Hav so generally done with bones,) have been so suc- | stone rocks are charged with carbonate of lime, cessful, that manufactories of what is called super- those from magnesian limestone or dolomites with phosphate of lime have sprung up, in which consid- sulphate of magnesia, from red sandstone formaerable capital is invested, greatly to the profit tions with salt and gypsum, and from the Oxford of both makers and consumers. There are at pres-clays with sulphate and carbonate of lime. ent many persons engaged, and in many countries, ing performed its part of the appointed task, chemin searching for these nodules, wherever deposits istry now hands over the practical agriculturist to like those of the crag or greensand rocks occur, descriptive geology; and she forthwith points out and in inquiring whether other geological forma- to him the places where these different varieties tions may not also contain them—so that it is im- of rock occur; so that he may judge in what manpossible to assign a limit to the general gain to ner particular waters are likely to affect his soils, agriculture which may ultimately follow from this to influence his crops, or to modify the action of one investigation. the mixtures he applies to aid their growth. But the reciprocating sciences do not stop here. Geology then takes the initiative: "My greensand beds and my crag deposits are often rich in fossil phosphates. Will not the waters which pass through them be comparatively rich in phosphates, also and may not such waters materially influ An examination of the beds of marl, in which the greensand nodules are frequently found, has proved that they also contain phosphate of lime, sometimes in considerable abundance, distributed through their entire mass. Immediately on such discovery, these marls rose in estimation. People now found out the reason of their having been ence the agricultural value of the adjoining lands?” often dug up by the neighboring farmers to lay | upon their land. Where they had never been so used, their employment was recommended; and the peculiar and well recognized fertility of certain soils, which either rested on, or were formed from, or adjoined these marl beds, was at length satisfactorily accounted for. Thus chemistry is again set to work, and arrives at new results; the pecuniary profit of which the unconscious farmer by and by steps in to reap, without ever dreaming that the labor of others, either manual or mental, had been concerned in placing them within his reach. Again: "Some of my clays," says Agriculture, In many other districts marls occur, by which" are greatly improved by the use of lime, while the adjoining lands have been long known to be improved. Such are the marls which underlie the sandy surface of northern Norfolk, and which gave Mr. Coke the chief means of redeeming from their poverty-stricken state the thousands of acres he lived himself to see enriched. Such, also, are the marls which, in the form of nests and irregular layers of chalk drift, underlie the immediate surface of a large portion of the counties of Huntingdon and Bedford. Are there any phosphates in these marls! Do those of Norfolk owe any of their fertilizing virtue to the presence of mineral phosphate? These are questions which previous experience must now suggest to practical agriculturists; for science is a mistress who, in conferring one favor encourages her suitors to look for more, and shows them the way in which they are most likely to succeed. on others no perceptible good has followed from it."-" Where are they respectively situated?” asks Geology. Informed on this point, Geology observes, that "the London, the Plastic, and the Weald clays, which lime improves, are of a different geological age from the Oxford clay and its derivative soils, on which it is often applied without any sensible effect." Both then turn to Chemistry to learn the cause of the difference in question. And her analysis speedily tells them that the Oxford clay often contains one fourth of its weight of finely divided chalky matter, or carbonate of lime, and requires, therefore, no further addition of what is truly understood to be a necessary ingredient of every fertile soil. In conclusion, an intelligent interpretation of the experience of the past is full of instruction on the course most profitably to be followed for the future. The Use of Lime in Agriculture is the subject to which one of the books we have placed at the head of this article is especially devoted; and from the many illustrations this work affords, we will select one of a large and general kind. But, in many other instances, chemistry and geology cooperate for the benefit of agriculture. The former says: "Springs which flow through the soil, or which naturally descend from higher ground, exercise the greatest influence upon veg etation. The substances which they hold in solu- It may be laid down as a universal principle, tion are sometimes the cause why particular appli- that in our climate a certain proportion of lime in cations, otherwise most useful, are in certain cases the soil is necessary to bring out its full producunnecessary, or even prejudicial." It therefore tive power. But as soils are generally derived analyzes the waters. This is one of the duties from the rocks on which they rest-or from others which scientific agriculture now requires from at no great distance, geologically considered-the chemistry, as much as boards of health. Accord-proportion of lime these rocks contain is a suffiingly, the complacent science compares the nature cient indication of the proportion which may be of the minerals and rocks through which they expected in the soils. That is to say, soils will have come; when it finds that waters which trav- not, in general, contain more lime than the rocks erse aqueous rocks contain soluble silicates-that to which they belong; if the one is poor in lime, mica slate springs contain silica and magnesia- the other is likely to be poor also. Hence the that the streams which so often gush from lime- analysis of the rocks of a district becomes of im portance to agriculture, as an index not only of the natural fertility of its soils, but also of the methods to be adopted in order to increase their productiveness. And, as rocks of the same kind often extend over very large areas, and are repeated at intervals more or less distant over the entire surface of the globe, it must frequently happen that the results deduced from a chemical examination of the rocks of one district will prove true of those of many other districts-the general composition of the natural soils will be the same, and the same practical conclusions will apply to them all. Among other rocks, those commonly known by the names of whinstone and trap rocks, occur abundantly in Scotland; and the fertility of the soils formed from them is owing, in part, to the large per centage of lime which they contain. Again, the absence of lime in granitic rocks is one reason for the general unproductiveness of soils formed from them. The inferences of which we are speaking, must of course hold good of all other districts in which these several rocks occur, and which possess the same general composition. But a more interesting case is that of the slaterocks, (formerly called Grauwacke, and now distinguished as Silurian,) which cross the island from the Mull of Galloway to St. Abb's Head. This is a tract of poor country, cold and inhospitable, and, as yet, little frequented by agricultural improvers. A suite of specimens from the rocks of this district has been analyzed, with the following result: "The proportion of lime in the different beds of this formation, in the South of Scotland, is small. In general, as a consequence, the soils formed from them will be deficient in lime. In this the reason appears why, in practice, it has been found that the addition of lime is an almost indispensable preliminary to any successful and permanent improvement of the surface where these rocks prevail." Over this large breadth of country no available beds of limestone are at present known to exist; and from our own observations on its western shores, improvement appears to have begun along the borders of the sea, and in the neighborhood of ports to which lime could be imported, as from Cumberland, from the Isle of Man, or from Ireland—and to have spread inland as far and as fast as roads were made to allow of its being easily transported into the interior. It is surely a merit in chemical science to have shown why such a practice has succeeded; and to have assigned a reasonable ground for recommending its general extension as almost indispensable, in a region like this, to the successful development of its agricultural capabilities. ical age; and thus practical precepts like the above, when once recorded in our books, become part of the stock of chemico-agricultural truth, which is common to, and may be economically applied in, every country of the globe. Take, for example, the memoir of Professor Dumont, of Liège, upon the Ardennes-a wellknown tract of thinly peopled and poorly productive country, which stretches north-east from Mezieres, in France, to the Rhine, at Bonn, and according to some geologists, far into Westphalia. In reading the description of his Terrain Ardennais, one could almost fancy he was treating of the zone of southern Scotland to which we have just been referring. * The "The greater part of the soil," he says, "is still barren. * * Immense tracts are covered only with heath, fern, broom, and forests. slaty parts present, in general, only deserts, dry or wet, covered with heath or with peat, according to their position. It is distinguished from the neighboring countries by the almost total absence of lime. On its south-eastern extremity the plateau of the Ardennes is covered with a layer of clay, overlying chalk marl, which ameliorates the soil, and changes its character." The portion of the Ardennes to which the above description relates, is nearly of the same geological age as that of the southern slate country of Scotland; and the first steps towards agricultural improvement must be the same in both. The artificial application of lime has accordingly been found most advantageous in the one instance; while the natural admixture of marl in the other is seen to change and fertilize the soil. The researches of modern science, therefore, do not leave a doubt concerning the only prudent economical treatment of such a case. But there is a host of lesser questions of a practical kind, in connection with the use of lime, on which chemistry has thrown a useful light. Every one at all conversant with the history of agriculture is aware of the immense sums which are annually expended in the purchase of this substance; of the numerous misapplications of it which are constantly made; and of the injury which has resulted from such misapplications in every country of Europe. Hence the different opinions entertained concerning the purposes which lime serves in the land; the quantity which ought to be administered; the frequency with which it should be repeated; the amount of compensation which ought to be given to a retiring tenant who has limed his farm; and the ridiculous stipulations, in regard to all these points, which have made their way into leases and farm agreements. Some of the greatest practical mistakes in the use of lime appear to have arisen from supposing that it acts primarily as a manure, properly so called, and that it is capable, in good husbandry, We have said that the practical benefit of such a deduction is not limited to the tract of country in which it has primarily been made. It extends to all countries similarly constituted, or in which of taking the place of a manure. In describing the the rocks have the same general mineral and chem- treatment to which he means to subject his land, a ical characters. This, with certain exceptions, is farmer will say that he means " to lime or manure' very much the case with rocks of the same geolog-| his land at such and such intervals; leases bind tenants" to lime or manure" within certain fixed | which follow from burning limestones and slaking periods; and straw or hay is allowed to be sold off burned lime is, that the lime itself, being naturally the farm on condition that so much lime or manure reduced, or falling to an impalpable powder, can be brought on to the farm in return. Chemistry not only be extensively spread over and minutely has shown the erroneous nature of the opinions mixed up with the soil, but is in a condition, also, which gave rise to such practices and prescrip- to act more readily upon those ingredients of the tions; how evil must follow from them; of what soil which it is intended to influence. Of this special kind this evil must be; and yet that, with minute subdivision the mineral phosphate contained a use of lime as liberal as before, the recurrence in the lime necessarily partakes, by which means of such evils may be prevented. This, of itself, it goes further than a larger quantity applied in the is a sufficiently intelligible money gift conferred by grosser form of bone-dust, or in any of the other science upon the rural community. forms in which it has hitherto been usually laid on the land. Again, limestones are of use to the farmer, only according to the kind and amount of action they exercise on certain soils and crops. Experience had long shown this. The ancient Greek and Roman writers were aware of it; and, in our home districts, wherever a choice of limes exists, the farmer prefers one variety to another, because of a difference, real or fancied, in their effects upon his land. It was something to ascertain the nature and cause of these diversities; to explain, by analysis, the chemical differences between the limes from which such different effects followed; and thus to connect observation and science. But when practical men are at issue among themselves -when they cannot agree on the unknown qualities of a new variety of lime-when a prejudice exists against all the limes of a given district, in consequence of the mischief done by the lime of some particular lime-beds, or lime-works-chemistry has rendered the parties a still more obvious service. To the manifest advantage of both limeburner and farmer, it is able rigidly to fix the absolute and relative values of each variety, and in every locality. It is among the interesting consequences, by which all minute researches into nature are at once rewarded and encouraged, that the pursuit of one object almost invariably leads to the unlooked-for discovery of others—as the high road to a great city leads us past many mansions, opens up beautiful prospects, and brings us now and then to cross-roads where finger-posts indicate the way to places of which the very existence was previously unknown to us. The study of limestones, with a view to economical purposes only, would furnish us with instances in point. We will mention one of them, chiefly because of its close relation to the illustration we have already drawn from the mineral phosphates of the greensand and the crag. In noticing these phosphates, we explained how essential they were for the production of bone in animals, and that to all plants they were a necessary of life; that therefore they must exist, to a certain extent, in the soil from which plants draw their mineral food; and that they constituted most valuable manures, accordingly, whenever any deficiency in respect of them had to be supplied. Now, in analyzing limestones and burned lime, it has been discovered that a trace of this phosphate of lime exists in them all. In some it is merely a trace, in others it amounts to a sensible and practically useful proportion. One of the main benefits In so far, therefore, as they contain phosphate of lime, applications of quick-lime really act directly as manures; and since in some limes, even of the same geological age and position, this phosphate is six times more abundant than in others, we have arrived at an intelligible cause of the difference which different limes present, in the character of manures. To a soil naturally deficient in phosphates, and in districts where the artificial application of phosphates is unknown, the use of one of these limes rather than the other must be attended with important consequences. Not only are such considerations economically useful to the practical man-in showing him how and what to select, and the relative money values of this or that variety-but they explain why in some places land will bear and pay for liming much longer than in others; why some soils remain long fertile without any artificial addition of phosphates; and how in some localities the rearing and breed-" ing of stock, and the reaping of yearly corn, may be continued from generation to generation without apparent injury to the land. ire. One example, among the numerous perplexities of the farmer, we may venture to specify, as the statement we have just made enables us to explain it. Dairy husbandry has long prevailed in CheshNow it has been ascertained that every milk cow robs the land annually of as much phosphate of lime as is present in eighty-two pounds of bone-dust. From being thus gradually despoiled of this valuable mineral, the Cheshire pastures have become less rich in nutritious herbage; and hence the peculiar benefit derived from boning them—a practice now so extensively and profitably introduced. But the Cheshire farmers found that after their land had been limed, bones were, to a great degree, a failure; while, conversely, some observed that, after a heavy boning, lime was not so immediately remunerative. The analysis of the soils and of the limes usually applied in that county, cleared up both appearances. The soil being poor, both in lime and in phosphorie acid-the two ingredients of bone-earth—was less grateful for the after application of lime, because the bones had already given it a certain dose of this substance; and, on the other hand, the soil was less remarkably affected by bones, because of the notable quantity of phosphoric acid which lime of a certain quality had previously conveyed to it. The money value to practical men of an accu more cautious practitioners warned their brethren by their own experience; which the more complete and correct deductions of science have since confirmed and explained. Manures containing nitro rate knowledge of calcareous substances, is strikingly illustrated by the fact that a few years ago patent was obtained for the process of burning the shell-sand (sea-sand mixed with fragments of shells) which occurs so abundantly on the coasts of Corn-gen are available in all soils in promoting luxuIwall and of the Western Isles. Plausible statements concerning the value of this burned sand as a manure were circulated and believed ; and much money was wastefully expended in the purchase of it. The publication of an analysis of its contents by a competent authority at once destroyed the charm, and protected the farmer from further imposition at least, in this particular. riance of growth; but the solubility of such substances as saltpetre and common salt, is one of the very properties on which their immediate and successful action upon plants depends. It required the successive crops of two harvests, however, to convince the parties of their imprudence. These insoluble manures have now disappeared from the British markets; purely mineral mixtures, however, still retain an uncertain and temporary hold upon public favor. But two facts are sure to banish them from the list of fertilizing substances, which can generally be relied upon in all soils and for all crops. These are, first, that plants do really obtain and require from the soil certain forms of organic food; and, secondly, that all naturally fertile soils do contain a sensible proportion of such organic matter. Suppose a soil to be deficient in this organic matter, a purely mineral manure, however compounded, cannot supply it; and the application of such a manure upon such soils must be followed by a failure. But let it be naturally rich in such matter, and the mineral mixture may possibly be applied with a profit. It must appear, therefore, how economically important it is to practical agriculture, that science should be steadily and cautiously prosecuted Even the theoretical views of men of science in regard to fertilizing substances have often a direct bearing upon practice. In England we are fond of novelty; and we frequently yield our assent to scientific opinions when given forth with sufficient confidence, and expend our money in obedience to them. It is far from true that, by despising and neglecting science himself, the practical farmer escapes from its influence. The speculations of the men he underrates affect in an important degree the profits of his class notwithstanding. Of this we can now give a striking illustration. Analysis in the laboratory of the chemist had ascertained that ammonia exists in the atmosphere to a certain extent, and that plants always contain a quantity of mineral matter, derived from the soil. In the mean time experience had found in the field, that mineral substances, such as saltpetre, nitrate of soda, gypsum, common salt, &c., were often ex-in its behalf; and that the best safeguard of the tremely beneficial when applied alone to our growing crops. Upon these facts, Liebig ventured boldly to propound two opinions-first, that the application to the soil of substances containing nitrogen was wholly unnecessary, because the ammonia of the atmosphere was sufficient to supply all they required of this ingredient ;* and next, that a proper admixture of mineral substances was all that a manure need contain in order to render the land fertile for any crop. Thus mineral manures were strenuously recommended-alone, and for all soils. Proceeding upon the assumption that the rains are continually washing from the soil its mineral constituents in proportion as they became dissolved, he next concluded that the action of his mineral mixtures would be more permanent and efficient if, by some chemical process, they were rendered more sparingly soluble in water. Hence the origin of the patent manures called after his name. They profess to contain all the substances which the crops for which they are intended can require from the soil, and to contain them in a state in which the rains would not easily remove them. The love of novelty, assisted by faith in a deservedly high name, has caused thousands of pounds to be spent in the manufacture of these manures, and many more thousands in the purchase of them; while even larger sums have been lost by the more or less partial failure of the crops they were intended to improve. It was in vain that *The reader is, probably, aware that ammonia consists of the two gases, nitrogen and hydrogen. farmer's pocket is a knowledge of the scientific principles on which his art eventually rests. Without that knowledge, however much he may undervalue it, he is at the mercy of every rash hypothesis, and may be induced to expend his money upon the nostrums of mere money-seeking quack-salvers. Thirdly. The Dairy and the feeding of stock form another general branch of husbandry, to which science has been of no less positive use, than to the two departments which, in the preceding pages, have principally engaged our attention. Indeed, this must have already struck the reader, from what we have said upon the subject of food, and from the brief allusion we have made to the specially exhausting effects of the dairy husbandry upon the soils of Cheshire, and the mode of repairing them which chemistry supplies. In the case of dairy farms, the chemical examination of milk drawn from different animals, and under very varying circumstances, has provided us with a body of facts which admit of numerous profitable applications. Thus it is ascertained that the curd and the butter of milk correspond to the muscle and fat of the animal. Hence the reason why good milkers are generally poor in condition, and why the milk falls off when they begin to fatten. And as the curd and butter, like muscle and fat, are derived immediately from the food which the cow eats, and as we know the respective sources of these, we can in some measure control the proportion of each which the milk shall contain. If it is to be rich in butter, we select a food which, like linseed or linseed cake, is naturally rich in oil, or we mix other cheaper forms of fatty matter directly with the ordinary food. If curd (or cheese) is our object, we give food, such as beans and cabbage, which analysis has shown to be rich in gluten, or in some other of the socalled protein compounds. And if, while we are rearing calves, we wish to sell the milk which is high in price, we can, from our knowledge of the composition of milk, and of the various kinds of food at our command, provide an artificial substitute which will serve exactly the same purpose in feeding and rearing the calf, and yet cost less money than the sale of the milk brings in. more nutritious in its recent than in its dry state, and how the loss in drying is to be prevented— why new corn, wheat, beans or oats, are unwholesome food for a horse-why new oats make him greasy-why kiln-dried oats affect his kidneyswhy hunters keep their condition better on the common Angus than on the potato oat, and why the meal of the former variety is a better support for the Scottish ploughman ;-these are all questions which chemistry has taken up, and has succeeded in fully solving-or is confident in its ability to solve-and the least informed in practical matters must see how the solution of every one of these problems more or less directly affects the pecuniary interests of the holder or possessor of land. We might enumerate scores of other questions of a similar kind, which only scientific investigation can answer; and, as in the preceding part of this paper, we might illustrate, by numerous examples, the direct money value of such researches. But our limits compel us to refrain. Our limits do not permit us to introduce other detailed illustrations of the uses of chemistry to the dairy. Why butter is hard or soft-how its quality is to be improved or maintained—how it is to be best preserved—why it becomes rancid, and how such a change is to be prevented—what takes place during the process of churning, what during that of natural or artificial curdling-what is the Fourthly. There is a fourth subject, not withnature of rennet, and how it acts-in what man-out its share of economical interest to the farmer, ner we can prepare an artificial substitute for ren- on which the volumes before us throw considernet which shall be easily made and constant in its able light. All our manufactures produce Waste composition, quality, and effect-how cheese should or Refuse materials, to which the progress of be salted-what kind of salt employed-why dif- science gives a new value by discovering for them ficulties occasionally arise in the storing of cheese new uses. "Can any of them be of use to me?" how they are to be overcome or prevented ;- Agriculture demands; "for what purposes can I these, and many similar questions, are treated of employ them? and what price ought I to pay for in the works before us of the latest date. The them?". It is to Chemistry that we must suppose mere enumeration of them is all that can be wanted these questions put; for it is chemical analysis to demonstrate how very extensive, and how prac- alone, which has the power of making a satisfactically and economically useful, are the applica- tory reply. tions of chemical science to the pursuits of the dairy farmer. When the principles on which the improvement of land is based are once fully understood when the elementary substances are known, which are necessary to render a soil fertile, or to make a crop grow healthily and with luxuriance, and also their opposites-all we require to learn of any substance, with the view of determining whether or not it will form a useful application to the land, is, what it consists of, and in what state of combination its constituents exist. We can then pronounce with certainty whether it can be of any use to vegetation, and upon what soils and crops, and in what quantities, it is likely to produce the most beneficial effects. Chemical analysis, therefore, determines the value to the farmer of the refuse of the manufacturer, and upon such inquiries it has expended considerable time and minute attention. In our climate, the rearing and feeding of stock is scarcely second in importance, as a source of rural profit, to the growing of corn; and there are many who think that, under our altered fiscal regulations, it must and ought to become the more important of the two. It is certain that, so far as climatic conditions go, green crops appear to be more natural productions of our rainy islands than crops of corn. But, for the feeding of animals, science has done at least as much as for the culture and fertilizing of the land. The several purposes which are promoted by food have been investigated-what it must be fitted to serve if it is to keep an animal in a healthy condition-what is the composition of each of the more common kinds of food on which animals are nourished-how The determination of such values involves two what is given to the animal must be adapted to its considerations—a chemical and an economical one. period of growth, to the purposes for which it is The chemical inquiry is-Does this substance confed, (for work, for beef or mutton, for milk, fortain anything which is likely to benefit the soil or growth, &c.,) and to the conditions of tempera- the crop? and, further, What soils and what crops? ture, &c., in which it is placed-why one kind of food will keep an animal in condition for hard or fast work, while another makes him heavy, sleek, or fat-why the same kind of root crops are not always equally nutritive, what power we possess to increase their natural nutritive quality, or, when this quality is lower than usual, to bring it up to the natural standard—why green herbage is The economical inquiry is, What is the worth of the refuse, calculated at the market price of the useful ingredients it contains? and, further, What is its worth to this or that farmer living at this or that distance from the manufactory, and having to transport it thither? For instance, the refuse substance, though possessed of a certain money value on the spot where |