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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 profil 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. Havent 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 be applies to aid their growth. An examination of the beds of marl, in which But the reciprocating sciences do not stop here. the greensand nodules are frequently found, has Geology then takes the initiative : “My greenproved that they also contain phosphate of lime, sand beds and my crag deposits are often rich in sometimes in considerable abundance, distributed fossil phosphates. Will not the waters which pass through their entire mass. Immediately on such through them be comparatively rich in phosphates, discovery, these marls rose in estimation. People also ? and may not such waters materially influnow 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 Thus chemistry is again set to work, and arrives upon their land.
Where they had never been so at new results; the pecuniary profit of which the used, their employment was recommended ; and unconscious farmer by and by steps in to reap, the peculiar and well recognized fertility of cer- without ever dreaming that the labor of others, lain soils, which either rested on, or were formed either manual or mental, had been concerned in from, or adjoined these marl beds, was at length placing them within his reach. satisfactorily accounted for.
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 on others no perceptible good has followed from improved. Such are the marls which underlie it.”—“Where are they respectively situated ?" the sandy surface of northern Norfolk, and which asks Geology. Informed on this point, Geology gave Mr. Coke the chief means of redeeming from observes, that “ the London, the Plastic, and the their poverty-stricken state the thousands of acres Weald clays, which line improves, are of a differhe lived himself to see enriched. Such, also, are ent geological age from the Oxford clay and its the marls which, in the form of nests and irregu- derivative soils, on which it is often applied withlar layers of chalk drift, underlie the immediate out any sensible effect.” Both then turn to Chemsurface of a large portion of the counties of Hun- istry to learn the cause of the diference in questingdon and Bedford. Are there any phosphates tion. And her analysis speedily tells them that in these marls? Do those of Norfolk owe any of the Oxford clay often contains one fourth of its their fertilizing virtue to the presence of mineral weight of finely divided chalky matter, or carbonphosphate? These are questions which previous ate of lime, and requires, therefore, no further experience must now suggest to practical agricul- addition of wbat is truly understood to be a necesturists ; for science is a mistress who, in confer- sary ingredient of every fertile soil. In concluring one favor encourages her suitors to look for sion, an intelligent interpretation of the experience more, and shows them the way in which they are of the past is full of instruction on the course most most likely to succeed.
profitably to be followed for the future. But, in many other instances, chemistry and The Use of Lime in Agriculture is the subject geology coöperate for the benefit of agriculture. to which one of the books we have placed at the The former says : “Springs which flow through head of this article is especially devoted ; and the soil, or which naturally descend from higher from the many illustrations this work affords, we ground, exercise the greatest influence upon veg. will select one of a large and general kind. 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 reslor 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-l analysis of the rocks of a district becomes of importance to agriculture, as an index not only of|ical age; and thus practical precepts like the the natural fertility of its soils, but also of the above, when once recorded in our books, become methods to be adopted in order to increase their part of the stock of chemico-agricultural truth, productiveness. And, as rocks of the same kind which is common to, and may be economically often extend over very large areas, and are repeated applied in, every country of the globe. at intervals more or less distant over the entire Take, for example, the memoir of Professor surface of the globe, it must frequently happen Dumont, of Liège, upon the Ardennes—a wellthat the results deduced from a chemical examina- known tract of thinly peopled and poorly protion of the rocks of one district will prove true of ductive country, which stretches north-east from those of many other districts—the general com- Mezieres, in France, to the Rhine, at Bonn, and position of the natural soils will be the same, and according to some geologists, far into Westphalia. the same practical conclusions will apply to them In reading the description of his Terrain Ardenall.
nais, one could almost fancy he was treating of Among other rocks, those commonly known by the zone of southern Scotland to which we have the names of whinstone and trap rocks, occur just been referring. abundantly in Scotland ; and the fertility of the “ The greater part of the soil," he says, “ is soils formed from them is owing, in part, to the still barren.
Immense tracts are covered large per centage of lime which they contain. only with heath, fern, broom, and forests. The Again, the absence of lime in granitic rocks is one slaty parts present, in general, only deserts, dry reason for the general unproductiveness of soils or wet, covered with heath or with peat, according formed from them. The inferences of which we to their position. It is distinguished from the are speaking, must of course hold good of all other neighboring countries by the almost total absence districts in which these several rocks occur, and of lime. On its south-eastern extremity the which possess the same general composition. plateau of the Ardennes is covered with a layer of
But a more interesting case is that of the slate- clay, overlying chalk marl, which ameliorates the rocks, (formerly called Grauwacke, and now dis- soil, and changes its character.” The portion tinguished as Silurian,) which cross the island of the Ardennes to which the above description from the Mull of Galloway to St. Abb's Head. relates, is nearly of the same geological age as This is a tract of poor country, cold and inhospita- that of the southern slate country of Scotland ; ble, and, as yet, little frequented by agricultural and the first steps towards agricultural improveimprovers. A suite of specimens from the rocks ment must be the same in both. The artificial of this district has been analyzed, with the follow- application of lime has accordingly been found ing result : “ The proportion of lime in the dif- most advantageous in the one instance ; while the ferent beds of this formation, in the South of Scot- natural admixture of marl in the other is seen to land, is small. In general, as a consequence, the change and fertilize the soil. The researches of soils formed from them will be deficient in lime. modern science, therefore, do not leave a doubt In this the reason appears why, in practice, it has concerning the only prudent economical treatment been found that the addition of lime is an almost of such a case. indispensable preliminary to any successful and But there is a host of lesser questions of a permanent improvement of the surface where these practical kind, in connection with the use of lime, rocks prevail.”
on which chemistry has thrown a useful light. Over this large breadth of country no available Every one at all conversant with the history of beds of limestone are at present known to exist ; agriculture is aware of the immense sums which and from our own observations on its western are annually expended in the purchase of this subshores, improvement appears to have begun along stance ; of the numerous misapplications of it the borders of the sea, and in the neighborhood which are constantly made ; and of the injury of ports to which lime could be imported, as from which has resulted from such misapplications in Cumberland, from the Isle of Man, or from Ire- every country of Europe. Hence the different land—and to have spread inland as far and as fast opinions entertained concerning the purposes which as roads were made to allow of its being easily lime serves in the land; the quantity which ought transported into the interior. It is surely a merit to be administered; the frequency with which it in chemical science to have shown why such a should be repeated; the amount of compensation practice has succeeded ; and to have assigned a which ought to be given to à retiring tenant who reasonable ground for recommending its general has limed his farm; and the ridiculous stipulaextension as almost indispensable, in a region like tions, in regard to all these points, which have this, to the successful development of its agricul- made their way into leases and farm agreements. tural capabilities.
Some of the greatest practical mistakes in the We have said that the practical benefit of such use of lime appear to have arisen from supposing a deduction is not limited to the tract of country that it acts primarily as a manure, properly so in which it has primarily been made. It extends called, and that it is capable, in good husbandry, 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 Again, limestones are of use to the farmer, only the land. according to the kind and amount of action they In so far, therefore, as they contain phosphate exercise on certain soils and crops. Experience of lime, applications of quick-lime really act directly had long shown this. The ancient Greek and as manures; and since in some limes, even of the Roman writers were aware of it; and, in our home same geological age and position, this phosphate is districts, ever a choice of
mes exists, the six times more abundant than in others, we have farmer prefers one variety to another, because of a arrived at an intelligible cause of the difference difference, real or fancied, in their effects upon his which different limes present, in the character of land. It was something to ascertain the nature manures. To a soil naturally deficient in phosand cause of these diversities ; to explain, by phates, and in districts where the artificial applicaanalysis, the chemical differences between the tion of phosphates is unknown, the use of one of limes from which such different effects followed ; these limes rather than the other must be attended and thus to connect observation and science. But with important consequences. when practical men are at issue among themselves Not only are such considerations economically —when they cannot agree on the unknown quali- useful to the practical man-in showing him how ties of a new variety of lime—when a prejudice and what to select, and the relative money values exists against all the limes of a given district, in of this or that variety—but they explain why in consequence of the mischief done by the lime of some places land will bear and pay for liming much some particular lime-beds, or lime-works-chem- longer than in others; why some soils remain long istry has rendered the parties a still more obvious fertile without any artificial addition of phosphates ; service. To the manifest advantage of both lime- and how in some localities the rearing and breedburner and farmer, it is able rigidly to fix the ab- ing of stock, and the reaping of yearly corn, may solute and relative values of each variety, and in be continued from generation to generation without every locality.
apparent injury to the land. It is among the interesting consequences, by One example, among the numerous perplexities which all minute researches into nature are at once of the farmer, we may venture to specify, as the rewarded and encouraged, that the pursuit of one statement we have just made bles us to explain object almost invariably leads to the unlooked-for it. Dairy husbandry has long prevailed in Cheshdiscovery of others—as the high road to a great ire. Now it has been ascertained that every milk city leads us past many mansions, opens up beau- cow robs the land annually of as much phosphate tiful prospects, and brings us now and then to of lime as is present in eighty-two pounds of cross-roads where finger-posts indicate the way to bone-dust. From being thus gradually despoiled places of which the very existence was previously of this valuable mineral, the Cheshire pastures unknown to us. The study of limestones, with a have become less rich in nutritious herbage ; and view to economical purposes only, would furnish hence the peculiar benefit derived from boning us with instances in point. We will mention one them—a practice now so extensively and profitof them, chiefly because of its close relation to the ably introduced. But the Cheshire farmers found illustration we have already drawn from the min- that after their land had been limed, bones were, eral phosphates of the greensand and the crag. to a great degree, a failure ; while, conversely,
In noticing these phosphates, we explained how some observed that, after a heavy boning, lime was essential they were for the production of bone in not so immediately remunerative. The analyanimals, and that to all plants they were a necessary sis of the soils and of the limes usually applied of life; that therefore they must exist, to a certain in that county, cleared up both appearances. The extent, in the soil from which plants draw their soil being poor, both in lime and in phosphoric mineral food ; and that they constituted most valu- acid—the two ingredients of bone-earth-was less able manures, accordingly, whenever any deficiency grateful for the after application of lime, because in respect of them had to be supplied.
the bones had already given it a certain dose of Now, in analyzing limestones and burned lime, this substance; and, on the other hand, the soil it has been discovered that a trace of this phosphate was less remarkably affected by bones, because of of lime exists in them all. In some it is merely a the notable quantity of phosphoric acid which lime trace, in others it amounts to a sensible and practi- of a certain quality had previously conveyed to it. cally useful proportion. One of the main benefits The money value to practical men of an accurate knowledge of calcareous substances, is strik- more cautious practitioners warned their brethren ingly illustrated by the fact that a few years ago a by their own experience; which the more complete patent was obtained for the process of burning the and correct deductions of science have since conshell-sand (sea-sand mixed with fragments of shells) firmed and explained. Manures containing nitrowhich occurs so abundantly on the coasts of Corn- gen are available in all soils in promoting luxuwall and of the Western Isles. Plausible state- riance of growth; but the solubility of such ments concerning the value of this burned sand as substances as saltpetre and common salt, is one of a manure were circulated and believed ; and much the very properties on which their immediate and money was wastefully expended in the purchase successful action upon plants depends. It required of it. The publication of an analysis of its con- the successive crops of two harvests, however, to tents by a competent authority at once destroyed convince the parties of their imprudence. the charm, and protected the farmer from further These insoluble manures have now disappeared imposition—at least, in this particular.
from the British markets ; purely mineral mixEven the theoretical views of men of science in tures, however, still retain an uncertain and temregard to fertilizing substances have often a direct porary hold upon public favor. But two facts are bearing upon practice. In England we are fond sure to banish them from the list of fertilizing of novelty ; and we frequently yield our assent to substances, which can generally be relied upon in scientific opinions when given forth with sufficient all soils and for all crops. These are, first, that confidence, and expend our money in obedience to plants do really obtain and require from the soil them. It is far from true that, by despising and certain forms of organic food ; and, secondly, that neglecting science himself, the practical farmer all naturally fertile soils do contain a sensible proescapes from its influence. The speculations of portion of such organic matter. Suppose a soil the men he underrates affect in an important degree to be deficient in this organic matter, a purely minthe profits of his class notwithstanding. Of this eral manure, however compounded, cannot supply we can now give a striking illustration. Analy- it; and the application of such a manure upon such sis in the laboratory of the chemist had ascertained soils must be followed by a failure. But let it be that ammonia exists in the atmosphere to a certain naturally rich in such matter, and the mineral mixextent, and that plants ways contain a uantity ture may possibly be applied with a profit. of mineral matter, derived from the soil. In the It must appear, therefore, how economically mean time experience had. found in the field, that important it is to practical agriculture, that scimineral substances, such as salıpetre, nitrate of ence should be steadily and cautiously prosecuted 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 grow-farmer's pocket is a knowledge of the scientific ing crops. Upon these facts, Liebig ventured principles on which his art eventually rests. boldly to propound two opinions—first, that the Without that knowledge, however much he may application to the soil of substances containing ni- undervalue it, lie is at the mercy of every rash trogen was wholly unnecessary, because the am- hypothesis, and may be induced to expend his monia of the atmosphere was sufficient to supply money upon the nostrums of mere money-seeking all they required of this ingredient ;* and next, quack-salvers. that a proper admixture of mineral substances was Thirdly. The Dairy and the feeding of stock all that a manure need contain in order to render form another general branch of husbandry, to the land fertile for any crop.
Thus mineral ma- which science has been of no less positive use, nures were strenuously recommended-alone, and than to the two departments which, in the prefor all soils. Proceeding upon the assumption ceding pages, have principally engaged our attenthat the rains are continually washing from the tion. Indeed, this must have already struck the soil its mineral constituents in proportion as they reader, from what we have said upon the subject of became dissolved, he next concluded that the ac- food, and from the brief allusion we have made to lion of his mineral mixtures would be more per- the specially exhausting effects of the dairy husmanent and efficient if, by some chemical process, bandry upon the soils of Cheshire, and the mode of they were rendered more sparingly soluble in repairing them which chemistry supplies. water. Hence the origin of the patent manures In the case of dairy farms, the chemical examcalled after his name. They profess to contain all ination of milk drawn from different animals, and the substances which the crops for which they are under very varying circumstances, has provided us intended can require from the soil, and to contain with a body of facts which admit of numerous them in a state in which the rains would not easily profitable applications. Thus it is ascertained remove them.
that the curd and the butter of milk correspond to The love of novelty, assisted by faith in a the muscle and fat of the animal. Hence the readeservedly high name, has caused thousands of son why good milkers are generally poor in conpounds to be spent in the manufacture of these dition, and why the milk falls off when they begin manures, and many more thousands in the pur- to fatten. And as the curd and butter, like muschase of them ; while even larger sums have been cle and fat, are derived immediately from the food lost by the more or less partial failure of the crops which the cow eats, and as we know the respecthey were intended to improve. It was in vain that live sources of these, we can in some measure * The reader is, probably, aware that ammonia consists contain. If it is to be rich in butter, we select a
control the proportion of each which the milk shall of the two gases, nitrogen and hydrogen.
food which, like linseed or linseed cake, is natu- more nutritious in its recent than in its dry state, rally rich in oil, or we mix other cheaper forms and how the loss in drying is to be prevented of fatty matter directly with the ordinary food. If why new corn, wheat, beans or oats, are unwholecurd (or cheese) is our object, we give food, such some food for a horse—why new oats make him as beans and cabbage, which analysis has shown greasy-why kiln-dried oats affect his kidneysto be rich in gluten, or in some other of the so- why hunters keep their condition better on the called protein compounds. And if, while we are common Angus than on the potato oat, and why rearing calves, we wish to sell the milk which is the meal of the former variety is a better support high in price, we can, from our knowledge of the for the Scottish ploughman ;—these are all quescomposition of milk, and of the various kinds of tions which chemistry has taken up, and has sucfood at our command, provide an artificial substi- ceeded in fully solving—or is confident in its abiltute which will serve exactly the same purpose in ity to solve—and the least informed in practical feeding and rearing the calf, and yet cost less matters must see how the solution of every one of money than the sale of the milk brings in. these problems more or less directly affects the
Our limits do not permit us to introduce other pecuniary interests of the holder or possessor of detailed illustrations of the uses of chemistry to land. We might enumerate scores of other questhe dairy. Why butter is hard or soft-how its tions of a similar kind, which only scientific invesquality is to be improved or maintained—how it is tigation can answer; and, as in the preceding part to be best preserved—why it becomes rancid, and of this paper, we might illustrate, by numerous how such a change is to be prevented—what takes examples, the direct money value of such researches. place during the process of churning, what during But our limits compel us to refrain. 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
“ 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 When the principles on which the improvement dairy farmer.
of land is based are once fully understood—when In our climate, the rearing and feeding of stock the elementary substances are known, which are is scarcely second in importance, as a source of necessary to render a soil fertile, or to make a crop rural profit, to the growing of corn ; and there are grow healthily and with luxuriance, and also their many who think that, under our altered fiscal reg- opposites—all we require to learn of any subulations, it must and ought to become the more stance, with the view of determining whether or important of the two. It is certain that, so far as not it will form a useful application to the land, is, climatic conditions go, green crops appear to be what it consists of, and in what state of combinamore natural productions of our rainy islands than tion its constituents exist. We can then procrops of corn. But, for the feeding of animals, nounce with certainty whether it can be of any use science has done at least as much as for the cul- to vegetation, and upon what soils and crops, and ture and fertilizing of the land. The several pur- in what quantities, it is likely to produce the most poses which are promoted by food have been inves- beneficial effects. Chemical analysis, therefore, tigated—what it must be fitted to serve if it is to determines the valu to the farmer of the refuse of keep an animal in a healthy condition—what is the manufacturer, and upon such inquiries it has the composition of each of the more common kinds expended considerable time and minute attention. 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, for tain 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 The economical inquiry is, What is the worth of food will keep an animal in condition for hard or the refuse, calculated at the market price of the fast work, while another makes him heavy, sleek, useful ingredients it contains ? and, further, What or fat—why the same kind of root crops are not is its worth to this or that farmer living at this or always equally nutritive, what power we possess that distance from the manufactory, and having to to increase their natural nutritive quality, or, transport it thither? when this quality is lower than usual, to bring it For instance, the refuse substance, though posup to the natural standard—why green herbage is sessed of a certain money value on the spot where