter, while plants are in a torpid state, but should have the first sprinkling when the young shoots begin to appear, and a second when vegetation is more vigorous, but not too late in the season, lest the gypsum should injure the grazing cattle. Others, however, prefer the winter season, and apply this manure even while the ground is covered with snow. It is generally believed, though not without some exceptions, that gypsum fails near the sea, and in all cold clayey soils, like that at Mount Vernon, which explains why General Washington's experiments, though varied in different modes, and proportions, from one to twenty bushels per acre, proved uniformly unsuccessful. A moist climate, a marshy soil, and one abounding with iron ore, have also been deemed unfavourable. Judge Peters, after twenty-five years experience, informs us that the soils to which it is most congenial, are the light, dry, sandy, and loamy; and that on strong clay it yields no benefit. That it succeeds best after stable manure and green crops ploughed in. That it promotes the growth of leguminous crops, also the plants of kitchen gardens, fruit trees, Indian corn, the various grasses, but particularly red clover. That it should be applied from the beginning of February till April, and if the weather be foggy or hazy it succeeds, the better. That as a top dressing, it is most beneficial in spring, when plants are active, and imbibe their food. That it answers well after lime and alkaline manures; and that cattle seem to prefer the herbage above that which is raised from other kinds of compost. That it speedily converts straw and other vegetable substances into manure; and, by quickening the growth of grain, stifles and overpowers weeds. ་ Chancellor Livingston, from his experiments, draws the following inferences. 1st. That gypsum in small quantities produces no visible effect on wheat or rye. 2d. That it is beneficial to Indian corn and flax on dry sandy land. 3d. That it is peculiarly adapted to clover in dry soils, and even in wet soils in a dry season. 4th. That crude limestone pulverised has similar effects with gypsum, but requires to be applied in nearly double quantity. 5th. That sea air is unfavourable to gypsum. Mr. Ely informs the Society of Agriculture at Boston, that gypsum after stable manure answered best. That having |