1UAUS2JMMES
 
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 irmttf, 
 
 KENNINGTON, NEAR LONDON. 
 
 PRINCIPAL: 
 
 J. C. NESBIT, F.G.S, F.C.S. 
 
 CONSULTING AND ANALYTICAL CHEMIST; CORRESPONDING MEMBER OF THE CENTRAL AND NATIONAL 
 
 AGRICULTURAL SOCIETY OP FRANCE; AUTHOR OF "AN ESSAY ON THE MINERAL 
 
 CONSTITUENTS OF THE BOP PLANT j" KTC. 
 
 A LIMITED NUMBER OF STUDENTS are received at the College, at which 
 unusual facilities are afforded of acquiring a thorough knowledge of Analytical 
 Chemistry, and every other branch of scienre requisite to prepare youth for the 
 pursuits of Agriculture, Engineering, Mining, Manufactures and the Arts. 
 
 A few acres of land attached to the premises are appropriated for experi- 
 mental purposes and the recreation of the Students. Gentlemen intending to 
 become Farmers, Land-stewards, Chemical and Manure Manufacturers, or 
 Managers of Mining Property, will find every opportunity for obtaining the 
 information they require. 
 
 Analys.es and Assays of every description are promptly and accurately 
 executed at the College, and Mr. NESBIT may be consulted respecting the pre- 
 paration of artificial manures, and upon all subjects connected with chemical 
 patents and manufactures, and the geological survey and drainage of estates. 
 
 ANALYTICAL AND ASSAY DEPARTMENT. 
 
 FEES FOE ANALYSES. 
 
 FULL ANALYSES. s. d. 
 
 1. Full Analysis of Manure, and determination of each separate 
 
 ingredient, as preliminary to report thereon, from 5 5s. to 10 10 
 
 2. Full Analysis of Soil, Marl, Clay, or other similar sub- 
 
 stance, and determination of each component, from 5 5s. to 10 10 
 
 COMMERCIAL ANALYSES. 
 
 3. Commercial Analysis of Guano, Superphosphate, and other 
 
 similar Manure; including determination of the Phos- 
 phates and Ammonia . . . . .220 
 
 4. Commercial Analysis of Bone-black, or Animal-black, Cal- 
 
 cined Bones, Coprolites, &c., including Phosphates . 110 
 
 5. Determination of Ammonia alone, in Guano, or other similar 
 
 Manure . . . ... . 110 
 
 6. Commercial Analysis of 'certain compound Manures, in- 
 
 cluding determination of Nitrogen, in Nitrates, Organic 
 Matter, Ammonia, &c., with Phosphates and Saline 
 Ingredients . . .330 
 
 7. Analysis of Soil or Marl, generally sufficient for Agricultural 
 
 purposes . . .330 
 
 8. Determination of insoluble Siliceous Matter, Alumina, and 
 
 Iron and Lime in Marl or Soil . . , .110 
 
 The Terms for other descriptions of Analyses and Assays, may be known on application, Sam- 
 ples may be sent by post, in the manner described on page one hundred and five.
 
 RECENTLY PUBLISHED BY LONGMAN AND CO., 
 
 Price i/i a large Sheet for mounting, \. ; in Pamphlet farm, Is. ; in Pamphlet form, u-ith 
 
 Geological Map, 3*. Gil. 
 
 A TAKULAR VIEW 
 
 OF T1IK 
 
 PRINCIPAL FOSSILIFEROUS DEPOSITS 
 
 OK 
 
 THE BRITISH ISLES, 
 
 I'ltEI'AKED ORIGINALLY FOR THE USE OF THE STUDENTS OF THE AGRICULTURAL AND 
 CHEMICAL COLLEGE, KF.NNINOTON. 
 
 BY JOHN MORRIS, F.G.S. 
 
 THE FOLLOWING HIGHLY APPROVED BOOKS, 
 BY MR. A. NESBIT, 
 
 Are Published by LONGMAN $ Co., and may be hid of all Bookellerg. 
 
 \. A complete Treatise on Practical Land Surveying in all its departments, 
 with Railway Engineering and Plane Trigonometry. Ninth Edition, 
 price 12s., in boards. 
 
 2. A Treatise on Practical Mensuration, in all its branches, with Plane Tri- 
 
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 3. A Key to the Practical Mensuration. Eighth Edition, price 5s., bound. 
 
 4. A Treatise on Practical Arithmetic. Part 1st. Fourth Edition, price 
 
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 5. A Treatise on Practical Arithmetic. Part 2nd. Containing the higher 
 
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 2s. 6d., bound.
 
 ON 
 
 AGRICULTURAL CHEMISTRY, 
 
 AND THE 
 
 NATURE AND PROPERTIES OF PERUVIAN GUANO 
 
 J. C. NESB1T, F.G.S., F.C.S., ETC. 
 
 PRINCIPAL OP THE AGRICULTURAL AND CHEMICAL COLLEGE, KENNINGTON ; CORRESPONDING MEMBER 
 
 OP THE CENTRAL AND NATIONAL AGRICULTURAL SOCIETY OP FRANCE; AUTHOR OP "AN ESSAY 
 
 ON THE MINERAL CONSTITUENTS OF THE HOP PLANT;" ETC. 
 
 THIRD EDITION. 
 
 LONDON : 
 LONGMAN AND CO., PATERNOSTER ROW. 
 
 Entered af Stationers' Hall.
 
 OOVOII Mlt'AKK, PI.KKT BTUKKT.
 
 6V 1 
 
 s 
 
 6 
 A/V7 
 
 PREFACE. 
 
 THE following Lectures were delivered at various Farmers' Clubs 
 and Agricultural Meetings, during the last few years. Their 
 object was to render more familiar and popular the science of 
 Agricultural Chemistry, and to divest it as much as possible of 
 dry details and technicalities. Having been often requested to 
 publish some of my lectures, I have selected the four following, 
 which I trust will be found to contain in a condensed form the 
 chief principles of Agricultural Chemistry. 
 
 The article on Peruvian Guano, first printed in 1851, was 
 very favourably received. I have therefore ventured, after care- 
 ful revision, again to present it to public notice. 
 
 The mode of calculating the value of manures is one which 
 I have for many years adopted, and I trust the ease, accuracy, and 
 simplicity of the plan, will make it of considerable utility to the 
 farmer. 
 
 J. C. NESBIT. 
 
 Kennington Chemical and Agricultural College, 
 March 5th, 1856.
 
 CONTENTS. 
 
 i. 
 
 PAG K. 
 
 ON GENERAL AGRICULTURAL CHEMISTRY, AND THE NATURE AND APPLICA- 
 TION OF MANURES . . . . . . . . . . 6 
 
 II. 
 
 THE ADULTERATION OF ARTIFICIAL MANURES, AND THE BEST PRACTICAL 
 
 .MEANS OF DETECTION . . . . . . . . . . 34 
 
 III. 
 
 THE USK AND ABUSE OF LIME IN AGRICULTURE . . . . . . 52 
 
 IV. 
 
 THE QUALITIES OF DIFFERENT KINDS OF FOOD, AND THE BEST METHODS 
 
 OF FATTENING STOCK . . . . . . . . . . 65 
 
 V. 
 
 ON PERUVIAN GUANO : ITS HISTORY, COMPOSITION, FERTILISING QUALITIES, 
 
 AND MODE OF APPLICATION TO THE SOIL . . . . . . 83 
 
 History of Guano, and Sources of its Supply . . . . . . 84 
 
 Mode of Applying Guano to the Soil . . . . . . . . 90 
 
 Mode of Applying Guano to Various Crops . . . . . . 95 
 
 Composition of Guano , . . . . . . . . . . . 103 
 
 On the Adulteration of Guano .. .. ' .. .. .. 106 
 
 Methods of Detecting the Adulteration of Guano . . . . . . 1 08 
 
 Practical Experiments with Guano .. .. .. ..114 
 
 VI. 
 
 DETERMINATION OF THE VALUE OF MANURES . . . . . . 123 
 
 VII. 
 
 ON NITRIFICATION Letter to the late Ph. Pusey, Esq. . . . . . . 127
 
 
 AGRICULTURAL CHEMISTRY. 
 
 ON GENERAL AGRICULTURAL CHEMISTRY, AND THE 
 NATURE AND APPLICATION OF MANURES. 
 
 IN appearing before you for the purpose of offering some remarks 
 on the nature of manures, I do not profess to teach the or- 
 dinary routine of practical farming. I aim only at illustrating 
 your practice by observations and instances ; and, as I conceive 
 that we are all benefited by having some leading idea to connect 
 together as a whole the scattered facts with which we become 
 acquainted in our ordinary intercourse with things around us, 
 so I think it 'possible to convey to you this evening that which 
 will place you in a position to combine many of the facts of 
 which you are cognisant, and which will probably induce you to 
 modify your farming operations, in many cases, with considerable 
 advantage. What I shall endeavour to do, then, is to show " of 
 what manure actually consists, its real sources, and how it may 
 most readily be obtained." It is my intention first to take the 
 most general view of which the subject will admit, and then 
 to gradually enter into details and particulars in which you are all 
 interested. If, therefore, for the first few minutes, you appear to 
 be led away a little from the subject, you will afterwards per- 
 ceive the connection. 
 
 B
 
 i.i ( i i KI -> 
 
 ON AOniCUI.TURAI, ( HKMIsTHY. 
 
 Plants, gentlemen, are tin- main Mihject of our iixjiiiry this 
 evening. The composition and the- habits ol' a plant must 1..- 
 ascertained before we can know what manure.- are adapted fur it. 
 Now if you examine the structure of ordinary land-plant-, 
 will find that they an- provided with roots which arc sent down 
 into tin- soil, and that these roots not merch si rve the purpose of 
 retaining the plants in the soil, hut are full of minute vessels which 
 have the power of absorbing from the soil materials rendered 
 soluble by water, and of taking them up into the plant and t! 
 into the leaves. The leaves are spread abroad to the air, and when 
 the sip which rises from the roots of the plant finds its way into 
 the leaves, they have the power, during certain seasons, of>.ictiim 
 upon this juice, and preparing the materials upon which the plant 
 grows. In other words for on this point I wish to be very explicit 
 the roots run down into the soil, and absorb certain material.- 
 which exist there ; the leaves are sent into the air, and absorb 
 certain materials with which it abounds, and during sunlight or 
 diffused daylight, when there is a certain amount of light and heat 
 in the atmosphere, that is, in summer or spring weather, they 
 have the power of uniting these materials and forming the various 
 substances which constitute the fabric of vegetables. Now we 
 thus learn that the roots of land-plants serve other purposes 
 than merely to retain the plants in the soil. The roots of sea- 
 plants, on the contrary, only serve as means of attachment to the 
 rocks. The leaves of sea-plants perform the functions both of the 
 roots and the leaves of land-plants ; because, being constantly in 
 contact with the water, they absorb the saline matters from the 
 sea-water, as land-plants absorb the same from the soil by their 
 roots, and they also act on organic elements by means of the light 
 of the sun upon the leaves. The substances which are ordinarily 
 taken up by the roots of plants, and those which are taken in by 
 the leaves, are very different. If you take any vegetable, say 
 wheat, or wheat-straw, or hay, or any other material of that kind, 
 and burn it, you send back into the air the materials which the 
 plant originally derived from the air, and there remain behind, in 
 the form of ash, the materials which the plant by its roots d.
 
 NATURE AND APPLICATION OF MANURES. 7 
 
 from the soil. So that we have a general division of the con- 
 stituents of any vegetable body into two varieties, namely, those 
 materials derived from the air, and which may be called atmo- 
 spheric or organic elements, and those derived from the earth, 
 and which may be called mineral or earthy elements. The terms 
 "mineral" and "organic 1 ' may be thus explained: If a plant 
 be burnt, the ashes represent the mineral matter taken from the 
 soil ; while the part consumed is the organic matter taken from 
 the air. 
 
 It must be apparent to you, from what I have stated, that 
 the whole manuring principle which a plant in its wild state 
 can possibly obtain, must come from the earth and the air. If we 
 look around us, we find that nature is everywhere quite capable 
 of furnishing to wild plants all that they require. Rocks, which 
 do not contain the slightest amount of any material that is ob- 
 tained from the air, but only mineral matter, after they have been 
 exposed to the air for a while, are found to be covered with 
 vegetables of one kind or another. What is the common action 
 of nature upon a bare rock which is protruded in any way ? You 
 first have some lichens (a kind of mushroom) growing over the 
 surface of the rock. These plants have the power, without the aid 
 of anything from the soil except mineral ingredients, of attracting 
 other substances from the air. After generations of these have 
 grown and died, mosses take their place, and grow upon the 
 remains of a kind of mould which has been made by the decay of 
 the lichens. After the moss has grown for some years, you will find 
 different kinds of natural grasses. These are succeeded by others, 
 until at last you have, upon what was originally bare rock, a soil 
 formed naturally, in which trees can and do grow from seeds natu- 
 rally sown in it. Take, for example, the lavas ejected from Vesuvius, 
 ^Etna, and other volcanoes. These lavas, which have been molten 
 and red hot, of course contain no vegetable matter. They have 
 not been long cooled before the wild fig-tree and other plants, 
 sending their rootlets into the interstices, spring up and produce 
 abundance of woody matter, which must evidently have been 
 obtained from the air, as it did not exist in the soil. Take
 
 M (TURKS ON Af. KH fl.TURAI. CHEMISTRY. 
 
 another case, that of a wild waste, such as \\e find in many parts 
 of Scotland, where pines and other trees have since grown up 
 in a soil which contained at first little or no vegetable- matter. 
 These trees have grown for a long period. In the course, perhaps, 
 of thirty or forty years, they are cut down, and hundreds of loads 
 of timber are taken away from every acre on which they were 
 planted ; yet the soil is richer in vegetable matter now than it was be- 
 fore the trees were put there. It is clear, then, that there is some- 
 thing in the air which these plants have the power of obtaining ; 
 and it is this which enables nature to clothe the surface of 
 different rocks with plants of various kinds, so as to present, 
 even when man does not come on the stage at all, a fine scene of 
 foliage wherever moisture and water and other elements of vegeta- 
 tion can be found. 
 
 If it be the fact, gentlemen, that plants obtain a great portion 
 of their nutriment from the air, you will see that the consideration 
 of what is obtained from the air and what from the soil is very im- 
 portant indeed to all persons who are engaged in practical farming. 
 Now, if we examine the materials that are driven off by a red 
 heat from any plant whatever, we find them to consist chiefly of 
 four. One is carbon or charcoal. This is a most important ele- 
 ment, and is obtained from the air. Whenever charcoal is burnt in 
 an open fire, you have a certain portion of the air called oxygen 
 uniting with the charcoal, and converting it into what is called car- 
 bonic acid gas. I would remind you that carbonic acid gas is given 
 out from fermenting vats, and from the burning of all bodies con- 
 taining charcoal ; and that, speaking generally, whenever any veget- 
 able or animal body is decaying, this gas is evolved and sent into 
 the air. Air contains about two parts of carbonic acid gas in ten 
 thousand. Another of the bodies which plants derive from the air 
 that is, from the water which comes down from the air is 
 hydrogen. This is found in all common coal gas. It is also present 
 in water ; nine tons of water containing one ton of this substance. 
 Plants have the power of separating the hydrogen and of retaining 
 it, giving off oxygen into the air. Then we have another body 
 called nitrogen. Nitrogen is the basis of all animal muscle, and
 
 NATURE AND APPLICATION OF MANURES. 9 
 
 is found in large quantities in all the seeds of plants, because 
 they are destined to feed animals, which require its presence to a 
 large extent. It is derived by plants from certain of its combi- 
 nations contained in the air. Then you have the body called oxygen, 
 which is the vital principle of the atmosphere ; which constitutes 
 eight parts out of nine, by weight, of water ; and which is abun- 
 dantly supplied to plants both by water and by the air. I mention 
 these bodies merely that they may be known ; I shall not allude 
 too fully to their chemical re-actions, because I wish to keep 
 as free as possible from technical phraseology. Well, now, what is 
 the effect of the leaves of plants upon the air, when they are acted 
 upon by the light of the sun ? Plants have the power of deriving 
 carbonic acid from the air by means of their leaves, and of 
 retaining the carbon and sending back the oxygen. They have 
 the power of taking the water in the same way, and when 
 acted upon by the light of the sun, of retaining the hydrogen 
 and sending back the oxygen. They have the power also of 
 acting upon a component of the atmosphere called ammonia , 
 which contains nitrogen, and of retaining the nitrogen and also 
 the hydrogen. This power they exert continually during the 
 full bright light of the sun, and more slowly in the diffused 
 light of day. If any of you wish to try the experiment, get a 
 bottle of soda-water, which contains carbonic acid gas ; pour some 
 of it out, then fill the bottle with common water, and invert it in 
 a basin of water ; then take a few sprigs of fresh mint, introduce 
 them under the water into the bottle, and expose that to the light of 
 the sun, and you will find a very active operation going on ; small 
 globules of gas being given off by the leaves of the mint. Now 
 oxygen is a gas very easily detected, because anything burns in it 
 much easier than in common air, and if you examine the liberated gas, 
 and put into it a bit of paper just red-hot at the end, you will find it 
 blazing in a moment ; showing that the carbonic acid gas in the soda- 
 water is decomposed by the leaves of the mint under the action 
 of the sun, the carbon being retained while the oxygen is given off. 
 Another instance of this powerful action under the influence of 
 sunlight is furnished by an experiment tried by a French phi-
 
 10 ' LECTURES ON AGRICULTU H A I. < 1IKMISTUY. 
 
 losopher. Many of you must be aware that carbonic acid gas, 
 when sent through limr-water, produces a white precipitate. The 
 French philosopher took a long glass tube and inserted in it the 
 branch of a living vine. He closed up one end of the tube, all 
 but a single aperture, through which he sent a current of air mixed 
 with a certain portion of carbonic acid. The other end he also 
 closed, except one tube, which was passed into lime-water. As 
 the carbonic acid would immediately produce a precipitate in lime- 
 water, he could at once tell whether the light of the sun, shin 
 upon the branch in the tube, produced any effect upon the carbonic 
 acid passing through. He first covered the tube to keep out the 
 light, and passed the gas through the tube into lime-water, in which 
 it gave a dense white precipitate. He then removed the jar of lime- 
 water, took the cover off the tube, and let in the light of the sun. 
 He sent a current of gas through the lime-water again, but not the 
 slightest trace was there of carbonic acid : every particle of it had 
 been absorbed and retained by the leaves of the plant for its own 
 use. The leaves had retained the carbon and given out the oxygen. 
 You would hardly suppose that there existed in the air a sufficient 
 quantity of carbonic acid to supply the great wants of vegetation; 
 but if we bear in mind that the atmosphere is forty miles high, 
 that it contains two parts in ten thousand of this gas, and that its 
 weight is fifteen pounds upon every square inch of the surface of 
 the earth, we shall perceive that the quantity is a great many times 
 more than all the carbon that exists in all the vegetation of the 
 earth, and more, probably, than exists in all the known coalfields 
 as well. The fact is, that the quantity of carbon existing in the air 
 would be more than sufficient for a vegetation ten-fold that of the 
 present. In consequence, also, of the continual decay of vegetable 
 and animal matter, and of the whole of the carbon being returned 
 to the air, there never can be any want of carbon for the use of 
 plants. 
 
 From the water which falls from the air plants obtain their 
 hydrogen, while they have, at the same time, the power of retain- 
 ing it, and giving back the oxygen. They have likewise the power 
 of acting upon the ammonia, retaining the nitrogen, together with
 
 NATURE AND APPLICATION OF MANURES. 11 
 
 the hydrogen if they require it. Plants also possess the power of 
 decomposing nitrates, and of retaining the nitrogen. From the soil 
 they likewise obtain the mineral ingredients which they require ; 
 for instance, phosphate of lime. We all know that bones con- 
 tain a large amount of bone-earth, or, as chemists call it, phos- 
 phate of lime. Animals feed upon vegetables, and if the vegetables 
 they consume did not contain phosphate of lime, they could not 
 exist. All vegetables, therefore, or those portions of them which 
 are adapted for animal life, contain phosphate of lime ; they also 
 contain certain portions of silica or sand in a soluble state, soda 
 and potash, lime and magnesia, common salt, oil of vitrol or sul- 
 phuric acid, in the form of sulphate of lime or some other sulphate. 
 These the plants derive from the soil. What, therefore, constitutes 
 manure for the plant is what the plant derives from the soil and 
 the air ; that is to say, every substance which is required to make 
 up a plant is adapted for manure. You will see, then, from what 
 I have stated, that the real sources of all manure are the air and 
 the earth. No matter what the manure is, or where it comes from, 
 you can trace it back to these sources the air on the one hand, 
 and the earth on the other. 
 
 Let me here point out to you one or two facts of considerable 
 importance. The first is, that plants in their ordinary natural 
 state, as they are found upon different soils, are adapted to take 
 what they want from the air ; yet when you come to work in an 
 artificial manner, which farmers do, this cannot be relied upon. If 
 you were to leave your fields to themselves, you know what would 
 be the result : nature would fill them with plants. But you do 
 not want those plants which nature would put there ; you want to 
 grow certain kinds of plants which will yield a profit in the 
 market, but which are not natural or indigenous to the soil, or 
 which would not naturally grow in remunerative quantities ; and 
 therefore you will, under these circumstances, have to act 
 somewhat differently from nature, or rather, you will have to 
 assist nature, and make her work for you. One of the great 
 powers which soils possess is that of absorbing from the air 
 certain gaseous materials, the very same substances which plants
 
 1'J LECTURES ON AI . i: 1 1 ' l.TUKA I, CHKMISTHY. 
 
 absorb. Let me for a moment allude to ploughing, or rather to 
 fallowing. What do you do when you fallow the land ? Do you 
 not expose the land by repeated turnings to the action of tin ,-iir f . 
 Do you not allow it, if it have any absorbing powers, to al<>rl> 
 what it can from the air? Do you not suffer it to lie in a porous 
 state, and afford it all proper opportunities of acting upon the 
 air ? The consequence is, that by fallowing, you cause the porous 
 body, the soil, to act upon the air ; and there is absorbed a con- 
 siderable portion of ammonia, nitric acid, carbonic acid, and other 
 materials essential for the growth of plants. You afterwards take 
 a crop ; and is it surprising that you find fallowing beneficial when 
 you have exposed the land for twelve months, without a crop, to 
 the action of the air ? You not only secure what the plants can 
 take from the air by their leaves, but have them taking up by 
 their roots from the soil that which the soil has, during twelve 
 months, been taking from the atmosphere. This is the natural 
 system of manuring; and there can be little doubt that, under 
 certain circumstances, it is beneficially practised by the farmer. 
 The process of fallowing is neither more nor less than one of 
 those practical plans by which you place in the soil an additional 
 quantity of the materials which are required for an increased growth 
 of vegetables. It is, in fact, a system of manuring from the air. 
 
 Now let me here point out, that without draining it is perfectly 
 absurd to think either of fallowing or of ploughing. What is the 
 use of draining ? If a soil act by means of porosity upon the air, 
 as I have told you it does, of course when its pores are filled with 
 water no such action can take place. Therefore, it is a sine qua 
 non for all farmers, that the soil shall either be naturally sufficiently 
 porous for the water to descend, and the air to enter ; or, that it 
 shall be brought into that state artificially that is, by proper 
 draining. Whatever I may have to say, therefore, with respect to 
 the application of manures in general has no reference whatever 
 to undrained land, but applies to land which is in such a state of 
 porosity that air and water can enter, so as to have their decided, 
 proper action upon the soil. 
 
 Allow me to introduce incidentally another point, which I shall
 
 NATURE AND APPLICATION OF MAXUJiES. 13 
 
 dwell upon further when I come to speak of manures, I do not 
 know whether you are aware of the composition of the atmosphere. 
 The atmosphere is a great source of one of the forms of manure. 
 Nitrogen exists in the form of ammonia, as, for example, in ladies' 
 smelling bottles, and as you detect it in your stables; it is also found 
 in the form of nitric acid, as in nitrate of soda. Now, not only do 
 soils absorb ammonia, and also nitric acid, from the air in the manner 
 that I have described, but the air itself, by means of rain, gives every 
 year, to an acre of soil, a quantity of ammonia* and nitric acid which 
 would astonish you. It has been proved by some very recent ex- 
 periments (not yet, I believe, noticed in this country), made by a 
 learned French chemist,* that the rain-water which descends in the 
 neighbourhood of Paris contains a quantity of nitric acid arid 
 ammonia which I have estimated to be equal to a dressing of two 
 hundred weight of Peruvian guano per acre. If your land, there- 
 fore, is not drained, but is plugged up with water to the surface, 
 the splendid manures which descend in the rain to the extent of 
 which I have spoken will run off on the surface ; and, not entering 
 the ground, will not yield more than one-third or one-fourth of 
 their proper manuring value in your crops. 
 
 Let me further observe, that there ought to be calcareous 
 matter in all your soils. There is plenty of it in many dis- 
 tricts, in the form of chalk, marl, limestone, &c. ; and in warm 
 weather there is a process of absorption of ammonia in the 
 air going on naturally in these soils ; the ammonia, as it is 
 absorbed, being converted into nitric acid. We are all apt to 
 look upon saltpetre rather as a means of blowing people's heads 
 and bodies asunder than under any other aspect ; but we must not 
 forget that it is in fact one of the main articles of the farmer's pro- 
 duction. In the wars of our Revolution, in the time of Cromwell 
 and Charles I., all the saltpetre with which the combatants blew 
 one another to pieces was made from the mortar of old walls, the 
 bottoms of old stables, cow-houses, and other places where urine 
 had been deposited ; and when we were at war with France, in 
 
 * M. Barrall, Comptc Rendu, vol. xxxiv. p. 824.
 
 14 J.F.CTTTRF.S ON AfiRTrr r.TURAI. CHEMISTRY. 
 
 1798, and had cut off its supply of saltpetre from the East 
 Indies, all the saltpetre used by Napoleon was made from similar 
 sources from the mortar or calcareous matter of old houses, from 
 urine, from animal and vegetable matter collected from various 
 sources, from the bottoms of cow-houses, stables, and other places 
 where urine had penetrated. These, when properly mixed to- 
 gether, produced nitre. The way in which saltpetre heaps were 
 made may be very briefly described. A layer of calcareous mat- 
 ter was put on the. ground, being, perhaps, twenty or thirty 
 feet long, twelve feet wide, and a foot deep ; on that layer were 
 placed horse manure, straw, animal matter, such as horse-flesh or 
 any similar material, then another layer of calcareous matter, such 
 as marl, and old stable stuff, then a layer of manure, and so on 
 alternately. This heap was kept under cover, so as not to allow too 
 large a quantity of water to fall upon it. It was kept moist by being 
 watered with urine, or urine and water ; when urine could not be 
 procured water alone was used. Every three or four months the 
 heap was turned over, being still occasionally watered with urine or 
 water for nine or ten months. After that time it was moistened 
 with water alone ; no more urine was added, and no more vegetable 
 or animal matter. In this manner, in fifteen or eighteen months 
 the whole of the nitrogen and ammonia had united with oxy^yn, 
 and had become converted into nitric acid. This acid, in com- 
 bination with the calcareous- matter, constituted nitrate of lime, 
 nitrate of magnesia, and so on. The heap was then put into a 
 large tank, and well washed with water, which dissolved the nitrates. 
 The liquor pumped away from the residue was boiled with wood- 
 ashes, and this converted it into the nitrate of potash the substance 
 required. It is not necessary for the farmer to use wood-ashes, 
 because nitrates are all equally valuable to him. Such is the mode 
 by which all the saltpetre was made during our own Revolution, 
 and during the first French Revolution. 
 
 I wish now to point out to you, that all soils whatever, con- 
 taining calcareous matter, which are porous and well-worked, and 
 which have derived vegetable or animal matter from the farm, or 
 from any other source, are, more particularly in warm weather,
 
 NATURE AKD APPLICATION OF MANUKES. 15 
 
 always acting as nitre-beds : a fact which has not been dwelt upon 
 as much as it ought to have been with reference to the farming of 
 this country. Wherever there is calcareous matter in the soil, 
 wherever the soil is sufficiently porous and duly exposed to the air, 
 there you not only have the material contained in the soil acting, 
 the ammonia oxydising and giving rise to nitric acid, but you have 
 a continual absorption of this material from the air. All artificial 
 nitre-beds give rise to more nitre than the nitrogen in the ammo- 
 niacal and other substances put into them ought to occasion ; proving 
 that there must be absorption from the air. 
 
 This leads me to notice the experiments of the Rev. Mr. Smith, 
 of Lois Weedon, Northamptonshire. That gentleman has been 
 growing wheat upon the same field year after year without the 
 slightest addition of manure ; he has, in fact, been carrying out 
 Jethro TulPs plan. Jethro Tull had a notion that by pulverising the 
 soil to a very great extent, he could make it sufficiently fine to pass 
 through the pores of the roots and enter the plants, and that thus 
 he could effectually provide against the want of manure. Now, 
 although he had got hold of a bad theory, his practice was to a 
 great extent sound; as was proved by his producing wheat in 
 this way year after year for a considerable period. His plan, how- 
 ever, 'Went out of use, and has not been followed for many years. 
 Within the last four or five years, the Rev. Mr. Smith, who has a 
 few acres of land which is tolerably stiff, moderately absorbent, and 
 well provided with mineral ingredients, has been trying experi- 
 ments of a similar nature. Has he succeeded, you will ask, in 
 producing a crop without manure ? He has not without manure 
 in the sense in which I use the word, but without manure in the 
 sense in which you are accustomed to use it. He has not applied 
 cart-loads of dung to his land, but he has made use of methods by 
 which he has been enabled to obtain manure in a form in which you 
 do not generally recognise it ; and this is one of the great points I 
 have to bring before you, that you may fully recognise the fact 
 that there are other sources of manure besides cart-loads of dung, 
 straw, or guano. After having well prepared the whole field by 
 thorough digging and forking, Mr. Smith dibbles his wheat in
 
 16 LECTURES OX AGRICULTURAL CHEMISTRY. 
 
 rows of three together, each one foot apart, and with a distance of 
 three feet between every three rows of wheat. When the wheat is 
 up, the one-foot intervals between' it are repeatedly dug or turned 
 by a fork about six inches wide, so as not to come nearer the 
 wheat than three inches. Weeds are thus eradicated, and air ad- 
 mitted to the roots. The three-feet intervals are treated through- 
 out the spring and summer as fallows, and are thoroughly turned 
 over in every direction, and well exposed to the air. This is done 
 up to the time when the wheat almost meets over the three-feet 
 spaces. When the crop is ripe it is cut; and the three-feet 
 falloioed intervals are now dibbled with wheat, while the part 
 which bore the wheat is to be fallow. During the last four or five 
 years, Mr. Smith has taken, on an average, from thirty to forty 
 bushels per acre from his land without any addition of manure 
 in the shape of guano or dung, or any other visible matter. 
 He has, however, been manuring all the time ; because, through 
 the constant stirring, there has been a powerful absorption of ma- 
 terials from the air; nitre-beds have been formed, and the result 
 produced is the same that would follow from an absolute dress- 
 ing of nitrate of soda. In cases where the soil has been light, 
 and where the absorbent power has not existed so powerfully, 
 he has used manure, with, I believe, very fair success. He 
 shows a profit of 4 or 5 an acre on his wheat every year. 
 He every year publishes a fresh statement of what he has 
 been doing, and he says that even at the low price of 40.?. per 
 quarter, he realises a profit of several pounds per acre. On lighter 
 soils, as I have said, he is obliged to employ visible manures. It 
 is clear that soils must differ in their powers of absorption. The 
 loamy clays, for instance, have a greater power of absorption than 
 lighter soils, and also contain more available mineral matters. 
 With light soils manures are necessary. I have mentioned this 
 case to you, because I want you, gentlemen, to tell your neigh- 
 bours that manure comes from the air on the one side and the 
 earth on the other, and that a proper working of the land, and a 
 proper exposure of it to the air, will often be as effectual as an 
 actual dressing of visible manure, because the invisible active in-
 
 NATURE AXD APPLICATION OF MANURES. 17 
 
 gradients of the air are absorbed by the soil to be made use of by 
 the plant. 
 
 In the farmer's practice of the rotation of crops, you will find 
 this principle distinctly acknowledged. The rotation, according to 
 the Norfolk system, is turnips, barley, seeds, and wheat. Why 
 is it that this rotation succeeds so well ? You would naturally 
 say that, other things being equal, plants with large leaves would 
 draw more from the air than plants with narrow leaves and small 
 foliage. When the turnip is put into the ground it sends out large 
 broad leaves ; and when a nice breeze passes over them, and the 
 sun shines upon them, there is a very great absorption of materials 
 from the air, which the turnip eventually puts into the bulb for the 
 purpose of producing turnip-seed. That is the simple purpose of 
 the turnip. "But," the farmer says, " I don't want turnip-seed; I 
 want, a little mutton and some barley." If he did not want mutton, 
 he would plough up all the turnips, and put them into the ground 
 to grow his barley. This material, collected in the bulb for the 
 production of seed, is partly consumed by sheep, and the rest is 
 voided by them on the land. The barley is then sown. It has 
 narrow leaves, and it could not absorb more from the air than 
 would produce, perhaps, two or three quarters of barley per acre ; 
 but by the use of the turnip previously, which is better than 
 fallowing, because you have a vital agency in addition, a large 
 amount of nutriment is placed in the ground, which the barley 
 lays hold of, and there is a great increase of crop in consequence. 
 After barley, as preparatory to wheat, you take a plant with 
 large foliage, red clover, or some other clover, which is mixed 
 with grass-seed. Now what does the clover do ? Every little 
 leaflet which it shoots up into the air sends a rootlet downwards; 
 so that in proportion to the upward growth of the clover is the 
 downward growth of the root, and when you have taken the 
 clover away you retain in the shape of roots several tons per acre 
 of valuable vegetable matter, which, by its slow decomposition, 
 affords nutriment for the narrow-leafed wheat. So that by em- 
 ploying, in the first instance, turnipsjbr the barley, and clover for 
 the wheat, you accumulate in the soil a large quantity of ma-
 
 18 LECTURES ON AGRICULTUKAL CHEMISTRY. 
 
 terial absorbed from the air, for the benefit of the after-crops. 
 This may be clearly seen if you consider the difference between 
 cutting clover and feeding it off. It is generally believed that a 
 man who feeds his clover off, with a little oilcake, etc., will get u 
 better crop than one who takes the hay. I know I am here tread- 
 ing on tender ground, but, at the risk of being accused of heresy, 
 I will aver, that the man who spends his money on oilcake, feeding 
 it off upon clover, is committing an error, unless he can realise 
 benefit in the shape of mutton. If you cut clover at midsummer, 
 and let it grow again, and then take another cutting in the autumn, 
 you will afterwards obtain a far better crop of wheat than you 
 would secure by feeding with oilcake, unless you chose to go 
 to an enormous expense. Every leaflet upwards has a rootlet 
 downwards, and if the leaflet be taken off, the rootlet will not 
 grow ; so that if the sheep be fed upon the surface, the under pro- 
 duction is diminished. In exact proportion to the increase of the 
 upper is the increase of the lower ; and if you are always feeding 
 off the former with sheep, you will have but few roots below, and 
 the small amount of nutriment you give in the shape of oilcake 
 will produce little or no effect. A friend of mine tried this in 
 Northamptonshire. He had a field of clover, which he divided 
 into two parts. The whole was cut at midsummer, half was left to 
 grow again, and the other fed off. In October, he staked out two 
 pieces as regularly as possible, and had all the roots dug up, and 
 carefully cleaned and weighed. The result was, that where the 
 clover had been cut once and eaten once, there were twenty-five 
 hundred weight of roots per acre, and where it had been cut twice, 
 there were seventy-five hundred weight per acre ; being a difference 
 of two tons of roots per acre. Who will say, then, that two tons 
 of vegetable matter, containing so much nitrogen as these roots do, 
 were not an exceedingly good dressing ? Of course, the result in 
 the wheat crops was perceptible at once ; and you may depend 
 upon it, that, with one exception, namely, where soils are so 
 light that the mechanical treading of the feet of sheep is a matter 
 of prime necessity, you will always get a better crop of wheat 
 after two cuts of clover than by feeding off.
 
 NATURE AND APPLICATION OF MANURES. 19 
 
 There is one point which I must mention with respect to 
 turnips; because, in order to get a clear notion of manuring, you 
 must attend to many minutiae. Some farmers have a notion I 
 have found it general that sheep and other animals have the power 
 of imparting something to vegetable food, so as to convert it into 
 manure. This is a great mistake. Whether the vegetable food 
 passes through the body of the animal, or goes at once into the 
 soil, if you can ensure a regular decomposition, the effect will be 
 the same. Take the case of a crop of turnips. Suppose you have 
 two pieces of land, each producing twenty tons per acre, and in 
 the one instance you chop up the turnips and spread them on the 
 land, and in the other feed off with sheep and then plough the 
 whole and sow it with barley. I maintain that you would have a 
 much larger crop of barley where you did not feed the sheep than 
 where you did ; that where the turnips were, by themselves, cut 
 up and ploughed into the land, you would have much more nutri- 
 ment adapted for the succeeding plant than where you fed the 
 sheep upon it ; because, while you feed the sheep, it wants some- 
 thing to supply the natural waste of the body, and to increase its 
 bulk, and, after these are supplied by the turnips, the sheep leave 
 on the soil a smaller quantity of vegetable matter to serve as 
 manure than was contained in that upon which they originally fed. 
 Whence can a sheep derive manure except from its food ? It has 
 no power of deriving it from any other source, because the animal 
 is only a consumer it does not impart anything. Therefore, 
 feeding is only a waste, unless you realise a benefit in regard to 
 your stock, which I am happy to find you are all doing. I have 
 known the time when turnips were so abundant that there was not 
 stock enough to feed them off; and when they were ploughed into 
 the land, it produced better crops of barley in consequence. I 
 applied to a number of my friends to try some experiments of this 
 kind, and I have one or two letters here respecting the results, 
 which, with your permission, I will read to you. 
 
 "Old Broad Street, August 10, 1849. 
 
 " In reply to your letter, I am instructed to say that the mem- 
 bers of the Farmers' Moon Club, in the neighbourhood of Rochester,
 
 20 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 Kent, unanimously agree, that vegetable manures are peculiarly 
 fructifying, and that, taking the case of a fallow or other field, 
 being all previously of the some tilth, and sown with rape for feed- 
 ing, and divided into three divisions, one of which shall be fed off 
 with sheep without any extra food to the rape, the second division 
 ploughed in, and the third division fed off with oilcake or corn ; 
 . that the worst corn succeeding the rape, will be on the first 
 division, the next best on the second, and the best on the third. 
 Thus all speak in favour of green crop for manure. 
 
 "JOHN OAKLEY. 
 "J. C. Nesbit, Es^." 
 
 " Naseby, May 15, 1849. 
 
 "I regret I was not at home to answer your inquiry sooner, 
 having been in Yorkshire the last fortnight ; however, I hasten to 
 send you the required information. In the spring of 1846 I 
 had more turnips than my stock could consume ; I thought 
 that it was reasonable that, if the crop was broken to pieces and 
 ploughed in, the grain crop that followed would derive as much 
 benefit as if eaten by sheep. I therefore did so with one acre, in 
 the first week in February, and with another upon the fourth week 
 in March. Part of the rest of the field was eaten on the land, 
 and part being newly ploughed-up land, the whole crop was drawn 
 off. On the land where the turnips (white rounds) were broken 
 and ploughed in on the last week in February, the produce was 
 eighty-four bushels per acre of Hopetoun oats. Where the turnips 
 were broken and ploughed in on the fourth week in March, the 
 produce was seventy-four and a half bushels per acre. Where 
 eaten on the land by sheep, seventy and a quarter bushels per acre ; 
 and on the newly ploughed-up land, the whole of the crop drawn 
 off, forty-one bushels of wheat. 
 
 "PETER LOVE. 
 
 " J. C. Nesbit." 
 
 "Assingtou Moors, June Id, 1849. 
 
 " I have just seen Mr. Underwood, who was a neighbour of 
 mine eighteen years ago, but is removed to a distance. He s.-ivs 
 he has practised ploughing in a few acres of turnips almost every
 
 NATURE AND APPLICATION OF MANURES. 21 
 
 year for upwards of twenty years, and considers three sacks of 
 barley per acre quite within bounds, as the increase from plough- 
 ing in over feeding off. The clover is much better ; but he has 
 not observed the wheat sufficiently to say what the difference is. 
 He estimates an average acre of white turnips to be worth thirty 
 shillings more to chop and plough in, any time before they begin 
 to run to seed (say February out), than to feed off. I inspected a 
 field of wheat this week, belonging to John Gurdon, Esq., which 
 was white turnips three years back ; a part was ploughed in, and 
 the rest fed off with sheep, half a pound of oilcake per day be- 
 ing given to each of them. The wheat, where the turnips were 
 ploughed in, is decidedly b'etter than the rest I think three 
 bushels per acre. Mr. Hudson, the steward, told me the barley 
 was quite a foot higher than the rest of the field, and three sacks, 
 if not more, per acre better. The clover was all fed off, and no 
 notice taken ; nor .would anything more been thought about it, had 
 not the wheat looked so much better than the rest all the spring. 
 The turnips were about three quarters of a plant, but regular ; the 
 sheep went down with the epidemic, and were sold, leaving about 
 two acres of turnips to feed; and rather than purchase any more 
 stock they were ploughed in. As I told you at the club, I am 
 generally a buyer of turnips ; but the obstinacy of my neighbour, 
 Mr. Underwood, who refused to take twenty shillings per acre for 
 his, to feed off (for the sake of convenience to me) when almost 
 everybody else was giving theirs away, attracted my attention to 
 the after crop ; and I can, in two instances, confirm his statements. 
 Notwithstanding, if one and a half hundred weight of Swedes (I 
 think a ton of Swede turnips will make fourteen pounds of mutton, 
 from experiments I have tried), or two hundred weight of white 
 turnips will make one pound of mutton, and we can grow 
 twenty-one tons of the former, and twenty-six or twenty-eight of 
 the latter, it must be more profitable to feed atfivepence per pound 
 for the mutton, than to plough in to gain thirty shillings or forty 
 shillings per acre in the corn crop. I have been unwell, and could 
 not see the parties, or I should have answered your note before. 
 
 "THOS. HAWKINS. 
 
 " Mr. J. C. Nesbit." 
 
 D
 
 22 LRCTURIR ON AOIU(MT I.TURAT. CHEMISTRY. 
 
 There is one part of the first letter in which I do not quite 
 concur. It is the decided opinion of the fanners, in most districts 
 where the experiment has been properly tried, that turnips or rape 
 must be far better for the next crop when ploughed into the land 
 than when fed off with sheep, even with the addition of oilcake. 
 
 This brings us at once to green crops. Supposing you 
 had a farm of a thousand or more acres, and could not stock 
 it at once, one of the best means of increasing the fertility of 
 the land would be to grow rape, or some similar crop, and plough 
 it in, because rape derives from the atmosphere a very large amount 
 of the volatile materials contained in it, and thus for the next crop 
 you would have in the land an aburtdant supply of manure. It 
 is thus that wheat is grown in some parts of America. It is the 
 plan of the growers there to sow clover and plough it in ; then 
 comes a wheat crop ; and after the wheat they fallow for a year, to 
 clear from weeds, and then put in clover again. _ They take wheat 
 in this way every three years, and follow no other mode. They use 
 clover simply for the purpose of obtaining nutriment from the air. 
 
 We now come to the preparation of farm- yard manure. This 
 is generally formed of all the vegetable matters lying about 
 the farm, together with the dung deposited by stock. Now, 
 whether vegetable matter be disintegrated by spontaneous decom- 
 position, or by passing through animals, the result is the same. 
 If I pass a certain quantity of food through the body of an 
 animal, which is continually absorbing air into its system, that 
 air is constantly acting upon the food, and consuming some of 
 it, so that what the animal gives out afterwards is of less value 
 than what it received. If a quantity of straw be trodden down 
 by animals, and thus rotted away, there ensues the same action 
 that proceeds inside the animal, that is, the air acts upon the 
 stra\\, burning a portion of it, and giving out into the air carbonic 
 acid, ammonia, and water, from the decomposition of the vegetable 
 matter ; so that whether you pass the food through the body of 
 the animal, or decompose it in the open air, the ultimate result is 
 the same. There is always something passing into the air for the 
 general supply of nature's fields; the rest remains in the shape of
 
 NATURE AND APPLICATION OF MANURES. 23 
 
 manure. That which passes through the animal is richer than the 
 ordinary farm-yard dung, because of the greater richness of the 
 food it has consumed. If you feed an animal on straw alone, its 
 excrements will be no richer, as regards manure, than straw de- 
 composed in the open air ; but when you feed upon seed, which 
 contains four or five times more nitrogen a substance capable of 
 producing ammonia than straw, and which also contains far more 
 phosphates, the excrements are more valuable than decomposed 
 straw. In no other sense are the results different. If you took a 
 quantity of wheat or linseed, and allowed it to rot, instead of feed- 
 ing animals with it, the residue would be as valuable as the dung 
 expelled from the animal. Therefore, while you use valuable food, 
 because you gain by the conversion of it into beef or mutton, that 
 which is excreted or given out is only valuable because you use a 
 valuable material to produce it. Manure from animal matter re- 
 sembles manure from vegetable matter. We are, in fact, like 
 so many steam-engines ; we are obliged to have our air and our 
 fuel or food to maintain our operations ; and that which is uncon- 
 sumed is cast out, like so many ashes in our grates. Many animals 
 live upon vegetables, and carnivorous animals live upon animals 
 that live upon vegetables ; so that whatever animal manure you use 
 is really derived from the vegetable kingdom. 
 
 In the case of farm-yard dung, you simply return for the pro- 
 duction of new vegetables what formed part of the old. You only 
 replace on the land what you have taken from it. According 
 to the circumstances in which you happen to be placed, you make, 
 in various ways, farm-yard dung out of vegetable matter. Some 
 persons put a quantity of straw in a yard, turn in a number of cat- 
 tle, and there supply them with food. The cattle tread the straw 
 about, and after it has become a little decomposed it is called 
 farm-yard dung. Others, again, feed their cattle, in boxes, with 
 oilcake, and hence we have another variety of dung. But, what- 
 ever the process may be, you will find that the dung is neither 
 more nor less than materials which once grew on the land ; materials 
 which, having once had vegetable life, are put on the ground again 
 to sustain that life. It is a simple, but most important fact, that
 
 24 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 what once formed part of a vegetable can become part of a vegetable 
 again. 
 
 In the management of farm-yard dung there are a few things 
 worth noticing. Some of the constituents of frfrm-yard dung are 
 volatile, and go into the air; others are soluble in water, passing 
 away if there is too much water; while the most worthless are the 
 least volatile and the most insoluble. Ammonia, one of the most 
 valuable constituents of all manures, is that which is the most 
 volatile, and if you allow too great heat in the decomposition of 
 vegetable manures, the ammonia, as it is produced, is driven off into 
 the air. Again, if as is the case, I am afraid, rather too much 
 even in this part of the country you allow all the water that falls 
 to go upon your manure, even that which comes from buildings 
 and out-houses, you wash away all the soluble materials; and dung 
 that has parted with these volatile and soluble materials is like so 
 much green thatch it is not more valuable, and produces no better 
 results. If you want to buy pure ammonia in the commercial mar- 
 ket, you must pay at the rate of sixty pounds a ton for it, in any 
 manure in which it is to be found ; and if you want to buy phos- 
 phates and other materials of that kind, you must pay a very high 
 price for them. You should, therefore, be very careful to prevent 
 waste. One of the best methods of preventing the waste of ammo- 
 nia, where you cannot put dung on the land at once, is to make 
 compost heaps of it in fact, nitre-beds. I have seen to-day, while 
 riding out near Driffield, a quantity of dung without the slightest 
 covering upon it ; a large proportion of it having been exposed to 
 rains, which must have washed away the ammonia, the nitre, and 
 everything else in it that was useful. I asked the man why he did 
 not lay it up, and put a layer of ditch-stuff upon it. He said, " Per- 
 haps it would have been better, Sir." This, however, had not been 
 done. If the farmer had made a layer of road-stuff, of which there 
 are hundreds of loads within a few yards of the field then put one of 
 dung, then more .road-stuff or soil, and so on, covering the whole 
 with the earthy matter he would have had a complete nitre-bed; 
 he would have had the whole of the earthy matter impregnated with 
 the gases given off by decomposition ; and he would thus have se-
 
 NATURE AND APPLICATION OF MANTJEES. 25 
 
 cured a much more valuable manure than the washed dung which he 
 is now putting on his land. This nitrification can be always carried 
 on by you, gentlemen. There are times when you cannot put dung 
 upon the land ; and what are you to do then ? The best thing is to use 
 some calcareous matter marl or something of that kind, and to lay 
 the dung up in such a form as to be easily mixed with it ; turning 
 the mass over once every two months. The earthy matter will pre- 
 vent its being too light, and also prevent too great decomposition. 
 The grand point is to guard against decomposition going too far : 
 you should take care to let it proceed slowly and regularly. 
 
 There are many who like well- rotted spit-dung. Were I going 
 to buy this at so much per ton, I should probably seek that which had 
 been rotted for some time ; but if I made my own, I should proceed 
 very differently. A hundred tons of new dung are certainly more 
 valuable than a hundred tons of the same dung rotted down to 
 fifty tons ; but, on the other hand, a ton of the fifty may be worth 
 more than a ton of the hundred, and therefore, though I might be 
 inclined, when buying dung, to prefer that which is well rotted, 
 it does not follow that I should rot it down myself. In the 
 case, therefore, of lands not over light, which would not be injured 
 by long straw being put on them, fresh dung is the most ser- 
 viceable ; a hundred tons of fresh dung would do more good upon 
 such land than a hundred tons of the same kind of dung wasted 
 down by decomposition to seventy, sixty, or fifty tons. I cannot 
 too much impress upon you the necessity of preventing too great 
 decomposition from taking place ; unless you put something to 
 absorb the gases given out, so as to form a species of nitre- 
 beds. 
 
 Farm-yard dung, as I told you before, essentially varies in value 
 according to the substances from which it is made. If you prac- 
 tise box-feeding if you feed your bullocks in boxes, you should 
 follow Mr. Warne's plan. If you feed with linseed, and other 
 strong food, the manure ought not to be exposed to the wet, but 
 should be stacked up I was going to say, as you would stack up 
 barley or mixed with soil as before described. Some covering 
 should always be over it ; and if that were done in the way I have
 
 26 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 mentioned, calcareous matter being mixed with the manure, you 
 could make manure which would act, proportionately, quite as 
 strongly upon your land as any nitrate of soda which you could 
 use. 
 
 There now arises a question as to the general application of 
 farm-yard dung to different crops. I had better, in speaking of 
 that, just mention that in all lands there ought to be a crrUiin 
 amount of lime. Though you are living upon the Wolds, which 
 is quite a chalk district, I must tell you I have known very good 
 results arising from putting chalk upon chalk. In Hampshire, and 
 in various counties where the Downs have been exposed for years 
 and years, 1 have taken some of the soil within a few inches of the 
 surface, and tested it for chalk, and have scarcely found a trace ; and 
 having recommended gentlemen there to lime or chalk these Downs, 
 whichever might be the best and cheapest, my recommendation was 
 followed, and in the result was productive of an increase of verdure. 
 It does not follow, that on the very surface of a chalk or limestone 
 soil, you should have chalk or limestone. There is a tendency in 
 chalk and limestone to go downwards. If, a few years after a field 
 has been limed, you dig it, you will probably find a layer of the 
 lime some inches below the surface. In some of the hop-fields in 
 Kent, where the hops grow upon limestone rock, I have taken the 
 surface of the soil, and have not found one part in a thousand of 
 carbonate of lime. I therefore recommend chalk or lime upon 
 soils known to be formed of limestone itself; because of the general 
 tendency of calcareous matter to be washed downwards. 
 
 Let me say one word with respect to the application of 
 farm-yard dung in general, before I speak of the so-called 
 artificial manures. How should it be applied ? Some apply it 
 to wheat, some to grasses some to one crop, some to another. 
 There has been a great dispute in the south as to whether farm- 
 yard dung should be applied for wheat directly in the autumn or 
 whether it should be applied upon the grasses. Many advocate the 
 putting of it on the clover at midsummer ; and in almost all cases 
 where it has been so tried it has produced a good effect. I carry 
 that plan a little further, and, instead of applying farm-yard dung
 
 NATURE AND APPLICATION OF MANURES. 27 
 
 for wheat, in ordinary cases, when the wheat' is about to be sown, 
 or on the clovers at midsummer, I apply it in the autumn or spring 
 before, upon the clover. The result of pursuing that course is this : 
 You give the clovers a thoroughly good dressing, so as to enable 
 them to grow with much greater rapidity, and to much greater 
 volume ; you also have a far greater amount of roots produced in 
 the soil ; and the wheat derives a greater benefit from those 
 roots, in the shape of manure, than if you applied the manure at 
 midsummer, or when you plough up the ley in the autumn. 
 Wherever this plan has been tried and it has been tried in many 
 places it has been found efficacious. Experiments have been 
 made, distinctly showing that it is better to apply farm-yard dung 
 to green than to corn crops. 
 
 With respect to arcificial manure, so called there cannot 
 strictly be any such, because, wherever manure exists,, we can 
 trace it all back to natural sources. Bones are known as very 
 efficacious sources of manure, particularly in this district. What 
 are bones ? You get them from animals ; animals live upon plants, 
 and all the constituents of plants come from the earth or the air. 
 Then you have guano. Whence does guano come ? It is the 
 deposit of sea-fowl ; these sea-fowl feed upon fish ; the fish 
 feed upon vegetables in the ocean ; the vegetables in the ocean, 
 under the light of the sun, feed upon minerals and other matters 
 existing in the ocean ; so that even Peruvian guano comes from 
 vegetables. I have here a sample of dried flesh from Buenos Ayres. 
 How is that produced ? It comes from bullocks, of which many 
 thousands are killed for the sake of their hides, which are sent to 
 England. Thirty or forty thousand hides of these wild cattle are 
 imported every year. These animals graze upon the prairies and the 
 pampas of South America, and they get their flesh from the veget- 
 ables on which they feed. The question arises, which is the most 
 valuable of these various manures ? If you examine all those which 
 are found practically to be productive of the greatest benefit, you 
 will find that those which contain the largest proportion of nitrogen 
 or ammonia, and the largest proportion of phosphate of lime, are 
 those which prove of the greatest advantage to the farmer. Theo-
 
 28 LKCTURK8 ON AGRICri/ITR.VL CHKMISTRV. 
 
 retically, we should say that a manure was perfect if it contained 
 every constituent that is found in a plant. That would be, 
 theoretically, a perfect manure, if you intended to grow -plants 
 upon a soil which contained nothing. But, then, if the soil contain 
 certain ingredients ; if it have a certain amount of soluble -silica, 
 potash, soda, and other materials of that kind, which most of the 
 soils of this country have, in that case whatever the soil happens to 
 be most deficient in will of course be found most beneficial ; and 
 it has been proved by experiment, not only here, but in France, in 
 America, and in many other parts of the world, that those bodies 
 which contain nitrogen, and those which contain phosphate of lime, 
 are the most valuable for manure. Now, you know that, do what 
 you may, save your manure as you will, there is a constant loss 
 upon the farm ; that, though you may, by proper working of the 
 soil, get a very considerable amount absorbed from the air, yet there 
 is always a loss that there are few instances in which sufficient 
 manure can be obtained by ordinary farming, and without im- 
 portation from other sources of supply. I assert, generally, that 
 unless you import phosphates and nitrogen, your farms cannot be 
 much benefited by manure. Potash and soda have been used in 
 large quantities, but without any general, or long-continued, distinct 
 effect, except so far as salt is concerned, of which I shall speak 
 hereafter. We have had silicates of soda, and a great variety of 
 other materials, much spoken of; but only those which I have 
 mentioned seem to have been generally productive of good effects. 
 Well, now, in treating of manuring we must take the separate 
 crops, beginning with the turnips, and see what are the best ma- 
 nures for them. I think that, so far as experience has tested the 
 matter, bones have been found in this part of the country, and in 
 almost every other, to be one of the best manures for turnips ; but, 
 then, you have had to put on a large quantity of bones per acre-, 
 and after you have taken your turnip crops you have found a great 
 deal of bone left which has evidently exerted no action at all. It 
 was the celebrated Liebig who suggested that if the bones were 
 made more soluble their action would be quicker, and the expense 
 to the farmer less. He suggested that they should be made soluble
 
 NATUKE AND APPLICATION OF MANURES. 29 
 
 by a process well known to chemists. Bones can be dissolved 
 in a variety of ways, A method which has been known for fifty or 
 sixty years namely, by the use of sulphuric acid was the one re- 
 commended by Liebig. He proposed that sulphuric acid should be 
 applied to bones, so as to dissolve a portion of the lime, and set the 
 phosphoric acid free. This has been generally done, and I believe 
 no suggestion in chemical science has been productive of such im- 
 mense advantages to agriculture as this simple one of Liebig ; 
 because, instead of throwing a quantity of bones upon the land, 
 which apparently are very good for the landlord I say apparently, 
 because he sees the bones there you now put in just as much as the 
 crop requires, and not a farthing's worth more. It ill accords with 
 my notion of what farming in the present day ought to be, that a 
 man should put a sufficient quantity of manure upon his land 
 to last for nine or ten years, losing the interest of his money for 
 the whole of that time. As well might he put 10,000 'into a 
 bank, and keep it there for ten years, simply because he might 
 want to spend a thousand a-year, thereby losing some hundreds 
 a-year of interest during the period. The introduction of artificial 
 manure has inaugurated a new era in the art of farming. Most 
 cotton manufacturers, we know, turn over their money every two or 
 three weeks, and are exceedingly careful not to lay out a penny 
 on which they cannot realise a profit ; and I would impress upon 
 you, that if you proceed on the old system, when you have the 
 means of determining exactly how much manure you require, you 
 are only wasting your capital and losing your interest. You can 
 grow an}' crops you like by attending to this matter. Is it not 
 foolish to administer at once to the soil as much as would suffice 
 fo*r three, or four, or five crops, when the land is subject to all 
 the vicissitudes of rainy seasons, when almost everything solu- 
 ble must be washed out of it ? Instead of a quarter or a 
 quarter and a harf of bones being necessary, as formerly, a few 
 bushels, acted on by a third of their weight of acid, and rendered 
 soluble, will produce not only an equal but a better crop, and 
 some effect may even be seen in subsequent years. 
 
 Artificial manures are valuable in another point of view. You
 
 30 LECTURES ON AORICULTUR.VL CHEMISTRY. 
 
 are not always obliged to feed your turnips off upon the land, but 
 you may want them, in some instances, at home. If, in conse- 
 quence of this, your barley does not, in the spring, look as satis- 
 factory as it ought, you can now improve it, whereas before you 
 were obliged to leave it to its fate. A little guano or nitrate of 
 soda and salt about three quarters of a hundred weight of cither 
 guano or nitrate of soda, and four hundred weight of common salt 
 for either wheat or barley looking badly in the spring, will pro- 
 duce an immediate effect. You will find, particularly in hilly 
 districts, that a great breadth of land not hitherto cultivated for 
 turnips, or cultivated with difficulty, in consequence of the im- 
 mense expense of carrying farm-yard dung, can be brought by 
 these artificial manures into a high stat>e of fertility ; and I need 
 not tell you, that if you get twenty tons of turnips per acre, 
 your cultivation for the next four years will be pretty well estab- 
 lished. In Wiltshire and other places in the south, the introduc- 
 tion of these portable manures has been the actual salvation of the 
 country. In that district farmers with whom I am well ac- 
 quainted have been paying high rents for low-lying lands smaller 
 rents, it is true, for the high lands, but between the two the rental 
 has been considerable. The hills there are rather more abrupt 
 than the ordinary run of hills in this neighbourhood, and it was 
 found exceedingly difficult, indeed almost impossible, to cultivate 
 them ; but since the introduction of portable manures, by the appli- 
 cation of guano, superphosphate, or manures of the same kind, to 
 the hill land, agriculturists have been enabled to obtain a great 
 quantity of turnips, with which they have fed an increased stock of 
 sheep. I have not heard any grumbling from them for the last 
 three or four years ; they have been doing well by their stock ; and 
 if you, gentlemen, can grow more food, and keep a larger num- 
 ber of stock if you can manage to keep an increased quantity of 
 sheep, and sell them at good prices, and also dispose of your wool 
 at lid. or I8d. per pound, I think the cry we have had about 
 the fall of British agriculture will prove to have been perfectly un- 
 founded. 
 
 I have, I believe, given you a pretty clear notion of what are
 
 NATURE AND APPLICATION OP MANUEES. 31 
 
 the best manures for these crops. I may say, generally, that for 
 wheat those manures are the best which contain ammonia or nitro- 
 gen, with a certain amount of phosphates. They must be applied 
 carefully, because there is a liability to throw down the wheat ; and, 
 in order to prevent that, I must recommend you to use salt. Salt 
 is not a thing which shows itself conspicuously in the production of 
 great luxuriance, but rather in giving strength to the stem of the 
 wheat. In Lincolnshire you will rarely find the wheat falling on 
 the salt marshes. Two hundred weight of guano and four hundred 
 weight of salt is a good dressing for an acre of wheat, With respect to 
 grass land, according to the experiments of Professor Kuhlmann, the 
 amount of grass produced on any given acre is in direct proportion 
 to the amount of ammonia or nitrogen used. In reference to grass 
 and clover, you have not much cause to fear excessive luxuriance. 
 The more you apply of those manures which contain nitrogen, the 
 greater will be the production of vegetation. Professor Kuhlmann 
 applied gas-water, nitrate of soda, ammonia, dissolved bones, and a 
 great many other things, to grass land ; and he found, as the result 
 of his experiments, having ascertained previously by analysis the 
 amount of nitrogen in these materials, that the increase of the crop 
 was precisely in proportion to the amount of nitrogen in the ma- 
 nure. He tried the experiment for two or three years. He took 
 not only the first crop, but the second ; he cut them, and found an 
 increase, relatively, in the second as in the first. Having had ex- 
 periments tried on the Downs in Dorsetshire, with ammoniacal 
 manures, I have myself found the production of grass largely in- 
 creased thereby. I mention these things, because you will have to 
 turn your attention a little more to science than you have done, so 
 as to ascertain the nature of the manures which you are using. 
 
 Now let me say a word, in conclusion, with respect to the 
 adulteration of manures. Good guano ought to con tain, sixteen or 
 seventeen per cent, of ammonia, and from twentv-five to thirty 
 per cent, of phosphate of lime : I am speaking of Peruvian guano. 
 There are many other guanos brought into this country, and I will 
 just tell you what they are selling at. Guanos, of which I have 
 had hundreds under analysis, have been selling in the market at
 
 32 LKCTURKS ON AGRICULTURAL CHEMISTRY. 
 
 8 and 9 per ton ; but to you they are not worth a third of that 
 amount. I wish to warn you, that if you procure guano from 
 any but the best sources, it is a thousand to one but you are 
 cheated, as many persons, I fear, have learnt to their cost. It 
 is far better, I should observe, for you to give your orders for 
 manure before than after Christmas, because after Christmas there 
 is nearly always more uncertainty about it. The ships may not 
 come in ; and if the importers know what demand is likely to be 
 made, they will be the better able to meet it. 
 
 Adulterations of guano are carried on to an extraordinary 
 extent. The other day I happened to be in Newcastle, and 
 I can assure you that there is a regular establishment there 
 for the purpose of sending into this neighbourhood, and into 
 Hull, Stockton, and other places, systematically adulterated arti- 
 cles to the extent of thousands of tons. They are sent off 
 quietly, to prevent the trickery from becoming known, and are 
 of course flavoured with a little genuine guano. The adulterated 
 article is bought up by those farmers who like to purchase a little 
 under market price, and who are, in consequence, shamefully 
 cheated. Every farmer, in fact, who tries to buy cheap manure, 
 is sure to be deceived j because, if he will have it cheap, people 
 will be found to make it at his price, and he will have to pay the 
 cost of mixing, and probably fifty per cent, besides. If manures are 
 worth using at all, they are worth a proper price. Manures of the 
 lowest price are the least valuable to the farmer. If he could obtain 
 a manure intrinsically worth 50 a ton, it would be proportionately 
 more valuable to him than Peruvian guano, because of the saving of 
 carriage, and other facilities arising from its small bulk. You can- 
 not, therefore, be too careful in purchasing these artificial manures. 
 I am, myself, extensively engaged at the College in the analysis 
 of manures, and shall be very happy to render to the farmer any 
 assistance that may be required, in certifying him as to the quality 
 of any particular manure. Let me advise you, when purchasing 
 the article, to deal with none but men of established character and 
 integrity. Do not try to buy everything cheap, for it is certain 
 that you will be cheated if you do. The quantity of adulterated
 
 NATURE AND APPLICATION OF MANURES. 
 
 33 
 
 guano annually made up cannot, I think, be less than twenty or 
 thirty thousand tons, and I estimate the lowest amount of which 
 the farmer will thus be defrauded at 100,000 per annum. The 
 adulteration of artificial manures is, however, of sufficient import- 
 ance to form the subject-matter of another lecture.
 
 34 LKCTUKES OX, AGRICULTURAL CHEMISTRY. 
 
 THE ADULTERATION OF ARTIFICIAL MANURES, AND 
 THE BEST PRACTICAL MEANS OF DETECTION. 
 
 THE subject which I have the honour of introducing to your notice 
 this evening, is, I think, almost as important a one as can at this 
 time be brought under the consideration of practical farmers. The 
 time is past when farmers were compelled to depend for their 
 manures solely upon those articles which they produce upon 
 the farm. By practical analyses of the manures used in culti- 
 vation, it has been found that certain substances constitute the 
 chief ingredients which are capable of giving fertility to the soil ; 
 and, as you are well aware, numerous other substances, either 
 obtained from our manufacturers or brought from abroad, such as 
 nitrate of soda and guano, are used for the purposes of agricultural 
 improvement. It is of immense importance that the articles thus 
 brought to your farms should be received by you in a state of in- 
 tegrity, and that if adulterations are carried on, you should have 
 in your hands the means of detecting them, and of avoiding the 
 loss which you might otherwise sustain. 
 
 I shall endeavour, gentlemen, in this lecture, to show you of 
 what good manures consist what are their principal consti- 
 tuents, and afterwards to give you the whole history of the 
 adulteration of manures, showing you how and where it is prac- 
 tised. I do not mention the names of parties, it would not be 
 prudent to do so; but I shall give you such evidence as to the 
 extent of adulteration as will, I hope, lead every farmer to be 
 very cautious in what quarters he buys manures.
 
 ADULTERATION OF ARTIFICIAL MANURES. 35 
 
 Now let us examine, in the first place, in what the value of 
 manure consists. It is quite evident that if manures be useful in 
 eliminating and bringing forth the elements of the crop, and tend 
 to produce luxuriance, the cause is not to be found in every ingre- 
 dient alike, but in some one or two of the constituents. You are 
 well aware that the old staple manure was farm-yard dung. Farm- 
 yard dung is the result of the decomposition of vegetable matter, of 
 materials originally derived from the soil and the air; the vegetables 
 deriving one portion of their nutriment from the soil and another 
 from the air, the two combining by the action of solar light. When 
 these vegetable substances are put on the land, whether they are 
 eaten off by sheep and bullocks, or ploughed in, you get certain 
 elements in the land which serve the purpose of manuring ; in other 
 words, substances which once sustained vegetable life, again sus- 
 tain it when they have undergone sufficient decomposition. 
 
 This being the case, we must inquire which of the constituents 
 found in these manures and crops are the most valuable. I need not 
 tell you that the money value of a thing depends much on the diffi- 
 culty of obtaining it. If diamonds were found scattered about the 
 road, their value would be no greater than that of flint or granite; it 
 is the difficulty of obtaining them which so enormously enhances 
 their price. Now you have in farm-yard dung, first, a large amount 
 of water. The common dung which is put on the farm, and which is 
 so highly prized by the farmer, con tains seventy, eighty, and, in some 
 cases, even ninety per cent, of water. It is evident that, as the air 
 of heaven continually furnishes us with a large amount of water in 
 the form of rain and dew, this constituent ought not to be regarded 
 as very valuable in manure. It is, in fact, just the contrary. The 
 wetter the manure, the worse it is. To go a little further; what 
 is the least valuable ingredient after water ? Here we come to car* 
 bonaceous or mere woody matters. These are absolutely required 
 when you are farming on a large scale ; and in putting on twenty 
 or thirty loads of dung per acre, you apply a sufficiently large 
 amount of carbonaceous substances to be of great value in the field, 
 In so doing you act quite correctly ; but when you put three 
 hundred weight of guano against fifteen or twenty loads of farm-
 
 36 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 yard clung, the equal effect of the guano must be owing to some- 
 thing more than the mere carbonaceous materials. It is not these 
 alone which do you service; for the proportion contained in guano 
 is very small. One ton of guano contains only eight or nine hundred 
 weight of carbonaceous matter, which cannot be the great staple 
 of manures; and, although it may be useful to put this on the 
 land, either by ploughing it in or by applying it in the shape of 
 straw, yet I cannot set any great value on this alone it is equiva- 
 lent to so much saw-dust ; and the putting of a large quantity of 
 decomposed sawdust on the land would produce equal effects. 
 When I speak of the application of carbonaceous matters, I 
 do not refer to charred materials ; because in that case a change 
 has taken place, and the matter has acquired other properties. 
 To mere woody organic matter, then, I say, we cannot properly 
 attach any considerable value. Again, common salt is found 
 in farm-yard dung. 'We may, perhaps, find one per cent, of that 
 ingredient ; but this proportion is too small to be highly prized. 
 I might go on to allude to various other ingredients; but if I 
 did so, it would all resolve itself into this that the nitrogen, and 
 the phosphate of lime or bone earth, constitute the elements of 
 chief value in artificial manures. 
 
 Now in farm-yard dung, so far as I am able to judge and my 
 opinion has been corroborated by that of many others there is 
 seldom one per cent, of ammonia, though in the case of the dung of 
 animals which have been highly fed, you may get a little more; 
 and hence it is that you require to put so large an amount of sucli 
 unconcentrated manure on the land. There are other manures 
 which contain a much larger proportion ; for example, guano, 
 various kinds of night-soils, and urines. Numerous experiments 
 ill my laboratory give an amount of nitrogen^ in guano, equal on 
 an average to seventeen per cent, of ammonia. Now, nitrogen, 
 either in the form of ammonia or of nitrates, is the most im- 
 portant and expensive element of manures. Ordinary Peruvian 
 guano has likewise from eighteen to twenty-two per cent, of 
 phosphate of lime. This is also valuable : it is, as you are 
 aware, in the shape of superphosphate of lime, one of the best
 
 ADULTERATION OF ARTIFICIAL MANURES. 37 
 
 materials for the turnip crop. It has been well ascertained 
 by analysis, that the turnip contains a considerable amount of 
 phosphate of lime. When turnips have been put upon the 
 land without the application of it, they have scarcely grown to 
 the size of a radish ; whereas, the use of a sufficient quantity 
 of this substance has led to a crop of from twenty to thirty 
 tons per acre. It is, therefore, on the presence of ammonia 
 and phosphate of lime that the value of manure principally 
 depends ; and when we know the quantity of those articles which 
 exists in any given case, we shall be capable of forming a tolerably 
 good estimate. You may reckon the price of ammonia, in guano 
 and other substances, at sixpence per pound. Most chemists 
 have given testimony to this effect ; so that if you only have an 
 analysis of guano, and divide the number of pounds of ammonia 
 per ton by two, you will get the price in shillings, and will thus 
 obtain the actual value of the ammonia. 
 
 The value of phosphate of lime may be stated at three farthings 
 per pound, in some cases it may be a little more; but, if any 
 person should pay three farthings per pound, he would, I think, 
 have no reason to complain. As to the other constituents of 
 guano, it is very easy to ascertain their value. We all know what 
 is the price of salt in the market, and if we find that a certain 
 manure contains four per cent, of salt, we may, of course, easily 
 calculate what that amount is worth. It cannot be necessary that 
 I should dwell on this point. Sulphuric acid also is found in 
 guano and other manures; and, there again, it is not difficult to form 
 an estimate of value. We must not, however, take the price of the 
 highest compounds when we make our calculation, but must 
 take some substance containing sulphuric acid, as sulphate of lime 
 or gypsum, which has a low price in the market. Gypsum is from 
 twenty to twenty-eight shillings per ton, so that the small quantity 
 of sulphuric acid contained in guano cannot be of great value. 
 Without the slightest difficulty, therefore, I repeat, we can form a 
 tolerably accurate estimate, for commercial purposes, of any ordi- 
 nary manure. I do not say absolutely accurate, but sufficiently so 
 for the purpose required, the composition being known, for of 
 
 p
 
 38 J.Ef'TUKKS OX AOUICUJ.TURAL CHKMISTKY. 
 
 course, without such knowledge as that it is impossible to tell the 
 value. 
 
 Now before leaving the subject of guano, let me just mention 
 its origin and sources. Guano is obtained from deposits of the 
 dung of birds which have fed upon fish. It is not confined to any 
 one quarter of the globe ; it is not limited to South America, 
 but it is found in all latitudes where great flocks of birds congre- 
 gate and deposit their fasces, and where the rain and wind do not 
 carry these away. In many places this manure is now being collected 
 by hand. Instead of its being allowed to accumulate for a number 
 of years, persons are employed in gathering it year by year; and 
 it is now being deposited in many places to a sufficient extent to 
 render this process of collection very profitable. The newly-de- 
 posited guano is found to contain in some instances more than 
 twenty per cent, of ammonia. As regards the guano found in the 
 island of Chinca and in other islands on the coast of Peru and Boli- 
 via, these have been deposited for ages. Hundreds of years ago, 
 guano was used in Peru in the cultivation of the soil ; and it always 
 secured exceedingly good crops. It is, in fact, merely the faecal 
 matter of birds. This natural substance must vary considerably in 
 its composition. Where there has been little or no rain, you 
 have it in a state of purity ; but on the islands to the north or 
 south of the dry latitudes it is found more or less deteriorated by 
 water ; the soluble materials are in that case lessened in amount, 
 the ammoniacal salts are to a great extent washed away, and the 
 proportion of insoluble materials is increased. This effect is 
 palpable in the case of the Saldanha Bay guano, in which, instead 
 of fourteen or sixteen per cent, of ammonia, you have one and a 
 half or two per cent., and fifty to sixty per cent, of phosphate of 
 lime, a substance not very soluble in water. It is, then, quite 
 clear that guano from different quarters of the globe differs very 
 much according to the influences to which it may have been 
 exposed. Even guanos obtained from the same island may differ 
 in quality. Those which have been most exposed will be found of 
 less value than those which have been covered up and not subjected 
 to atmospheric action.
 
 ADULTERATION OF ARTIFICIAL MANUKES. 39 
 
 Ammonia and the other soluble compounds of nitrogen ac on 
 plants in a very similar manner, and producing, as they do, a very 
 great luxuriance of growth, they require to be used with prudence 
 and judgment, especially in the case of corn crops. Many far- 
 mers have suffered great loss from the use of too large quantities 
 of guano, or of nitrate of soda, on wheat and barley ; the corn 
 having been lodged before harvest, and the crop in many instances 
 totally spoiled. With grasses and other plants which require luxu- 
 rious growth, these manures maybe used with advantage to a much 
 greater extent, and the increase of weight in the crop will be 
 almost always in proportion to the amount of nitrogen in the 
 manure, supposing, of course, that the land is well supplied with 
 mineral ingredients. Kuhlmann made some very interesting ex- 
 periments on grass land, where nitrate of soda and sulphate and 
 other salts of ammonia were applied in known quantities. The 
 result was, that the increase in the crop was always in direct pro- 
 portion to the nitrogen applied that is, twenty pounds of nitrogen 
 per acre, whether applied as nitrate of soda or as sulphate of 
 ammonia, gave double the increase of ten pounds of nitrogen per 
 acre. This is an important fact, and advantage should be taken of 
 it for increasing the quantity of green food, and consequently the 
 amount of stock upon our farms. As common salt has a direct 
 tendency to strengthen the straw of our grain crops, it may be very 
 judiciously used for that purpose with guano and nitrate of soda. 
 The chances of the corn lodging are thereby greatly decreased; A 
 mixture of four hundred weight of salt, and from three quarters to 
 one hundred weight of nitrate of soda per acre, will be found an 
 excellent spring dressing, on light lands, for sickly-looking young 
 wheat, or for barley. About two hundred weight of Peruvian guano 
 and four hundred weight of salt are also an excellent dressing for the 
 heavier descriptions of soil. 
 
 One of the best known artificial manures is, I need hardly say, 
 bones. That bones must be beneficial as manure will appear from 
 a very simple consideration. Animals are fed upon vegetables, and 
 the whole of their bodily structure grows out of the food, or is 
 eliminated and formed from it. If the food did not contain phos-
 
 40 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 phate of lime, the bony structure of the body could not be built 
 up: if the soil in which vegetables grew did not contain phos- 
 phate of lime, the seeds of vegetables could not be matured. 
 Supposing the arable land of this country to have been robbed 
 for a thousand years of phosphate of lime, and never to have 
 received any back again; supposing this article to have been 
 continually exported in the shape of milk, cheese, sheep, and oxen, 
 it is clear that unless the land had almost an unlimited amount of 
 phosphates, which we know is not the case, there must have been a 
 proportionate diminution in the quantity of these materials. Hence 
 it is, that when certain substances which had been taken out for a 
 long period have been again suddenly applied, land which was 
 hardly worth five shillings an acre has sprung up to the value 
 of fifteen shillings, and there has been an enormous increase 
 of crop. For a long period, for example, we had been rob- 
 bing our land of gypsum ; and when this material was first 
 brought into use, and applied to the soil, almost miraculous re- 
 sults followed. So, likewise, on the first application of properly- 
 ground bones in this country, the effects were quite marvellous. 
 Bones are valuable for two reasons on account of the phos- 
 phate of lime they contain, and on account of the nitrogen, 
 which becomes ammonia as the bone decomposes in the soil. Some 
 chemists assert that bones contain six per cent, of nitrogen ; but that 
 has not been the result with any of the bones that I have analysed : 
 probably four per cent, would be nearer the mark. I may as well 
 mention the adulteration of bones at once : I shall afterwards have 
 to speak of the adulteration of guano. Bones are not received 
 by you in their original and entire state, because they would in 
 that case be of little use to you. As farmers, you do not 
 possess mills for the purpose of grinding them, and you are there- 
 fore obliged to entrust other persons with the work of reducing 
 them to a proper state for the land. Now it would be well if 
 parties who ground bones ground nothing else ; but it does so 
 happen that a great many other things are ground up with them, 
 in order that farmers may buy an adulterated article, apparently at 
 a much less cost, but in reality at a much greater, than that for which
 
 ADULTERATION OF ARTIFICIAL MANURES. 41 
 
 they could buy a genuine one. I speak from my own personal 
 experience, when I assert that the bones ground in London, and in 
 many other places, are often mixed in large quantities with oyster- 
 shells. These oyster-shells have the property of splitting up into 
 nice fragments, and unless a gentleman takes out his glass and 
 examines them curiously, with the view of discovering bits of 
 mother-of-pearl, he will probably be unable to discover that he 
 has bought a spurious article. There is frequently from twenty 
 to twenty-five per cent, of this adulterating material ; and, of 
 course, so long as farmers will patronise dealers without reference 
 to character, and make price the sole consideration in purchasing, 
 so long must they expect to get oyster-shells instead of bones. 
 But this is not the only material which is used in adulteration. 
 Soap-boilers' waste and sandy and earthy matters are also introduced. 
 Oyster-shells and soap-boilers' waste contain large quantities of 
 carbonate of lime. If, therefore, the farmer makes his own super- 
 phosphate of lime, he will experience a double loss ; for, until all 
 the carbonate of lime has been acted upon by the acid, no super- 
 phosphate is formed. As carbonate of lime, or chalk, requires about 
 its own weight of sulphuric acid to drive off the carbonic acid, 
 it follows that bones adulterated with twenty-five per cent, of 
 oyster-shells or waste would require five hundred weight of extra 
 acid per ton of bones to neutralise the lime before any super- 
 phosphate could be formed. 
 
 Now there is another manure which has lately come into 
 use, or at least has been brought prominently befo-re the public 
 I refer to peat charcoal. We have had a few trials of this 
 material, though not enough to give evidence of all its pro- 
 perties, and to show how far it is available for agricultural im- 
 provement. Probably, however, it will prove a very valuable 
 adjunct, and will be extensively used, if it can be supplied at a 
 reasonable rate. This charcoal has, like charcoal generally, a 
 considerable power of absorption. It may be applied to sewage 
 with good effect, as it arrests the escape of noxious gases. 
 But in the use of it in connection with night-soil, there is one 
 thing which it is especially necessary to bear in mind, namely, that
 
 42 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 some sulphuric acid should be mixed with the charcoal when 
 removed, as there will otherwise be a slow escape of the ammonia pre- 
 viously absorbed. This is caused by the gradual action of the air, 
 which replaces the ammonia in the pores of the charcoal as the 
 watery vapour is driven off; and it would be very easy to stop this 
 action by means of a certain amount of sulphuric acid. It is 
 difficult to calculate the- value of night-soils and urines, because of 
 the great quantity of water contained in them. If you could get 
 them in a dry state, they would perhaps be the most valuable 
 substances in the world ; if you could by any means, such as pass- 
 ing the urines through charcoal, get rid of the aqueous material, 
 they would answer very well ; but it is difficult to do that merely 
 by mixing them with charcoal. From experiments which I 
 have tried, it is perfectly clear that a certain quantity of peat char- 
 coal, having urine filtered through it, will, when dried with sulphuric 
 acid, retain from four to five per cent, of ammonia, which would con- 
 stitute it a valuable manure. There can be no doubt that if this 
 substance were put under our friend Mr. Mechi's sheep or bullock 
 lattice, and if the f'secal matter were allowed to pass through the 
 lattice, and fall upon it, such a carbonised manure would be found 
 of great benefit to the agriculturist. I must, indeed, distinguish 
 this carbonised material from mere organic matter, which has not 
 the same power of absorption. If you took one hundred weight of 
 straw and carbonised it, it would afterwards have a much greater 
 power of absorption than it had while left in its natural state. 
 
 I will now fepeak of the nature and extent of the adulterations 
 to which guano and similar substances are exposed. We have seen 
 clearly that the value of guano and other artificial manures de- 
 pends pretty much on their ammonia and phosphate of lime; it 
 cannot depend on a given amount of sand, or loam, or brick-dust, 
 or ground tiles, or any article of that kind, which may be mixed 
 with it; and it is one main object of my lecture, to bring palpably 
 before the practical farmers present a glimpse of the fearful extent 
 to which adulteration is now carried, though it must be very 
 inadequate when compared with the reality. I feel perfectly in- 
 capable of showing one hundredth part of the actual extent of this
 
 ADULTERATION OF ARTIFICIAL MANURES. 43 
 
 evil. Gentlemen, you are robbed systematically. It is not simply 
 that a little country dealer buys his ten tons of guano, mixes some 
 foreign matter with it, and then sells it as genuine; there are men 
 who make hundreds and thousands of tons of materials for adulter- 
 ating guano, which are sold in the market for the express pur- 
 pose of adulteration. It is a general system, beginning, in the 
 metropolis, and extending over the whole country. Even the 
 country cheaters are themselves cheated in turn. The men who 
 come to London to buy their manures very often get an adulterated 
 substance ; the article passes through the hands pf half a dozen 
 parties before it reaches the farmer, and when at last it does reach 
 him, it is in an extraordinary state of adulteration, very little in- 
 deed of the original matter being discoverable. Guano ought not to 
 contain more than one and a half to two and a half per cent, of sand ; 
 besides which there should be at least twenty per cent, of phos- 
 phate of lime, from sixteen to seventeen per cent, of ammonia, and a 
 considerable quantity of organic matter. Now you can buy 
 guanos in the market, containing from sixteen per cent, of am- 
 monia, which is a good genuine article, down to others containing 
 only a trace. It grows "small by degrees, and beautifully less," 
 until you have got a thing which contains little else than our good 
 Essex marl, from the Wanstead Flats, or some other place, with a 
 little guano mixed with it to give it the right smell. Another 
 adulterating substance is ground marl from Bow Common. 
 
 In fact, the whole system of adulteration is so well devised, 
 that, without an analysis, it is almost impossible for the farmer, or 
 the ordinary country dealer, not to be imposed upon. In some 
 cases the buyer has seen his guano taken from the ship's side, and 
 has congratulated himself that he was too cunning to be taken in ; 
 but, unfortunate man ! he had quite overlooked the Essex marl or 
 ground tiles concealed in the barge that it might be well mixed 
 with the guano as it went up the river to the appointed wharf. 
 Some parties have three or four wharves for shipment in various 
 parts of the river, and the same adulterated material is often sent 
 even to the same buyer as two or three separate guanos at different 
 prices. Of course those purporting to be different are shipped to
 
 44 
 
 LECTURER ON AGRICULTURAL CHEMISTRY. 
 
 the buyer from different wharves. The two following analyses 
 will give some idea of the adulterations carried on in the manure 
 market: No. 1, came into the London market, per ship, from 
 Liverpool. It was offered for sale by sample, in some places as 
 Peruvian guano, at 6 10s, to 7 per ton : in others, as Saldanha 
 Bay guano, containing sixty per cent, of phosphate of lime, at 4 
 to 5 per ton. The samples were contained in bags of blue paper, 
 purporting to come ex some ship from Valparaiso. About one 
 hundred and fifty tons were brought into London, the greater part 
 of which found its way to the farmers of Hampshire, no doubt to 
 their great edification and benefit. No. 2 was offered for sale as 
 Saldanha Bay guano, at 3 or 4 per ton. 
 
 No. 1. Guano. (?) 
 
 Gypsum 74-05 
 
 Phosphate of lime 14-05 
 
 Sand 2-64 
 
 Ammonia 0'51 
 
 Moisture and loss . 8-75 
 
 100-00 
 
 No. 2. Saldanha Say Guano. (?) 
 
 Sand 48-81 
 
 Phosphate of lime 10-21 
 
 Gypsum 5-81 
 
 Chalk 22-73 
 
 Moisture 12-44 
 
 100-00 
 
 Now I will exhibit here a few of these samples of counter- 
 feit guano, for the way in which they are got up for sale is really 
 very ingenious. I want the opinion of some of the best-informed 
 gentlemen here as to which of these samples fs the best. [Mr. 
 Nesbit then handed to the Chairman specimens of two kinds of 
 guano, requesting him to state, after examining them, which he 
 would pronounce the best. The Chairman having selected the one 
 which he conceived to be the best, the Lecturer continued.] Well, 
 now, this which our Chairman has selected as the best guano, is the 
 one which is adulterated ; and it contains nearly half its weight of 
 Essex marl. [The Lecturer then exhibited in a bottle the propor- 
 tion of sand to' genuine guano in the two samples, showing that in 
 the guano which the Chairman had considered the best, the sand 
 and other worthless insoluble materials constituted more than one 
 half of the whole.] In the guano which our President thought 
 best, there is 52.8 per cent, of sand, though it was sold as genuine.
 
 ADULTERATION OF ARTIFICIAL MANURES. 45 
 
 The mode of mixing this sample is clever and peculiar. The 
 whole of the guano and marl are not mixed together at once, 
 but the large lumps being picked out of the genuine guano, 
 the small is thoroughly mixed with the marl, and then the 
 unbroken large lumps of guano are carefully added so as not to 
 break them. The whole, therefore, has very much the appearance 
 of good guano ; for the lumps in the mixture are merely the 
 guano unadulterated. Here is another specimen [exhibiting 
 it], in which I found 54 per cent, of insoluble matter. Let 
 me now show you the proportion of insoluble matter which 
 is contained in genuine guano. This contains only eighteen 
 grains in one thousand, or 1.8 per cent. Remember, gentle- 
 men, in future, that the strongest-smelling guano is not always 
 the best. You cannot tell whether or not it be genuine either by 
 the smell or by the colour. In fact, the only means by which you can 
 ascertain the truth of the matter is by analysis. I will, however, 
 show you one mode of detection which will serve your purpose so 
 long as the adulterators continue to act upon the present sj'stem. 
 They now adulterate with a heavy article. If you take five hundred 
 grains of the best guano and five hundred of an adulterated article, 
 and put each into a tube of the same size, you will find the adul- 
 terated article much lower in the tube than the genuine one. Here 
 is an illustration. [The Lecturer here exhibited two tubes, contain- 
 .ing respectively the same quantity of adulterated and genuine 
 guanos, the latter reaching far higher in the tube than the former.] 
 The presence of the sand is shown at once by the comparative 
 smallness of the space which it occupies. 
 
 I must now show " THE ARTICLE " itself the material for 
 adulteration it is known in the trade as " THE ARTICLE." It can 
 be bought for the purpose of adulteration at from 10*. to 20s. per 
 ton. There may, perhaps, also be ten or twenty per cent, off for 
 cash. I hold in my hand, gentlemen, five hundred grains of " the 
 article." [The Lecturer here exhibited in one tube five hundred 
 grains of "the article," and in a similar tube five hundred grains of 
 genuine guano,] You see "the article " presents a very sorry appear- 
 ance by the side of the genuine guano. Observe the amount of
 
 46 LECTURES OX AGRICULTURAL CHEMISTRY. 
 
 silica which it contains, and then judge what is the extent of 
 adulteration. I must, if possible, compel the attention of all pre- 
 sent to this wholesale system of adulteration. It is not, you see, 
 confined to one or two small houses, but the trade in this article is 
 as regular a branch of business in the metropolis as the trade in 
 guano itself. How does this arise ? Whence comes all this adul- 
 teration ? It is partly owing to the fact of the farmer's nibbling 
 and haggling to get the last penny of profit out of the dealer's 
 hands. He has thus been compelling those who would perhaps 
 otherwise be honest, to sell an article like that which I have been 
 exhibiting. 
 
 This is not buying in the cheapest, but in the dearest market. 
 Let me here observe, that it is quite impossible for persons who 
 have once begun to adulterate to do so to a small extent. No man 
 can adulterate merely to the extent of ten per cent. ; it would not 
 pay. In the first place, an article has to be purchased and worked 
 up, and made to look something like guano ; then there is the mix- 
 ing of this article with the guano. The whole process is expensive ; 
 and every particle of the cost, with a large profit superadded, must 
 be paid by the farmer who buys the adulterated article instead of 
 the genuine one. The probability is, that he does not get in 
 return for his money more than one fourth or one third of guano ; 
 but all the rest is sand, or ground tiles, or loam, the carriage of 
 which is, of course, another item of cost to the farmer. 
 
 I have often remarked that if it were possible for chemists 
 to concentrate manures so that they would be worth even 
 50 a ton, it would be an immense advantage to those who 
 have to use them. If guano, for example, could be concen- 
 trated four-fold, it would for that very reason be the most va- 
 luable manure the farmer could use ; since, being of small bulk, 
 the cost of carriage would be decreased four-fold. To return, 
 however, from this digression. I was observing that it would not 
 answer a dealer's purpose to adulterate to the extent of ten I 
 might even say twenty per cent. ; nor, indeed, do dealers confine 
 themselves to such a small proportion. These adulterated ma- 
 nures are sold, some at 5, some at 6, some at 8 per ton. The
 
 ADULTERATION OF ARTIFICIAL MANURES. 47 
 
 best of them are adulterated more than forty per cent. ; and in many 
 cases the adulteration is as much as sixty or eighty per cent. 
 
 It remains for you, gentlemen, to attempt to put a stop to this 
 imposition. I can scarcely offer any other practical means of detec- 
 tion than that which I have just mentioned that of observing and 
 comparing the different degrees of specific gravity or bulk of the sam- 
 ples. Let me tell you, too, that even if you do buy of a first-rate 
 party, it is still possible that you may be deceived. I will quote Dr 
 Anderson's opinion on that point ; and the extract will show that 
 even parties who wish to sell a genuine article are often misled. 
 In an article on guano, in the " Royal Highland Society's Journal," 
 he says : " All the risk and uncertainty to which the farming 
 public is now subjected might be avoided, if buyers would give up 
 seeking for cheap guano, buy from dealers of character, and insist 
 on their purchase being guaranteed of the same composition as a 
 sample analysed by some chemist of known accuracy. It must, 
 however, be distinctly understood that all these precautions are 
 necessary, for there are such things as selling guano by fictitious 
 analysis ; and I have known instances in which dealers of the 
 utmost respectability, and altogether above the suspicion of fraud, 
 being in the habit of selling guano without analysis, have bought 
 in the same way, and have become the unconscious instruments of 
 introducing a grossly-adulterated article into commerce." 
 
 I say, then, that even respectable parties may be deceived. There 
 are gentlemen in the trade who would, I believe, scorn either to 
 adulterate or to sell an inferior article as the best ; but even these 
 gentlemen may be deceived. Still one way in which you should 
 endeavour to secure yourselves is by dealing with first-rate men 
 men who have a character to lose, and who are not, therefore, 
 likely to adulterate. At the same time, I must confess that I see 
 no effectual security except that which consists in your having 
 samples of the bulk you buy analysed. Look at Scotland. The 
 Scotch farmers have their samples analysed, and the bulk tested ; 
 and they have often recovered damages when the two have not cor- 
 responded. 
 
 Other manures are also adulterated in similar ways. Nitrate
 
 48 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 of soda is mixed with a well-prepared sulphate of magnesia, 
 or Epsom salts, whose crystals are almost undistinguishable by 
 the eye from the crystals of nitrate of soda. Sulphate and other 
 salts of ammonia are also much adulterated. There are, in fact, a 
 thousand ways of adulterating manures ; and you can scarcely ever 
 be sure, under present circumstances, that you are applying to your 
 land a really genuine article. Take superphosphate of lime. If you 
 do not buy from a respectable house, you will be sure to have large 
 mixtures : fifty per cent., and in some cases seventy-five, of worth- 
 less material being mixed with the genuine substance. 
 
 I have letters from various gentlemen, including Professor 
 Calvert of Manchester, and Professor Anderson of Edinburgh, all 
 corroborating the fact of the immense adulteration of artificial 
 manures. They have all analysed samples of guano which have been 
 highly adulterated. Professor Calvert informs me that he has ana- 
 lysed some which contained from seventy to eighty per cent, of 
 sand. 
 
 I must now mention a recent attempt to obtain money from 
 the public, of so presumptuous and ridiculous a character, that I 
 hardly know how to allude to it ; I mean the fertilising of seeds. 
 Many years ago it was proposed to steep seeds of various kinds in 
 solutions of manure, or to roll them in some manuring powder, which, 
 adhering to the seed, would render good service in quickening its 
 germination and promoting its early growth. There is nothing 
 unreasonable in this, and in many instances some good has been 
 done by the process. But within a few years, both here and in 
 France, parties have come forward to do away altogether with 
 ordinary manuring, and to give such a coating to the seeds as will 
 carry them well through till harvest. Yes, gentlemen, your 
 boasted farm-yard dung, your Peruvian guano, your superphos- 
 phate of lime, are now, by the " discoveries of science," rendered 
 wholly useless ! Only put three or four pounds of a powder 
 over the seed for an acre of land, and you may then, with your 
 hands in your pockets, joyfully await the hundred-fold increase of a 
 teeming harvest ! Now, in the first place, I as a chemist should 
 condemn the thing at once ; and as to you practical men, I should
 
 ADULTERATION Of ARTIFICIAL MANURES. 49 
 
 think you must be of the same opinion as the Scotch farmer, 
 who, when the laird remarked to him, " Donald, the time will 
 come soon when we shall be able to carry the manure in our 
 snuff-box," replied, " Yes, but when that time comes we shall be 
 able to carry the crop in our waistcoat pocket." We have been 
 told that most astonishing results have arisen in France from the use 
 of fertilising powder on seeds. Being a corresponding member of the 
 French Central Agricultural Society, I took the liberty of writing to 
 M. Payen, who is one of the professors of chemistry in the Ecole 
 des Arts et Metiers, and who was lately in this country for the 
 purpose of inquiring into the state of our artificial manure manu- 
 factures. In reply to the letter which I wrote to him, that 
 gentleman says : " The exclusive use of a small quantity of 
 powdered manure to envelop seed, would evidently be both dan- 
 gerous and prejudicial to the true interests of farmer and land- 
 lord. I am authorised to add, that this is also the opinion of my 
 friend Boussingault, and of my other colleagues, the members of 
 the Central and National Society of Agriculture. Besides, the 
 experiments already made in France, and duly controlled by 
 Messrs. Moll and others, were not at all successful. The nu- 
 merous publications favourable to this ridiculous system of 
 cultivation without manure, do not deserve any confidence, 
 for they were paid for by the speculators, and inserted in our 
 gazettes as common advertisements, or publications of chimerical 
 results." 
 
 So much for the opinion of the French savans ; and I apprehend 
 that if it has not answered in France, it will not in England. If, 
 indeed, we could concentrate the virtue of twenty loads of farm- 
 yard dung into one pound, it would be an excellent thing for the 
 cause of agriculture. 
 
 But now for the analysis of this precious manure, for which 
 I paid at the rate of twenty shillings for four pounds and a half, 
 or at the moderate and unassuming price of 497, 15s. 6|d. 
 per ton ! The very first thing which presented itself, was fifty- 
 five to fifty-nine per cent, of carbonate of lime or common chalk ! 
 I will give you the full "analysis.
 
 50 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 Composition of a sample of Ftrtilising Powder, at the price of twenty shillings 
 f or four pounds and a half weight. 
 
 Silica 6-45 
 
 Moisture 4-91 
 
 Organic matter 25-79 
 
 Nitrogen _ . . . . 1-47 
 
 Carbonate of lime 55-59 
 
 Potash and soda 0-92 . 
 
 Sulphate of Lime 1-71 
 
 Iron not determined 
 
 Phosphate of lime 0-96 
 
 97'80 
 
 You must all consider the article too dear at the price. 
 
 Now, gentlemen, I have thus brought before you the nature 
 and extent of adulteration. My main object this evening has 
 been that the reality should go forth to the agricultural world. I 
 believe in fact, I know that there are parties in London who 
 are making several thousands a-year by adulterating manures. 
 The names of some of these men are scarcely known in the market, 
 but what they manufacture finds its way to the land. It is not such 
 gentlemen as yourselves who are chiefly exposed to this evil ; you 
 can protect yourselves ; but there are many of the poorer class of 
 farmers who are continually imposed upon without knowing it, 
 because they endeavour to buy two tons of guano for 13, instead 
 of being contented with one ton for that amount. I have placed 
 the matter before you, because I think it ought to go forth to the 
 agricultural world that farmers are being systematically and regu- 
 larly cheated; that they are imposed upon in this matter; that 
 they are constantly buying sand for guano, and oyster-shells for 
 bones ; that they are not merely cheated here and there, but that 
 parties make it their business to manufacture THE ARTICLE for no 
 other purpose than that of mixing it with manure. When all this 
 is known, the remedy will lie in your own hands. In the first 
 place, you should deal only with men who have a character to lose, 
 and who will not endanger their position by anything like de- 
 ception. In the second place, you should not neglect to avail
 
 ADULTERATION OF ARTIFICIAL MANURES. 
 
 51 
 
 yourselves of the security afforded by analysis. The facilities 
 for obtaining an analysis are much greater than they were, and it 
 is now very easy to get manures analysed at a trifling cost, and thus 
 to ascertain whether they are genuine or not. If agriculturalists 
 generally were vigorously to pursue this plan, I believe its necessary 
 effect would be to put a stop to adulteration, to drive the dishonest 
 dealers from the market, and to leave the manure trade in the 
 hands of honest and honourable men.
 
 /)2 LECTURES ON AORICUI.TURAT. CHK.M1STRY. 
 
 THE USE AND ABUSE OF LIME IN AGRICULTURE. 
 
 The use of lime in agriculture has been known from the 
 remotest ages; and the relation of the different kinds of lime.- 
 stone, and the composition of lime and its action in the soil, 
 are matters on which a book might be written with much greater 
 facility than a lecture can be delivered so as to embrace the 
 leading points. As, however, I have only a limited period for 
 introducing the subject, it must be my endeavour to place before 
 you its salient features as concisely as possible. 
 
 Now, it is desirable that I should in the first place describe 
 the principal limestones of this kingdom, and state in what direc- 
 tions they are distributed. We have in England three great 
 divisions of limestone rocks. The first formation, to the eastward, 
 is the chalk, which, beginning at Flamborougli Head, in Yorkshire, 
 proceeds south-westward to Dorsetshire, and, making a small bend, 
 performs the circuit of Kent, Sussex, Surrey, and Hampshire, 
 stretching from Beachy Head round to Folkestone and Dover. This 
 chalk also dips under the counties of Norfolk, Suffolk, and Essex, 
 and part of Kent; and wherever you bore downwards in those 
 counties which lie eastward of the chalk, you come to the chalk 
 again. You have then, from the Wash and extending right through 
 the fens of Cambridgeshire, a soft clay ; in fact, the very indentation 
 of the country in that direction is owing to the soft clay interven- 
 ing between the chalk and the oolite. Passing to the westward of 
 the fens, you have the oolite formation, which in its various charac- 
 ters extends from the Yorkshire coast near Scarborough, through 
 Rockingham Forest in Northamptonshire, to the Cotswold Hills, 
 and terminates in the sea at Bridport, in Dorsetshire. The oolites 
 contain three varieties of limestone. First, there is what is termed 
 the Portland oolite, found chiefly in the Isle of Portland, but of
 
 USE AND ABUSE OF 1,1 ME IN AGRICULTUKE. 53 
 
 which a little is found near Aylesbury. Then there is the middle 
 oolite ; and there is, moreover, the inferior oolite found largely 
 near Bridport. All these oolites furnish very good lime. After 
 these, there is the great development of mountain limestone 
 which is found so extensively in Northumberland and Durham, in 
 the Western parts of Yorkshire, in that part of Derbyshire which 
 is called "The Peak," and in other districts further to the south. 
 1 now come to the next division of limestone, that which is found 
 near Torquay arid in certain parts of Exmoor. This species of 
 lime is not very largely developed in this country ; but it exists 
 in two or three places, and, fortunately, just where it is most 
 wanted. We have also in the old red sandstone, or Devonian 
 system, the cornstones or nodular masses of limestone found 
 in Herefordshire, which make very good lime. We have, lower in 
 the series, the Silurian limestone, which is very much developed in 
 some parts of Wales, and is also found in large quantities near Dud- 
 ley ; and many persons present have, perhaps, seen the substance 
 which is called "Dudley limestone." The same formation is also 
 found in an adjoining county, Shropshire, where it is known under 
 the name of " Wenlock limestone." There is, also, the primitive 
 limestone found in some parts of Devon and Cornwall ; and, to com- 
 plete the catalogue, there is the shelly limestone of the Wealden 
 formation, between the chalk and the oolite, found at Bethersden, 
 Kent; Petworth, Sussex; and in the Isle of Purbeck, Dorset. 
 These, then, are the principal divisions of limestone ; and let me 
 observe that they are so distributed on the whole as to leave 
 very few parts of the country without the advantage of being 
 able to obtain a supply of this valuable article within the distance 
 of a dozen or twenty miles. 
 
 Having mentioned the distribution of the several formations, 
 I will next proceed to speak of their composition. Limestones 
 have been considered by some persons valuable in proportion 
 to their purity ; that is to say, in proportion to the absence 
 of anything else but carbonate of lime. You are aware, I presume, 
 that limestone is itself a carbonate of lime : in its pure form it 
 consists of twenty-two parts of carbonic acid and t.wenty-eight of 
 
 R
 
 54 I.KCTUHKB ON AGRICULTURAL CHKMI8TRY. 
 
 lime. When limestone is heated in the furnace, the carbonic 
 acid is driven oil', und pure lime left behind ; that is to say, it 
 would be pure if the limestone itself were pure. I was remarking 
 that it has been supposed that the purest limestone is the best. 
 1 shall now endeavour to prove to you that such is not the fact, 
 but that impure limestone that is to say, limestone containing 
 other substances besides carbonate of lime, is that which is best 
 adapted for agricultural purposes. There are, in fact, no lime- 
 stones found absolutely pure ; all contain a certain amount of 
 moisture, silica, iron, alumina, phosphate of lime, and even a 
 little sulphate of lirne. It is perfectly clear that limestones must 
 be the better for any phosphate of lime which they may contain. 
 As you are continually putting into the soil bones and other sub- 
 stances, because they contain phosphate of lime, it is evident that 
 those limestones which contain the largest proportion of phos- 
 phate of .lime are the most valuable, supposing the other consti- 
 tuents to be the same. We have analysed in our laboratory, some 
 hundreds of specimens of limestones : none were found free from 
 phosphate of lime, while probably the average proportion of it 
 was one per cent. Many limestones contain much more than one 
 per cent.: some contain as much as three or four; but, supposing 
 them to contain on the average one per cent, of phosphate of 
 lime, in that case ten tons of limestone, or its equivalent of 
 five or six tons of lime, put on the land, would furnish two 
 hundredweight of bone earth per acre, which I need not tell you 
 would be a considerable dressing, and would, for years afterwards, 
 prove advantageous to the soil. Well, then, many limestones also 
 contain silica in a soluble state, so that when put on the land it is 
 easily acted upon, and, in fact, disintegrated; and I think it very 
 probable that a limestone which contains a certain amount of such 
 a substance as silica, in a soluble condition, is preferable to what is 
 termed " pure limestone." Many also contain sulphate of lime or 
 gypsum, and even these are better adapted for general use than 
 such as approach nearer to a state of purity. 
 
 You will thus see that my opinion upon this part of the subject 
 is, that it is not the purest kinds of limestone which are calculated
 
 USE AND ABUSE OF LIME IN AGRICULTURE. 55 
 
 to confer the greatest benefit upon the farmer, but that those which 
 contain a certain amount of what are called impurities are the 
 best adapted to agriculture, because they convey to the soil other 
 constituents besides the calcareous matter. 
 
 It would be impossible for me, within the limits to which I 
 am restricted, to give you a distinct idea of all the different kjnds 
 of limestone. Indeed, I may remark, that the subject has not 
 been sufficiently investigated to enable me to enter into it as fully 
 as I could desire, and it would require much more time than I 
 have had at my disposal to make the necessary analyses. I had 
 intended and if my lecture had been postponed for a twelve- 
 month, I should probably have been in a position to bring under 
 your notice the results of the analysis of some of the chief lime- 
 stones of the kingdom ; but as the task of analysing would occupy 
 three or four months, you may easily conceive why I have not 
 been able to execute the whole. Speaking of the chalks generally, 
 however, I may say, in the first place, that we have three distinct 
 kinds, the upper and the lower, and the chalk marl, and that they 
 are distinguished by the fact of the lower chalk containing a 
 greater amount of silica and phosphate of lime, and being more 
 easily acted upon by frost, than the upper chalk. The chalk marl, 
 beneath the lower chalk, contains a greater amount of phosphate of 
 lime than either of the others, and wherever that is put on the 
 land, great benefit is derived from it. The next limestone which 
 I shall notice is the Weald limestone. It is of fresh-water forma- 
 tion that is to say, the shells which are found in it are fresh- 
 water shells ; and it is found at Bethersden, in Kent ; at Petworth, in 
 Sussex ; and in the isle of Purbeck, in Dorsetshire. It is the kind 
 of limestone which was used, during the reign of Henry I., in 
 laying the foundations of old London bridge. Besides carbonate 
 of lime, it contains about twenty per cent, of other matter ; and when 
 properly burnt into lime it proves very valuable to the land. The 
 next limestones are the oolites, well known at Pickering in York- 
 shire, at Northampton, at Higham Ferrers, and in various parts of 
 the country. These limestones contain, amidst a quantity of 
 other matter, three quarters per cent, of phosphate of lime. The
 
 56 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 next class are those of the lias, which are found in nodular 
 masses about Whitby and Lyme-Regis, and in other parts of the 
 country, and which are generally sent to London to make cement. 
 Below the lias limestones we have the mountain limestone, 
 which is well known in Derbyshire, particularly at Crich Cliff. 
 Many of you may have observed a number of limekilns, in pass- 
 ing by railway, just where you turn off for Matlock. The lime 
 of this district is very good, and is sent for miles to be used for 
 agricultural purposes, for which it is found extremely beneficial. 
 Next, there is the limestone which is found at Dudley, near 
 Birmingham. That formation has been pushed up by vol- 
 canic action ; having thus been obtruded into a spot which it 
 would not otherwise have occupied. Some parts of this limestone 
 are very pure, and other parts contain a large proportion of foreign 
 matters ; and I should certainly choose the latter for agricultural 
 purposes, but the iron-masters would of course prefer the purest. 
 We then have the limestones of Devonshire, which, generally 
 speaking, are tolerably pure. 
 
 I must next refer to the use of lime, and, in doing so, it will 
 be necessary for me to allude first to the practice of chalking or 
 marling. It has been found that the use of marly substances, 
 containing calcareous matter, is equivalent to the use of lime itself. 
 Jt does not seem to make much difference, generally, whether 
 you use calcareous matter merely in the state of carbonate of lime, 
 or use chalk disintegrated by frost, or whether you use quick- 
 lime itself. Although there has been a great deal of dispute on 
 the point, yet I do not think the experience of farmers has proved 
 that there is much difference in the result between the use of 
 quick-lime, or marls, or of soft limestone disintegrated by the 
 action of the air. A.nd, indeed, I do not see how there can be 
 much difference. If hard limestone is burnt into lime, when it has 
 absorbed moisture it becomes a very fine powder, a finer one than 
 could ever be produced by mechanical means. This powder, or 
 slaked lime, absorbs the carbonic acid of the atmosphere, and 
 again becomes the same carbonate of lime that it was before being 
 burnt. But its mechanical condition is now entirely changed.
 
 USE AND ABTTSE OF LIME IN AGRICULTUEE. 57 
 
 Instead of being a hard solid mass, it is a white friable powder. 
 Burning is chiefly useful in the case of hard solid limestones, 
 because by that means they are reduced to a powder, and in 
 this state they will readily act upon any substance in the soil. 
 Many persons have supposed that caustic lime exerts a great and 
 peculiar action in the soil, but to me this appears very doubtful. 
 The chief use of burning hard limestones is, in my opinion, that 
 it reduces them to that minute state of division in which they act 
 most readily on the soil. I am not at all singular in this opinion. 
 Nearly all chemists who have investigated the matter, have, I 
 believe, declared that lime in its caustic state, does not exert any 
 peculiar action', but that it is in the state of carbonate of lime 
 that its peculiar influence is witnessed. 
 
 We are then led to the conclusion that the same result is 
 obtained from marling, from the use of the easily disintegrated 
 chalk, and from the application of the harder limestone when 
 burnt. The effect differs only in proportion to the solubility 
 or non-solubility of the limestones. If these be very solid, or 
 if the marl containing limestone be not easily acted upon by 
 the air, you will not find those particular substances produce so 
 immediate an effect as others which contain the calcareous material 
 in a more soluble state, 1 that is to say, more minutely divided. 
 These marls, as I before intimated, will also vary in their 
 operation according to the quantity of phosphate of lime, silica, 
 alumina, and other substances of the same kind, contained in them. 
 Although carbonate of lime be the chief material, yet its action 
 will be modified by that of others with which it is connected. 
 
 You perceive, then, that limestones may be regarded in t.wo 
 distinct points of view, first with reference to the action of the cal- 
 careous matter considered as pure, and secondly with regard to the 
 action of the materials with which it is connected. 
 
 Having disposed of the latter part of my subject, so far at least 
 as my limits will permit, let me now proceed to speak of the 
 action of calcareous matter in the soil. 
 
 Lime, whether in the caustic state or in the state of car- 
 bonate of lime, has a distinct action on /the mineral ingredients in
 
 58 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 the soil. In our chemical analyses/if we want to liberate potash 
 and soda from an earth, we heat it red hot, in a crucible, 
 with lime; after which operation we can get all the potash 
 and soda from the soil by the action of water alone. Even if 
 we merely mix a quantity of soil with some lime and water, so as 
 to make a kind of milk of it, and leave it for five or six months; at 
 'the end of that time, on filtering the liquid, we shall find a con- 
 siderable amount of alkali dissolved out of the soil. In like man- 
 ner, when you put a quantity of lime on your land, and allow the 
 atmosphere to act upon it, the rains dissolve it; it becomes inter- 
 mixed, and, as it acts upon every portion of the soil with which it is 
 in contact, a considerable amount of alkali, which is necessary 
 for the growth of plants, is liberated for that purpose. 
 
 But lime acts powerfully not only on the mineral, but also on 
 the organic matters in the soil. And this is the great point which 
 I shall have to illustrate to-night, namely, that lime, when used 
 in the soil, acts materially on the organic matters therein con- 
 tained. All good soils contain a considerable amount of vegetable 
 matter, or have the power of absorbing from the air substances 
 adapted to the formation of vegetable matter. 
 
 When you have lime in the soil, whether it be put there in 
 the state of lime or in that of carbonate of lime, you have at 
 once a determinate action on the organic matters, and also a 
 greater power of absorption from the air. You have the decompo- 
 sition of roots and plants and other vegetable debris very much 
 augmented by the presence of the carbonate of lime. These sub- 
 stances are not able of themselves to decompose with sufficient 
 rapidity to furnish the greatest available amount of nutrition to the 
 growing crop. There can be no quick decomposition, for the sim- 
 ple reason that the substances which would be produced by decom- 
 position would find nothing with which 'they could unite; but in 
 carbonate of lime you have a substance with Which the different 
 vegetable acids formed in the various phases of decomposition can 
 unite at once. It is a fact well known to every gentleman here, 
 that it is on soils which contain a great amount of organic matter, 
 or which have not been under plough for a great many years, that
 
 USE AND ABUSE OF LIME IN AGRICULTURE. 59 
 
 lime produces the most marked effect. If you have worked your 
 land for many years as arable land ; if you have ploughed it, and 
 sown it, and reaped crops from it to such an extent as materially to 
 have affected the organic matter of the soil and the stores of am- 
 monia which it has absorbed from the air, lime will do little or no 
 good. But if the case be otherwise, you will find lime produce the 
 very best effects, because it immediately brings the stores of nitro- 
 gen and the organic materials in the soil into the best possible 
 state for plants to act upon them. I may mention also that 
 the action of lime is very effectual in peat soils and in soils which 
 contain sulphate of iron, where it is useful in correcting what is 
 called " sourness/' an evil which I need not tell you is to be 
 found in many districts. It can scarcely be necessary to mention, 
 that the soil, in order that lime may be useful, must have been pre- 
 viously drained ; without that it will be perfectly useless, drainage 
 being essential to eflable lime to percolate through the soil and per- 
 form its proper functions, 
 
 There is another action of lime in the soil to which it is 
 necessary for me to allude. You are well aware of the existence of 
 what are called nitre beds. You know that in the time of Charles I., 
 of Cromwell, and of Charles II., saltpetre was manufactured in this 
 country in a rather peculiar manner. Patents were granted to 
 persons to go and dig under old stables for the soil they could find 
 there, and to get the mortar from old buildings, etc. ; and out of 
 such materials was saltpetre produced. The process was very sim- 
 ple and very effective. During the whole course of the French 
 Revolution the saltpetre used by the French army was obtained in 
 a similar manner. A quantity of chalk or other calcareous matter 
 was laid up in heaps alternately with farm-yard manure. First, 
 there was a quantity of manure, then a layer of mortar or other 
 calcareous matter, then some more manure, then some more inor- 
 tar, ai^d so on. All this was watered with urine or with some 
 other liquid ; if urine could not be procured, pure water was 
 used. The whole was kept under cover in a tolerable state of 
 moisture, and turned every three or four months. After twelve 
 months no more urine was added, but water only. At the end of
 
 60 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 eighteen months the whole mass was put into a tank of water and 
 well stirred. After a time the water was pumped off; and in it 
 the whole of the ammonia and nitrogen of the manure and the 
 urine was found as nitrate of lime. All the nitrogen of the manure 
 was converted by slow oxydation into nitric acid, which united 
 with the calcareous matter to form a nitrate of lime. This solution 
 was subsequently mixed with wood ashes, which contain carbonate 
 of potash ; and by double decomposition there was formed car- 
 bonate of lime, which precipitated as a white powder, and nitrate 
 of potash (saltpetre), which was then crystallised. In this way was 
 made nearly the whole of the saltpetre used by Napoleon during 
 his protracted wars. 
 
 Gentlemen, what took place in the saltpetre beds in France is 
 taking place in your saltpetre beds your fields. If your fields are 
 properly drained, that they may absorb valuable materials from the 
 air, and if they contain the proper amount of calcareous matter, 
 there cannot be the slightest doubt that the same process will go 
 forward. Beyond this, it is an undoubted fact that more saltpetre 
 is derived from nitre beds than is equivalent to the nitrogen 
 contained in the manure and urine added to them ; that is to say, 
 that the air acts in some way upon these beds, and that there is an 
 absorption of nitrogen by them from the air. Under the influence 
 of the slow decomposition of the vegetable and animal matters, 
 nitrogen and ammonia are undoubtedly absorbed. If that be the 
 case if you have a proper amount of calcareous matter in your 
 soils, and a proper amount of organic matter, you will find them not 
 only producing nitre by their own decomposition, but likewise by 
 absorbing similar valuable matter from the air ; and this absorption 
 will take place in proportion to the exposure of the soil by means 
 of ploughing, and to the porosity produced by efficient draining, 
 harrowing, and other similar processes. 
 
 There are one or two points deserving of notice in reference to 
 the absorption of ammonia. I do not know whether you are aware 
 that all soils contain a considerable amount of ammonia or nitrogen, 
 in some form which is not yet perfectly recognised, and which does 
 not seem distinctly adapted for the use of plants. We have ascer-
 
 USE AND ABUSE OF LIME IN AGRICULTURE. Gl 
 
 tained in our laboratory, the amount of nitrogen contained in a 
 number of soils brought from various parts of the kingdom ; 
 some being of the richest descriptions, and others yielding 
 only a rental of from five to seven shillings per acre. We have 
 found a very considerable amount of nitrogen in the latter, evidently 
 not available for plants, but in such a state that it might be 
 rendered available. This matter will probably form the subject 
 of a communication to the Royal Agricultural Society, when we 
 have completed the investigation. For the present, I only mention 
 the fact that there is a very large amount of nitrogen in the soil, 
 which might be rendered useful; for, if you use calcareous matter, 
 you bring this material into distinct action, and make it capable of 
 being taken up and absorbed by the roots of plants. You will see 
 at once, by recalling what I have said, that if lime act distinctly 
 upon inorganic matter, and if it act upon inert organic matter 
 containing nitrogen, it is chiefly in the case of those soils 
 which contain organic matters intermixed, and which have not 
 been often ploughed or exposed to the air, that lime will be 
 of material use. 
 
 All experience bears out this view. If a man has worked 
 his land down to a low state, if he has been taking crop after 
 crop, without much manure, and then fancies that by liming 
 the land he can bring it back to its original state of fer- 
 tility, he will find himself mistaken. It is upon land newly 
 broken-up that lime tells best. In such a place as Exmoor, 
 indeed, where the land has not been turned up within the memory 
 of man, and where the soil contains only just enough lime for a 
 chemist to certify, you will find the use of any other manure of no 
 avail without lime. You may use guano, you may use bones, you 
 may use anything you please of that kind, but not a single crop 
 will you get, unless you also apply lime. In that part of the 
 country, you can see to an inch where lime has been used. If you 
 were to take a handful of slaked lime, and inscribe your name on 
 the soil, you would, even three or four years after, be able to trace 
 the exact spot where it was marked. I have myself observed on 
 that moor, that in certain parts where lime has been used, the 
 
 i
 
 62 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 turnips were splendid; hut the instant you passed the point up to 
 which the lime had heen applied, the crop entirely failed. 
 
 It is, then, my distinct opinion, that lime ought to be used on 
 such soils as contain a large amount of organic matter and, when 
 using it on arable lands, never to trust to it alone, but to use 
 other manures as well, though they ought not to be applied at the 
 same time as quick-lime. You all remember the old proverb 
 
 " The use of lime without manure 
 Will always make the farmer poor," 
 
 and that saying is perfectly true. 
 
 There is another action of lime which I wish to mention. You 
 know, of course, that most limestones contain sulphate of lime. 
 Rain brings from the air a quantity of carbonate of ammonia, 
 which being a volatile salt, easily evaporates again ; but if there be 
 any sulphate of lime in the soil, the ammonia does not evapo- 
 rate, because as soon as it comes in contact with the sulphate of 
 lime, the carbonate of ammonia becomes sulphate of ammonia. A 
 change takes place again after the superfluous moisture has 
 evaporated from the soil, for the sulphate of ammonia re-acts 
 on the carbonate of lime, arid carbonate of ammonia is again 
 given out. This is a very curious fact. I have here some chalk, 
 and if I add to it some sulphate of ammonia, I shall form a portion 
 of sulphate of lime ; carbonate of ammonia will then be liberated, 
 and may be easily detected by its odour. When soils are neither 
 too wet nor too dry, but only just moist, carbonate of ammonia is 
 liberated from the existing sulphate of ammonia. 
 
 There is another point which ought not to be omitted, as it is 
 of considerable practical importance, namely, that there may be 
 an almost entire absence of lime in soils resting upon limestone. 
 I have found soils resting upon limestone the Kentish Rag, 
 for example where the limestone has been within six inches 
 or a foot from the surface, and there was not a thousandth 
 part per cent, of lime in the soil itself. You know it is the 
 constant tendericy of lime to descend ; the consequence of this 
 is, that even soils which were formed by the disintegration of lime-
 
 USE AND ABSUE OF LIME IN AGRICULTURE. 63 
 
 stone itself, sometimes require liming as much as any others. I 
 know that in Dorsetshire, Wiltshire, and some parts of Hampshire, 
 farmers are absolutely chalking the Chalk Downs with manifest 
 advantage; and both in those counties and in Kent, lime and cal- 
 careous matters have, on my recommendation, been applied with 
 very great success upon soils resting on chalk or limestone. 
 
 There is yet another point which I wish to notice, namely, that 
 without the presence of carbonate of lime in the soil, you can 
 never have the full action of any description of manure. If there 
 be sulphate of ammonia in the soil, you cannot suppose that it 
 will be taken up into the plant as sulphate of ammonia ; it must be 
 decomposed before the ammonia can be absorbed. There is some- 
 thing required to unite with the sulphuric acid, and this is furnished 
 by the carbonate of lime. There must, therefore, be carbonate of 
 lime in the soil, and if you have that, you will have the sulphate 
 of ammonia giving its ammonia freely to the growing plants. You 
 could not usefully apply guano, or any other artificial manure, 
 without a proper amount of carbonate of lime in the soil. You 
 see, therefore, gentlemen, that it is necessary to have a certain 
 amount of lime in any soil whatever, if you wish to cultivate it to 
 the greatest advantage. 
 
 I will not trespass any further upon your time, except to 
 say, that the system of Tull which Mr. Smith has been lately 
 bringing forward is dependent upon the principle of the ex- 
 posure of soils to the air. You must in this case have a proper 
 amount of lime in the soil, or you can never have that proper 
 absorption of manuring properties from the air upon which the 
 system almost wholly depends. 
 
 The conclusions to be drawn from the few observations which 
 I have had the honour to offer to you, are, I think, these : that lime 
 can be used beneficially upon soils which have been little stirred, 
 little exposed to the air upon new soils, like those of Exmoor, 
 or upon those which contain, naturally or artificially, a certain 
 amount of organic matter but that if used without manure 
 upon arable soils, from which crop after crop has been taken, 
 without any manure being added, it will not restore fertility,
 
 04 J.KOTURKS ON AGRICULTURAL CTIEMISTKY. 
 
 and that those farmers who are in the habit of putting large 
 doses of it upon their land, trusting to that alone for good crops 
 for six or seven years after, abuse this most valuable sub- 
 stance.
 
 QUAMTIKS OF FOOD, AND FATTKNING OF STOCK. G") 
 
 THE QUALITIES OF DIFFEKENT KINDS OF FOOD, 
 AND THE BEST METHODS OF FATTENING STOCK. 
 
 IT will be necessary, in speaking of the best methods of fattening 
 stock, to take into consideration all the causes whereby gen- 
 tlemen who keep stock may sustain loss, or whence may arise 
 a deficiency in the year's accounts ; though I shall not be able 
 to enter at all into the question of the markets, or of the buying 
 and selling of animals. It will be my aim to bring under your 
 notice the principles on which the fattening of animals depends ; 
 and I shall endeavour to point out the cases in which loss may 
 arise, whether from the use of improper food, or from the want of 
 good ventilation. 
 
 I must speak first of the constitution of vegetables, and 
 of vegetable growth in general. Gentlemen, you all know that 
 the vegetables which you grow are not like those with which nature 
 clothes the fields. If you leave the bare surface of the land to the 
 action of the atmosphere, and to those causes which are constantly 
 operating, you find nature covering the fields with plants of her 
 own choosing ; and what you have to do, is to grow plants selected 
 from the whole mass of those which she has presented to you. 
 You single out certain plants for the purpose of obtaining the 
 largest quantity of those substances which are useful for animal 
 life. In doing this you reject the ordinary offers of nature, and 
 make use of her powers with the assistance of art. Of course, 
 you know very well that it is necessary that there should be a 
 total change in the land, when you thus proceed to cultivate plants
 
 66 LECTtTRKS ON AORICTTLTITRAI, CHEMISTRY. 
 
 differing from those which are produced by it in its natural state ; 
 and to secure this, you add manures which tend to raise the 
 produce to the highest amount. 
 
 The organic ingredients of plants, viz., oxygen, hydrogen, 
 nitrogen, and carbon, are generally derived by plants from the action 
 of the leaves on the air ; but when you manure your land with 
 common "manures, you always have the roots of the plants taking 
 up those substances from the soil as well. These are now absorbed 
 by the roots of the plants, though in the wild state of nature they 
 are generally taken up by the leaves only. Vegetables during 
 their growth are continually taking up carbon, hydrogen, nitro- 
 gen, and oxygen, retaining the three first and freely casting 
 out the last. In many plants, substances are often produced 
 containing not a particle of oxygen ; for example, otto of roses 
 and mamy of the essential oils. 
 
 Having mentioned the process which is constantly going on 
 in plants, I wish to show you that for the support of animal ex- 
 istence, the different vegetables produced may be divided into two 
 classes, having distinct properties. I have mentioned four mate- 
 rials carbon, hydrogen, nitrogen, and oxygen. In ail the sub- 
 stances which are adapted for food, oxygen is still present it has 
 not been totally cast out ; and we have the four elements which 
 I have mentioned both in animal and vegetable matters. 
 The common principles found in vegetables resolve themselves 
 into two classes, one destitute of nitrogen, the other containing 
 it. The former, to which I shall first refer, may be called the 
 non-nitrogenous elements of food, or the elements of respiration 
 and the producers of fat. Those bodies in vegetables which con- 
 tain no nitrogen are, fat of any kind whatever, oil, starch, gum, 
 mucilage, and various kinds of sugar. These bodies, I say, contain 
 no nitrogen : they are merely adapted for the production of fat, or 
 for the purposes of respiration. It is necessary to explain, however, 
 that these materials are of use in keeping up the animal heat. We 
 maintain the heat of our bodies by continually applying fuel that 
 is, food containing charcoal and hydrogen, and passing through 
 our system the air taken in by the lungs, which acts upon the
 
 QUALITIES OF FOOD, AND FATTENING OF STOCK. 67 
 
 combustible parts of our food precisely as it acts in lamps and gas 
 lights, where we burn carbonaceous substances by currents of air. 
 Thus in our own systems, and in those of all warm-blooded ani- 
 mals, there is a considerable portion of food consumed for the mere 
 purpose of keeping the temperature of the animal elevated abovei 
 that of the air in which it exists. The portions of the food of 
 animals which are especially employed for this purpose, are those 
 which I have mentioned. They contain no nitrogen whatever ; 
 they add nothing to the nutritive powers of the food ; they could not 
 enable any man to take a greater amount of exercise than usual ; 
 in no way do they tend to build up or support the animal organism. 
 They are used, in the first place, to supply the fuel for heating the 
 body. We take in by every inspiration a considerable amount of 
 oxygen, which, after acting upon the carbon and hydrogen of these 
 non-nitrogenous materials, passes out again in a consumed state. 
 Let me here mention the amount of carbon consumed each day by 
 various animals. Man consumes, on the average, from 12 to 14 oz., 
 and there is required for that consumption 37 oz. of oxygen ; the 
 horse consumes 97 oz., and requires 258 oz. of oxygen; and the 
 cow, consuming 70 oz. of carbon, demands 186 oz. of oxygen. You 
 clearly see, then, that our animal economy requires that a constant 
 supply of heat-producing materials should be brought into the 
 system, and that a constant supply of oxygen should be taken into 
 the lungs, in order that the body may be kept at a proper tem- 
 perature. 
 
 Now, after the temperature which is necessary for the animal eco- 
 nomy has been arrived at, you have left the excess of food beyond that 
 which the animal requires for heating purposes. What remains of 
 the oil, the starch, the gum, the mucilage, and the sugar, after the 
 necessary production of heat, is formed into fat. This excess of food 
 nature places upon the muscles in the form of fat, in order that if the 
 animal be subsequently, through any misfortune, deprived of food, 
 its days of feasting may in some measure minister to the necessities 
 of its days of fasting. Of course, under such an arrangement, 
 it is essential, for fattening purposes, that the animal should be 
 kept at a proper temperature, otherwise no fat can be formed from
 
 68 LECTUKES ON AGRICULTURAL CHEMISTRY. 
 
 these materials. This is one of the points which it is necessary 
 continually to keep in view ; for it will be found of material im- 
 portance in connection with practice, inasmuch as the variations 
 in the amount of food required by animals, will depend in a great 
 measure upon temperature. In proportion to the temperature 
 which an animal has to keep up, or rather in proportion to the 
 degree of cold to which it is exposed, will be the loss of the mate- 
 rials consumed in keeping up the animal heat. Therefore warmth 
 is always equivalent to food. The less animals are exposed to cold 
 and wet, the less will the elements of respiration be required to 
 produce the necessary degree of animal heat, and the more food 
 there will be left for the production of fat. Therefore, it is of 
 immense practical importance to the pocket that fattening animals 
 should be kept warm and well sheltered. I shall not now dwell 
 on this point, as I intend to advert to it again. You will find what 
 I have just said clearly illustrated by the different kinds of food 
 required by men in different parts of the world. Observe the 
 difference between the food required by the Hindoo in the tropics, 
 and that required by the Esquimaux in the arctic regions. The 
 Hindoo lives on rice, which contains a very small amount of 
 carbon and hydrogen, the producers of heat, as compared with the 
 fatty matters which are consumed by the Esquimaux. The Hindoo 
 is content with a small amount of rice and milk every day, whereas 
 the Esquimaux will eat two or three pounds of candles, and drink 
 a quart or two of train oil at once, without experiencing any ill 
 effects. An Esquimaux will even drink a quart of brandy without 
 suffering any injury ; and it is because the native of the northern 
 climate consumes such large quantities of fatty substances, that he 
 is able to go almost naked, notwithstanding the extreme rigour of 
 the climate. He consumes such a large amount of the heat- 
 producing elements, being in the habit of eating when he can get 
 it eight or ten pounds of whale blubber per diem, that a difference 
 of twenty or thirty degrees in the temperature of the atmosphere is 
 of little importance to him. On the other hand, you find that in 
 warmer climates, men not only require a less amount of heat- 
 producing materials, but if they take them in too large proper-
 
 QUALITIES OF FOOD, AND FATTENING OF STOCK. 69 
 
 tions into their system, they are thrown by them into bilious 
 diseases ;' while, if they attempt to subsist upon them in the hottest 
 weather, they soon cease to exist. 
 
 I shall now refer to the nitrogenous elements found in food. 
 These are the real elements of nutrition ; they are the producers of 
 flesh, and must be kept perfectly distinct in our minds from those 
 substances which produce only fat. Among the producers of flesh 
 we have vegetable fibrine, the gluten of wheat, albumen, and vege- 
 table caseine. If you take the turnip and press it, you will have 
 the fibrine or gluten in the pressed mass, while the juice will 
 contain the albumen and caseine. If you boil this juice, you will 
 have a coagulum of albumen precipitated, exactly as if you 
 had used the albumen or white of an egg. If you separate it by 
 filtration, and then add an acid to the filtered liquid, you will have 
 another precipitate, similar to that which goes down from milk, on 
 the addition of rennet or an acid, and similar in all its relations to 
 the curd of milk. This, which goes down last, is called caseine, 
 because it is precisely similar to the curd of cheese. That which 
 goes down by boiling, is called vegetable albumen, because it 
 resembles the albumen of an egg ; and that which remains insoluble 
 in the pressed mass, is called vegetable fibrine or gluten. These 
 three substances differ in the following manner : the fibrine 
 or gluten is insoluble in water ; the albumen is soluble in 
 water, but is coagulated and precipitated on boiling ; and the 
 caseine, or cheesy principle, is soluble in water, not precipitable by 
 boiling, but separable on the addition of an acid, such as rennet or 
 vinegar. The most important fact has yet to be mentioned, 
 namely, that these bodies are almost identical in composition, and 
 that they are also of the same composition as the flesh of animals in 
 general. Vegetables, then, clearly produce the staple of flesh, and 
 animals merely alter its mechanical structure and condition. 
 
 Now I beg you to observe the immense importance of these 
 bodies. Vegetable albumen is similar to, if not identical with, 
 animal albumen the white of an egg. Now see what a very 
 little thing will change the white and the yolk of an egg into 
 totally different substances. You have only to take the egg, with 
 
 K
 
 70 
 
 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 its principle of vitality, and to expose it to a certain temperature 
 for about three weeks, and you obtain bones, sinews, muscles, 
 claws, beak, eyes, feathers, nerves, lungs, liver, intestines, and the 
 various other parts of the animal economy. All these come from 
 these apparently simple substances, merely through the action of 
 heat and the principle of vitality. In like manner, when vegetable 
 fibrine and caseine are introduced into the stomach of an animal, and 
 are operated upon by the vital functions, they are dissolved and 
 distributed through the various parts to form the different bodily 
 organs required by the animal. I will here refer to some analyses, 
 made by various distinguished chemists, of the gluten, caseine, and 
 albumen obtained from vegetables and animals : 
 
 
 Carbon. 
 
 Hydrogen. 
 
 Oxvgen, &c. 
 
 Nitrogen. 
 
 
 Vegetable fibrine or 
 gluten,* 
 
 53-27 
 
 7-17 
 
 23-62 
 
 """"" 
 15-94 
 
 Dumas & Cahours. 
 
 " Albumen,* . 
 
 53-74 
 
 7-11 
 
 23-49 
 
 15-66 
 
 " 
 
 " Caseine,* 
 
 54-14 
 
 7-16 
 
 2303 
 
 15-67 
 
 Scherer. 
 
 Animal fibrine,* 
 
 53-83 
 
 7-02 
 
 23-57 
 
 15-58 
 
 Jones. 
 
 " Albumen, 
 
 53-37 
 
 7.10 
 
 23.76 
 
 15-77 
 
 Dumas & Cahours. 
 
 " Caseine, 
 
 53-50 
 
 7-05 
 
 23-68 
 
 15-77 
 
 
 
 Ox flesh, .. 
 
 54-18 
 
 7.93 
 
 22-18 
 
 15-71 
 
 Flavfair. 
 
 Ox blood, . . 
 
 54-35 
 
 7-50 
 
 22-39 
 
 15-76 
 
 u 
 
 There is the greatest similarity between these substances, 
 whether obtained from vegetables or from animals. Now it is 
 impossible to imagine that these materials, so nearly agreeing in 
 their composition with flesh, can be changed at all in their nature 
 when taken into the system; that they can when there receive 
 any addition either of carbon or of nitrogen. There can be no 
 doubt whatever that vegetables produce the flesh of animals ; 
 that the flesh of all animals has been prepared and made originally 
 by vegetables ; in other words, that animals dissolve already-pre- 
 pared matters, and, under the action of vitality, give them different 
 mechanical forms, and put them on the muscles of the body. We 
 
 These bodies contain about 1'5 per cent, of sulphur, and -4 of phosphorus, 
 the amounts of which are included in the oxygen column.
 
 QUALITIES OF FOOD, AND FATTENING OF STOCK. 71 
 
 
 
 have no reason to believe that the stomach of the animal acts upon 
 these matters in any other way than by solution, the vital force 
 afterwards putting each particle into its proper place in the system. 
 These nitrogenous matters are the real sources of nutrition, the 
 producers of flesh; their substances the nbrine,the albumen, and 
 the caseine are those from which we derive our muscles. If an 
 animal were fed upon the elements of respiration alone upon fat, 
 oil, gum, starch, or sugar it would be perfectly impossible for it to 
 grow, to work, or to live. If a labouring man were fed upon non- 
 nitrogenous food, he would soon die : no human being could exist 
 on such substances. Arrow-root, starch, and all similar materials, 
 of themselves are insufficient to sustain life ; they may do very 
 well to produce animal heat, but it would be perfectly impossible 
 to live on them alone ; they must be united with other materials, 
 containing nitrogen, which alone can repair the daily waste of the 
 muscles. Every motion which an animal makes with any muscle 
 causes a proportionate wasting of that muscle. At the time when 
 the motion takes place, the oxygen attacks the muscle and 
 dissolves a portion of it, equivalent to the amount of motion and 
 force produced. This is a method of heating independent. of the use 
 of non-nitrogenous or fatty and starchy foods. You know that 
 there are animals which live entirely on flesh. These require a large 
 amount of exercise ; the muscles of the body not being consumed, 
 they are obliged to keep in motion. Any of you who have seen 
 the carnivorous animals at the Zoological Gardens in their dens, 
 must have observed that they are almost incessantly in motion ; 
 and this motion arises from the fact that they consume a large 
 quantity of nitrogen, which can only be got rid of by means of 
 exercise. In all cases of motion, there is a consumption of the 
 muscles of the body, and the elements of nutrition are required to 
 replace what has been lost. The life of an American Indian 
 hunter is peculiarly suited to the food which he consumes. Such 
 men will sometimes go for days together without food, during 
 which time they will of course consume a large quantity of the 
 muscles of their body ; but when they have caught their prey they 
 devour large portions of it, and in a very little while, what was
 
 72 LliCTUIlES 0.\ AGRICVLTUBAI* CHKMISTRT. 
 
 
 
 the flesh of a buffalo, or some other wild animal, has become that 
 of a man. Thus the pursuit of the hunter is well adapted to his 
 food, and his food is equally adapted to his pursuit. I recollect a 
 case, related by Sir William Alexander, which tends to illustrate 
 this point. When he was travelling in Caffreland, there one day 
 came into the kraal a man who was almost starved, and whose body 
 was so emaciated with. want thnt it seemed as though he could 
 hardly survive another day. Sir William had often heard, that, in 
 that part of the world, men who had been a long time without food 
 would cat a shoep, if it were given to them, without the slightest 
 difficulty ; and he was told that if he gave this man a sheep he 
 would get well directly, although he seemed so near his end. 
 After some hesitation, Sir William gave him one of the Cape 
 sheep, which, though not quite so large as our Leicester.-*, weighed, 
 perhaps, from thirty to forty pounds. The man commenced eating 
 the animal, and did not leave off until he had consumed about 
 three-fourths of it. On the morning of the succeeding day, Sir 
 William found him strong and ,well ; so quickly had the muscular 
 materials of the sheep been laid upon the muscles of the man. 
 Many similar instances might be given of this apparently marvel- 
 lous effect apparently marvellous, I say, for it is not so when 
 considered in the proper light. In cases of this kind, the animal 
 economy has nothing to do but to dissolve the food which has 
 already been prepared for it, and to place it in its proper position 
 on the muscles, which are equally prepared to receive it. I may 
 here remark that, of all vegetables, beans, peas, and lentils contain 
 the greatest amount of flesh-producing principles. 
 
 Having thus mentioned these two kinds of food nitrogenous 
 and non- nitrogenous I desire now to point out what we may 
 learn by way of deduction from this, namely, that both rest and 
 warmth are necessary for the animal's due increase and proper 
 development. First, let me notice warmth, which is so important 
 that I need not apologise for introducing it a second time. As 
 animals must consume, in their bodies, a certain amount of the 
 elements of respiration in order to produce heat, and as they can 
 only lay up fat in proportion to what remains after the ncccssai \
 
 QUALITIES OF TOO!), AND FATTENING OF STOCK. 73 
 
 production of animal heat, it is evident that they should always 
 be so sheltered as to be enabled to use the elements of respiration 
 which are found in their food. It is also clear that if you take a 
 pound of starch, or oil, or gum, or sugar, and burn it for the pro- 
 duction of heat, it will produce far less heat than a pound of 
 coal will produce for the same purpose. Therefore, the time will 
 come, I think, when coal will assist the fattening of bullocks 
 in the winter : when, either by steam or by stoves, the animal Avill 
 be artificially warmed, and left in such a state as to require far less 
 food than he otherwise would for the production of internal heat. 
 I am decidedly of opinion, that any gentleman who is engaged 
 in the fattening of animals, would find it cheaper to purchase 
 coals than to consume an equivalent amount of the materials 1 
 have mentioned. Again, rest is necessary for the animal. As 
 every motion produces a corresponding destruction of the muscles 
 which make it, it is quite clear that the more animals move about 
 the more of the elements of nutrition will they require to supply what 
 has been wasted. Everybody knows the difference between a long- 
 legged Irish pig, which gallops about like a race-horse, and one of Mr. 
 Fisher Hobbs's little pigs^whose diminutive legs would scarcely suffice 
 to carry it through this room. The difference which exists as regards 
 fattening properties, of course arises from the different quantity of 
 exercise taken by the two classes of animals. If you want your 
 animals to be well fatted and fleshed, you ought not to allow them 
 much motion; you ought to keep them for the most part quiet, 
 and to let them have 110 more exercise than is absolutely requisite 
 for health. This is a case in which men of practical experience 
 cannot but agree with me. I should be very sorry indeed if you 
 allowed your animals no motion whatever ; because I think that, 
 considering the long period it takes to fatten them, some degree of 
 it is indispensable to health ; but depend upon it, in many cases 
 as, for instance, that of young calves destined for the butcher the 
 less motion there is the better. 
 
 There is another point of considerable importance. "We. know 
 that animals which are often asleep, gain more flesh than others 
 which are more wakeful. If you darken a place where animals
 
 74 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 are kept, you will find the animals much more disposed to be 
 drowsy, and consequently exhibiting a much greater tendency to 
 fatten, than will be the case if they are exposed to the light. 
 
 I shall now proceed to consider the necessity of adopting a 
 distinct treatment for fattening and for growing stock. The proper 
 modes of treatment to be pursued are quite different, and those 
 who make no distinction, will in the end find out their mistake ; 
 similarity of treatment cannot but fail in the result. The young 
 stock which you intend to grow must have very different treat- 
 ment from the stock you intend to fatten for the market. You 
 Avant the former to have a good constitution, and to increase their 
 muscles and general size, and these objects can only be secured by 
 means of a considerable amount of exercise. Every one knows that 
 the arm with which the blacksmith strikes the most becomes strong 
 by constant exercise. In like manner, young stock should have 
 frequent exercise in the open air, and take as much food as they 
 can eat of the proper kind, in order that they may fulfil the 
 purpose for which they were designed. There is one great mis- 
 take committed with regard to young animals. It is supposed 
 that before they have been weaned they can do with skimmed milk ; 
 in fact, that the materials which nature has provided for them can 
 be diminished in value without their experiencing any corresponding 
 injury. There can be no greater error than this. The milk itself 
 is well adapted for the purposes of nutrition. It contains caseine 
 for the production of flesh, phosphate of lime for the production of 
 bones, and sugar of milk and fatty matter for the production of 
 heat ; thus giving everything that good food can yield. But if you 
 take away the butter, and give the animal skimmed milk, you dimi- 
 nish that Avhich nature has provided for the purpose of maintaining 
 animal heat, and the animal may get cold, and be fevered. If, in 
 fact, you diminish what nature has provided, you are sure to sustain 
 corresponding loss. If you want to use the cream for butter, you 
 can add an infusion of linseed to the skimmed milk ; and when you 
 are beginning to wean the animal, you can by means of an infusion of 
 boiled beans, which contain caseine, and of linseed, which contains 
 gum, with a little treacle or sugar, make a powerful milk ; for in
 
 QUALITIES OF FOOD, AND FATTENING OF STOCK. 75 
 
 these substances you have all that was to be found in the original 
 milk. Great care should be taken in the rearing of young stock to 
 give them the elements of nutrition. You must not confine them 
 to oily and starchy compounds ; for these will not serve the purpose. 
 Even in the case of the human subject, parents often fall into a 
 very great error by feeding their children upon arrow-root alone, or 
 upon other similar substances. They suppose that arrow-root con- 
 tains some flesh-producing principle, when in point of fact it 
 contains nothing of the kind, but is merely starch, and consists of 
 carbon , oxygen,, and hydrogen. It may be very well for persons who 
 are unwell, and whose stomachs are in a delicate state, to take the 
 lightest kind of food ; but for children, or those who are growing, it 
 is the worst kind of nutriment that can be given. On the other hand, 
 those kinds of food which contain the greatest proportion of nitrogen 
 are the most useful for nutrition. There is a food recently intro- 
 duced by Mr. Bullock, of Conduit Street, which consists of the 
 flour of wheat kneaded with water till nearly all the starch has 
 been got from it. This contains six times the amount of nutriment 
 that is contained in ordinary flour, and it is one of the best kinds of 
 food that has ever been devised. I repeat that young and growing 
 stock ought to take exercise ; it is absolutely necessary for them, 
 in order that they may have a good constitution, and that the 
 muscles, well developed by exercise in youth, may have proper 
 capacity for increase in age. 
 
 I shall next refer to the cooking of food, and to the difference 
 between barley and malt. On this subject I may observe, that 
 there is a great deal of misunderstanding as to what cooking can 
 effect. If nutritive and useful materials exist in a certain kind of 
 food, cooking can only be useful by aiding their solubility. It will 
 make them more soluble, and on that account a less amount of 
 food probably will pass through the system undigested. I do not 
 suppose that if we \vere to steam sawdust for any length of time, 
 we should convert it into a good food for animals. Those parts of 
 the substance which are indissoluble, and which consist of woody 
 matter, still remain ; but the other parts, such as starch, or gum, 
 or oil, or fat, are made soluble in water, and consequently will
 
 /(> LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 be more easily assimilated. The great point to be kept in view, 
 is the making the food more soluble, so that it will be more 
 readily acted upon in the animal. But there are two sides to this 
 question ; and it is very important that such things should not be 
 canned too far. The functions of digestion are, I need scarcely 
 say, very important ; nor are they so simple as some are apt to 
 suppose. There are more processes than one going on ; and there 
 are many things to be considered in relation to them. If the re-' 
 quisite amount of saliva be not swallowed, this may cause a great 
 defect in an important element of health ; and if animals swallow 
 their food too quickly, probably they will not have sufficient saliva 
 for digestion. It is necessary to avoid, I say, going to extremes in 
 these matters : it is quite possible to prepare food so that it will be 
 too easily swallowed. On this subject I would suggest to gentlemen 
 who are engaged in farming, to observe whether my remarks arc 
 not borne out by their own experience. 
 
 On the subject of the difference between barley and malt, there 
 have been a very great number of discussions. We have had 
 the government giving results, which are corroborated, to a 
 certain extent, by the experiments of Mr. Lawes ; but, not- 
 withstanding this, I consider the question as yet by no means per- 
 fectly settled : I think it necessary that some additional expe- 
 riments should be made. As far as I understand the experiments 
 of Mr. Lawes, the plan on which he proceeded was that of giving 
 to animals continuously a certain quantity of malt ; whereas in my 
 judgment malt should be given, not continuously or exclusively, 
 but as an occasional stimulant, and along with other food. There 
 is a decided loss of vegetable matter in the process of malting 
 or germinating. It must never be forgotten that a quarter 
 of barley does in fact contain more nutritive matter than an 
 equivalent quantity of barley converted into malt; and it is pos- 
 sible that by merely steeping barley, you would obtain all the 
 good that you Avould secure by drying and making malt. I make 
 these remarks, because I think it very desirable that some other 
 experiments should be performed, for the purpose of clearing up 
 the question, and deciding whether malt used in smaller quan-
 
 QUALITIES OF FOOD, AND FATTENING OF STOCK. 77 
 
 titles than by Mr. Lawes and Dr. Thompson, may not be a useful 
 adjunct in the feeding of animals, and cause them to eat and fatten 
 more than they otherwise would. 
 
 Another point which I think it necessary to mention is the use 
 of salt. The effect of salt, as taken into the system, is to enable 
 the animal to form bile. Bile is a compound of a sort of carbona- 
 ceous resinous matter and soda. Soda, as you all know, is formed 
 from common salt. Without the presence of common salt in food, 
 no bile can be formed ; its presence is essential to the healthy action 
 of the animal frame. But mind, any means which produces an excess 
 of bile merely robs the animal of a portion of its food, and prevents 
 the formation of a quantity of fat ; because the bile is formed from 
 fat, oil, gum, sugar, and so on, and really represents and embodies 
 the carbonaceous materials destined for immediate consumption. 
 The more bile you produce the less fat you produce ; and the more 
 salt you give to animals the more bile you allow them to form. In 
 these remarks I allude especially to fattening, not to growing stock. 
 To the latter, salt may often be an advantage ; but though fatten- 
 ing animals may like salt, I think it injudicious to give them the 
 free use of it. It is quite evident that, in summer especially, ani- 
 mals are very fond of salt; but if you want them to grow fat with 
 the least expenditure of food, I think you ought to give them salt 
 only in very small quantities. And then you are also to remem- 
 ber that all vegetables contain salt. A bullock will eat daily in 
 its food five ounces of salt, which is contained in the ordinary 
 saline materials of the food itself. If I were inclined to give ani- 
 mals salt at all, I think I should do so by the indirect mode of 
 throwing it upon the land, and leaving the animals to take it up in 
 their food. 
 
 Another point which I wish to mention, is the selection of 
 stock. Of course I do not mean to dictate to practical men how 
 they should choose their animals ; but I may, perhaps, be per- 
 mitted to remark, that the animals which are likely to prove the 
 best for the market are those which have the smallest bones, liver, 
 lungs, and intestines. This leads us to the consideration of the 
 constitution and fattening properties of different animals. We all 
 
 L
 
 78 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 know that when animals are fattening, and have gone on fattening 
 for some time, they require a much smaller quantity of food than 
 they did at the commencement of the process. Of course the more 
 oxygen is taken into the system by the lungs, the greater is the 
 consumption of the elements of respiration, and the less the pro- 
 duction of fat. Animals with small lungs, livers, and intestines, 
 will consume the least amount of food, and have the greatest ten- 
 dency to fatten. They will consume less of the ordinary kinds 
 of food ; they will also produce less bile, and consequently 
 a greater amount of fat with a less consumption of food. Now, 
 what is the case with regard to the horse ? It is entirely different 
 from that of which I have just been speaking. In the case 
 of the horse, you want the largest lungs ; because what is 
 chiefly required is wind. You do not want horses to fatten, but 
 you want them to have large lungs, so as to be able to keep up 
 their pace ; and therefore in the treatment of horses, you should 
 pursue a totally different system from that which you adopt 
 with regard to fattening stock. And here I would observe, that 
 stock, fattened in the manner I have described, are evidently more 
 delicate and more liable to disease than animals which have from 
 infancy been exposed to the ordinary varying influence of climate. 
 Therefore, it is important to consider whether it be not possible 
 that we carry our breeding too far, and sustain loss from having 
 animals which are too delicate. 
 
 Another point to which I would advert is ventilation, the 
 want of which is, I believe, a fertile source of loss to many 
 gentlemen who are engaged in farming. I have, in various 
 parts of the country, "been into stables and sheds, which are 
 not only unfit for any human being, but for any animal what- 
 ever to live in, and where animals have been obliged to breathe, 
 over and over again, materials absolutely destructive to life 
 I have thought that a few experiments on this subject would 
 more clearly show the necessity for attending closely to the matter 
 than anything which I could say, and these experiments I will now 
 proceed to exhibit, in the hope that they will answer the design. 
 The noxious gas given out of the lungs, partakes of the character
 
 QUALITIES OJf FOOD, AND FATTENING OF STOCK. 79 
 
 of the smoke which escapes from chimneys. We all know that if 
 persons shut themselves up in a room, close the door, and then 
 burn pans of charcoal, they must speedily die ; they will, in 
 fact, be killed by the fumes of charcoal which come out of the 
 pans. In like manner, all animals may be killed by the fumes 
 given out from the lungs ; and when stables and other places are 
 not sufficiently ventilated, this effect, gradually at least, often takes 
 place. The same noxious gas arises from all burning bodies which 
 contain carbon. It is one of the properties of this gas to form a 
 white precipitate with lime or baryta water. On holding a common 
 ale-glass over the flame of a candle, or burning paper, closing the 
 mouth of it with the hand, then pouring a small quantity of lime- 
 water into the glass, and shaking it, a white precipitate will be 
 formed. [Experiment performed.] To illustrate more clearly and 
 easily the properties of this gas, called by chemists carbonic acid gas, 
 I will procure some from common chalk, which is carbonate of lime. 
 On adding a little common muriatic acid and water to the chalk 
 in this jar, the stronger acid will liberate a large quantity of this gas, 
 and we can then examine its properties. [The gas prepared.] 
 This gas is much heavier than the air, which it has no doubt 
 completely driven out of the glass : this we shall discover by in- 
 serting a lighted taper, which will be immediately extinguished. 
 On pouring a little of this gas into the lime-water in this glass, 
 you perceive the same white precipitate as from the gas of burning 
 bodies ; and, though you cannot see the gas because of its trans- 
 parency, yet if I pour from this apparently empty jar the contained 
 gas over the flame of a candle, it will be put out. Whatever 
 extinguishes flame would also extinguish animal life : the one 
 effect is just as certain as the other. It is the gas thus produced 
 which is called the after-gas, or choke-damp, of the miner, and 
 which destroys the lives of so many persons in pits whenever an 
 explosion takes place the after-gas destroying, in fact, far more 
 lives than the explosion, itself those who were not killed by the 
 one being destroyed by the other. I will now show you that the 
 gas of my lungs will give precisely the same precipitate as this 
 noxious gas from other sources. It may be as well to mention here,
 
 80 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 that the quantity of this poisonous carbonic acid given out 
 daily by man is 27 cubic feet by the cow 137 cubic feet; 
 these numbers also representing tjie amount of oxygen united 
 with charcoal in the system to produce the necessary animal 
 heat. Now, I would observe, that there is a double deterioration 
 going on where an insufficient quantity of air is breathed by a 
 number of animals : first, the oxygen, without whose presence we 
 cannot live, is absorbed ; secondly, it is replaced by carbonic acid, 
 which is a deadly poison. To what an extent, then, may the air 
 be deteriorated by inattention to this subject ! I would here refer 
 to what the Almighty has done in nature, as it tends to show the 
 importance of the whole question. God has so diluted this sub- 
 stance, that 10,000 feet of common air contain only feet of car- 
 bonic acid. It has been ascertained that five per cent, of it in the 
 air acts as a poison to animals. Therefore, in order to know how 
 much air would be vitiated in one day by a horse, you have only 
 to multiply 190 cubic feet by 20, and the product will be 3,800 
 
 9 
 
 cubic feet of air, which would be rendered perfectly poisonous by 
 one horse in twenty-four hours, and half of that amount, 1,900 
 cubic feet, in the course of twelve hours. It is, therefore, quite 
 easy to understand how poisonous may be the air of stables. Air, 
 with four per cent., three per cent., two per cent., or even one per 
 cent, of carbonic acid, must have poisonous properties in a greater 
 or lesser degree. In relation to economy, and to the state of your 
 balance-sheets at the end of the year, nothing can be more im- 
 portant than the subject of ventilation. Without attention to this, 
 you may give animals the best kinds of food, and all may be turned 
 to poison : you will be only throwing away your money. 
 
 Now, as I said before, all that it is in my power to do is to 
 bring before you principles, leaving you to test them yourselves 
 by practice. There are so many important points embraced in 
 the subject, that it would have been impossible for me to notice 
 them all ; but sufficient have, I trust, been introduced to elicit 
 inquiry and discussion. 
 
 There is one other point which I must notice before I conclude, 
 namely, the necessity of mixing different kinds of food together,
 
 QUALITIES OF FOOD, AND FATTENING OF STOCK. 8] 
 
 with a view to the assisting proper and healthy digestion. You 
 should take care to have a proper mixture of nitrogenous and ndn- 
 nitrogenous food. The carnivorous animals, as you well know, 
 live upon flesh alone ; and between them and herbivorous animals 
 there is a very great difference, as regards the changes to be made 
 in food. The proper mixture can, in fact, only be determined by 
 experience, but great care should be taken not to give too much 
 food, whether of one kind or of another. It is quite possible to 
 injure an animal by the amount of one particular kind of food 
 which you give to it. It is a question to what extent even oilcake 
 should be used in fattening animals. I believe that, in a great 
 number of cases, it is given to too large an extent. Persons some- 
 times give animals large quantities of this food under the supposi- 
 tion that, if it do not benefit the animal itself, yet by passing 
 through it it will secure benefit in the shape of manure. All I 
 will say on that subject is, that a ton of guano is equal, in manuring 
 powers, to two tons and a half of oilcake ; and that, therefore, 
 unless the latter benefit the farmer by being converted into beef or 
 mutton, it will be a most expensive medium of manuring. When 
 you know that there is such a thing as food passing through the 
 animal system without being digested when you know that starch 
 granules may pass through the system without being acted upon 
 by the stomach you cannot but feel that if you give animals more 
 oilcake than is adapted for them, the substance may pass through 
 'the body without being acted upon, and the loss will be in propor- 
 tion. A short time since, I wrote to my friend Mr. Mechi to 
 secure his assistance in illustrating my lecture this evening, but I 
 am sorry to say that I have been disappointed. The question 
 which I wished to have solved is this : How much oilcake can a 
 good fattening bullock eat per day, without any passing through 
 the system unacted upon ? I wished a bullock to be fed three 
 days, with say three pounds of cake per day, at the end of which 
 time I wished a sample of its dung to be bottled up for analysis. 
 The next three days the animal should have six pounds per day, 
 and then nine pounds, and so on. The various samples of dung 
 should then be analysed the quantity of oil and the amount of
 
 82 
 
 LECTURES ON AORICULTUKAL CHEMISTRY. 
 
 nitrogen carefully determined ; and then we should have the means 
 of knowing how much went through the animal untouched and 
 unacted upon. 
 
 I will not trespass further on your attention. I will only say, 
 in conclusion, that I think, as agriculturists, you ought to cherish 
 science. True science never puts itself out of its place ; and 
 I think true practice should never do so either. What we want 
 is a union of the two. It would he better if practice and 
 science were united in the same person ; hut so long as that is not 
 the case, and so long as the rising generation are too young to 
 apply what they are learning, we must look to a union of scientific 
 men with practical men. The really scientific man who knows 
 the requirements of farming, will never for a moment conceive that 
 he can supersede the practical experience of ages by any theories 
 of his own; and, on the other hand, the practical man should 
 not be too ready to condemn the scientific man, because he is 
 unable to explain every circumstance and every fact in nature.
 
 PROPERTIES OF PERUVIAN GUANO. 83 
 
 ON PERUVIAN GUANO: 
 
 ITS HISTORY, COMPOSITION, FERTILISING QUALITIES, AND MODE 
 OF APPLICATION TO THE SOIL. 
 
 IN reviewing the history and condition of agriculture for the. last 
 twenty years, it is impossible to avoid being struck by the remark- 
 able progress, scientific and practical, which the latter half of that 
 period has witnessed. 
 
 The genius of our mechanics has been shown by the invention 
 of a wonderful variety of new and interesting instruments adapted 
 for an improved culture of the soil. The steam engine also, hith- 
 erto almost exclusively used by the manufacturer, now lends its 
 powerful aid to the farmer. The art of the drainer has brought 
 into successful cultivation thousands of acres of wet and almost 
 worthless soil ; and a vast breadth of land, previously only partially 
 drained, has been permanently and effectually ameliorated. 
 
 But perhaps the most remarkable feature of the whole is the 
 introduction of the so-called "ARTIFICIAL MANURES," and the 
 vast advantage derived by agriculture therefrom. 
 
 Previous to 1840, with the exception of local manufacturing 
 refuse, the only artificial manures were bones, salt, and gypsum. 
 
 The introduction of bones, many years back, was of great 
 importance to the farmer, and enabled him to grow, with compara- 
 tive ease, that mainstay of the four course shift the turnip. 
 
 To the impoverished soils of Cheshire,, and other cheese ex- 
 porting counties, bones were also an immense boon, and were duly 
 appreciated. 
 
 The publication of the first edition of " Liebig's Agricultural 
 Chemistry," in 1840, forms an important era in agriculture. Since
 
 84 LECTURES ON AGRICULTURAL CHEMISTRY 
 
 that period, the chemist 1ms more generally directed his experiments 
 to the investigation of the true principles of fertility, the merchant 
 has sought for foreign sources-of valuable manure, and the farmer 
 has reaped the benefits of the labours of them both. 
 
 That an increase of solubility in bones and other phosphates 
 would be attended by an increased productive power in the crop, 
 was the idea of Liebig. This great chemist, in 1840, recommended, 
 in lieu of bones, the use of the substance long well known to che- 
 mists as the acid or superphosphate of lime, which is producible 
 from bones and 6ther phosphates by the action of sulphuric acid. 
 Practice has since shown the great advantage of Liebig's sugges- 
 tion. 
 
 The introduction of the dung of birds and other animals, under 
 the name of " GUANO ;" and the, discovery, in Suffolk and other 
 counties, of immense quantities of fossil bones, and other animal 
 remains, known as " COPROLITES," have followed quickly upon 
 each other ; and there can be no doubt that, by their means, an 
 entire revolution will be made in the practice of agriculture. 
 
 The concentrated character of most of the genuine artificial 
 manures, particularly adapts them for us'e in the mountainous and 
 hilly districts of our country, where the carriage of ordinary manure 
 is both difficult and expensive. One wagon may now easily carry 
 enough manure for fifteen or twenty acres of turnips. Formerly 
 fifteen or twenty loads were required for a single acre. 
 
 Of all the artificial manures, Peruvian guano is perhaps not 
 only the most concentrated, but is, from its composition, adapted 
 to the greatest variety of crops. The chief mineral constituents 
 of plants lime, magnesia, potash, soda, chlorine, sulphuric acid, 
 and phosphoric acid (the latter the most important), are found in 
 guano. Nitrogen, the most valuable constituent of manures, is 
 found in Peruvian guano in great abundance, and in a condition 
 adapted for vegetation. 
 
 The use of this manure in Peru is of very ancient date; and 
 for its preservation, and that of the birds by which it was deposited, 
 the most stringest precautions were made use of by the native 
 Incus and their Spanish successors. At one period the punishment
 
 PROPERTIES OF PERUVIAN GT7ANO. 85 
 
 of death was inflicted upon any one disturbing the birds in the 
 breeding season. 
 
 ,The Chincha islands, which contain the great guano deposits, 
 are situated in the Pacific Ocean, off the coast of Peru, at the dis- 
 tance of about twelve miles. 
 
 They lie between lat. 13 deg. and 14 deg. S. ; a zone within 
 which no rain falls, where the air is dry, arid the sun shines with 
 vehement power. The waters of the surrounding ocean contain 
 innumerable shoals of fish ; and myriads of birds, after daily satis- 
 fying their voracious appetites upon the finny tenants of the deep, 
 have for ages made the islands their nightly abode, and the recep- 
 tacle of their faecal offerings. From the arid nature of the climate, 
 the excess of humidity has speedily evaporated from their ordure, 
 decomposition has been arrested, and by gradual accumulation from 
 time immemorial, these extraordinary deposits have attained the 
 depth, in many parts, of one hundred feet. 
 
 The guano, as found on the islands, is subject to slight varia- 
 tions in composition. Towards the S.W., the deposits are more 
 exposed to the action of the spray of the sea, brought by the pre- 
 vailing winds. Some of these guanos have lost by this means a 
 large amount of ammonia, and are not brought to this country ; in 
 others, the deterioration is trifling, and many are -simply disco- 
 loured, without having suffered any other change, and are equal in 
 value to paler samples. * 
 
 That the excrementitious matter of birds, fed upon an unlimited 
 supply of animal food, would of itself have powerful fertilising pro- 
 perties, might almost have been taken for granted, without either 
 'calling for the opinion of the chemist, or the experimental proofs 
 of the farmer. But both chemist and farmer alike bear testimony 
 to the high position assumed by guano in the catalogue of manures : 
 the former, by comparing its composition with that of other 
 known fertilising bodies ; the latter, by actual trial in the field. 
 
 It has long been a growing opinion with, chemists, that ammo- 
 
 * Messrs. Ant. Gibbs and Sons, as agents in this country of the Peruvian 
 Government, are the sole channel through which the Peruvian guano finds its 
 way into commerce.
 
 LECTURER OK AGRICULTURAL CHEMISTKY. 
 
 nia and phosphate of lime are the two most important and valuable 
 elements of plants, and,, consequently, of any manure which is to 
 aid in the development of vegetable life. This opinion has been 
 founded, in the first plr.ce, upon numerous analyses of various 
 manures; and, secondly, upon practical experiment. 
 
 It has been proved, for example, that, in two samples of farm- 
 yard dung, the one which gives the best crop in practice, contains 
 on analysis the largest amount of ammonia and bone earth. It is 
 a "well known fact, that the seeds of a vegetable contain more 
 nitrogen (ammonia) and phosphate of lime than any other portion 
 of the plant; and it is also well known that the dung of animals 
 fed upon seeds is more valuable than that of others fed only upon 
 hay, straw, or roots. Hence the practice of feeding animals upon 
 oilcake (crushed linseed), to obtain a better quality of dung. That 
 ammonia and bone dust are the most valuable of manuring princi- 
 ples, may also be inferred from the fact, that the artificial manures 
 most used by the fanner are those which contain the greatest quan- 
 tities of these elements, and that these manures are precisely those 
 which fetch the highest price in the market. 
 
 A comparison, therefore, of the composition of various excre- 
 ments of animals, and of farm-yard dung, with that of an average 
 sample of guano, \viil afford a very fair means of ascertaining their 
 relative fertilising powers. 
 
 The following table contains analyses of various manures, made 
 by Boussingault, and other well-known chemists, and also the 
 analysis of an ordinary sample of Peruvian Guano. 
 
 ANALYSES OF FARM-YARD DUNG, &c. 
 
 
 Fard-yard 
 Dung. 
 
 Hone 
 Dung. 
 
 Cow 
 Dung. 
 
 Pig Dung. 
 
 l-a 
 
 SHs 
 
 1ll 
 
 5 g 
 
 Peruvian 
 Guano.* 
 
 * 
 
 Moisture 
 
 79.30 
 
 76.17 
 
 86.44 
 
 82.00 
 
 94.24 
 
 18 35 
 
 Organic matter ... 
 Inorganic matter . 
 
 14.03 
 6.67 
 
 19.70 
 4.13 
 
 11.20 
 2.36 
 
 14.29 
 3.71 
 
 1.1-2 
 1.04 
 
 51.25 
 30.40 
 
 Nitrogen (equal to) 
 Ammonia 
 
 100.00 
 0.41 
 
 04-) 
 
 100.00 
 0.65 
 0.78 
 
 100.00 
 0.36 
 0.43 
 
 100.00 
 0.61 
 0.74 
 
 100.00 
 
 0.94 
 1 1 i 
 
 100.00 
 13.88 
 16.85 
 
 
 
 
 
 
 
 
 These analyses were made in the laboratories of the College.
 
 PROPERTIES OF PERUVIAN GUANO. 87 
 
 Boussingault, Payen, and many others of our first practical 
 Agricultural Chemists, have come to the conclusion that the value 
 of different manures varies nearly in proportion to the amount of 
 nitrogen they contain. There may be cases to which this rule is 
 not exactly applicable; but in many natural manures, an increase of 
 nitrogen is accompanied by an increase in the phosphate of lime, 
 and every other valuable manuring element. In the above table^ 
 for instance, the 13.88 of nitrogen in the guano, is accompanied by 
 30.40 parts of inorganic; matter, of which 23.60 parts (or more than 
 two-thirds), is phosphate of lime. 
 
 If we take the per centage of nitrogen, then, as a correct indica- 
 tion of manuring value, we shall find that one ton of ordinary 
 Peruvian guano, is equal to 
 
 33| tons of farm-yard dung. 
 
 21 tons of horse dung. 
 
 38J tons of cow dung. 
 
 22f tons of pig dung, and 
 
 14| tons of mixed human excrements. 
 
 Let those who farm in hilly countries, and other places where 
 carriage is expensive, ponder well the above facts. 
 
 Though a good farmer will produce as much manure as he con- 
 veniently can, yet even farm-yard dung may be bought too dear ; 
 and it is certain that on numbers of farms the cartage of dung is so 
 expensive an item of'management, that the introduction of guano 
 for those parts at the greatest distance from the homestead, would 
 be productive of the same fertility, at a considerable saving of 
 expense. 
 
 A question now arises whether the fertilising properties of guano 
 will be expended in the first year of its application, or whether its 
 operations will be discernible in after periods. If we examine the 
 chemical constitution of guano, we shall find it to occupy the medium 
 position between those manures which, being altogether soluble, are 
 somewhat transient in their effects, and that other class, which, like 
 bones, are only slowly decomposed in the land, and yield their 
 manuring principles with a certain degree of difficulty. Guano, 
 in fact, possesses every advantage of both. From. analyses which
 
 88 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 have been made, it is found that about one half of the fertilising 
 properties of guano are soluble in water, and therefore adapted 
 for the instant nourishment of plants. The other half continues 
 long in the soil, eliminating nourishment for vegetables by slow 
 decomposition. The soluble phosphoric acid, which it has been 
 found necessary to produce artificially from bones by sulphuric 
 acid, exists naturally in guano. If a guano contain in the whole 
 say twelve per cent, of phosphoric acid, and seventeen per cent, of 
 ammonia, we shall find that water will dissolve about six per cent, 
 of phosphoric acid, equal to about thirteen per cent, of phosphate 
 of lime in a soluble state, and at least eight per cent, of the am- 
 monia. Guano is thus adapted, by its insoluble matter, for the 
 lighter soils, where infiltration might too rapidly carry away the 
 soluble matter ; and by jts soluble constituents it is fitted for 
 heavier lands, where decomposition being slower, a supply of 
 soluble manure is required at once. 
 
 The fact of so considerable a portion of soluble phosphates 
 existing in guano is of great importance, as we have in a natural 
 form that which we are obliged to produce artificially in other 
 manures, by the action of acids upon bones and other insoluble 
 phosphates. 
 
 In fact, good guano partakes of the nature of superphosphate 
 of lime, as it contains both soluble and insoluble phosphates. 
 These together generally amount to the average quantity found in 
 commercial superphosphate of lime. 
 
 At the present price of Peruvian guano, it is more than ques- 
 tionable whether the ordinary plan of increasing the available 
 manure on a farm by the importation of oilcake and the feeding 
 of stock is at all economical. If the oilcake owes its fertilising 
 properties to the nitrogen and phosphate of lime it contains, it is 
 certain, from the analyses of various chemists, that Peruvian guano 
 is a much cheaper source of these substances. In a lecture lately 
 delivered by the author before the farmers of Dorchester, this 
 subject was alluded to as follows :
 
 PROPERTIES OF PERUVIAN GUANO. 
 
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 90 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 These observations are amply supported by the opinion of the 
 members of one of the most intelligent Farmers' Clubs in England. 
 The Botley Farmers' Club have unanimously resolved, " That 
 where there is not sufficient dung for the wheat crop, it is more 
 profitable to apply concentrated manures than to purchase dung ; 
 and that an equal amount of money expended in the purchase of 
 concentrated manures will raise more wheat than the same amount 
 expended in the purchase of oilcake or corn, and converted into 
 dung by feeding cattle." And the Rev. L. Vernon Harcourt, 
 speaking of this decision of the Club, says, " all my experiments 
 tend to corroborate the view taken by the Botley Club on this 
 subject." 
 
 Leaving these facts and opinions to the consideration of those 
 farmers who seek to combine good farming with economy of 
 manuring, we shall now offer some suggestions as to the best mode, 
 and the proper time, of applying guano to different varieties of 
 crops. 
 
 ON THE MODE OF APPLYING GUANO TO THE SOIL. 
 
 It requires but a short consideration of this subject to perceive, 
 that before any useful practical rules can be obtained for the appli- 
 cation of guano, we must carefully compare the properties of the 
 soil with those of the manure to be applied. Reference must also 
 be made to the different conditions of the atmosphere at different 
 seasons, particularly as respects moisture, dew or rain. The 
 nature of the crop will also materially influence the quantity of 
 guano to be used, and the time of its application. 
 
 Practical men have long been aware of the great difference 
 existing in soils as regards their retentive power for manure. On 
 certain lands, the result of the application of a given quantity of 
 farm-yard dung may be seen for a number of years. On others, 
 the effect of the same quantity ceases to be visible in a very much
 
 ON THE MODE OF APPLYING GTJANO TO THE SOIL. . 91 
 
 shorter period. The former class includes the loams, clays, and in 
 general the heavier descriptions of land ; the latter comprises the 
 sands, gravels, chalks, and other lighter qualities, not inaptly 
 termed by the farmer " hungry soils" 
 
 These varieties of soil differ both in chemical composition and 
 mechanical properties. The heavier in general contain more 
 alumina and oxide of iron than the lighter ones. They are also 
 less porous, even when drained ; their particles are finer, and their 
 absorptive power is greater. The want of great porosity prevents 
 the too rapid action of the atmosphere on the manures they may 
 contain, and their absorptive power enables them to retain, to a 
 considerable extent, the liquid and volatile elements of the 
 manure, and at the same time to obtain a certain quantity at the 
 expense of the atmosphere. 
 
 The case is, however, different with gravels, sands, and the 
 lighter soils ; upon which, in consequence of their greater poro- 
 sity, the atmosphere acts freely, and to a considerable depth. 
 
 When manure is applied to them it is rapidly decomposed, 
 and unless there be a growing crop ready to absorb the fertilising 
 particles as they become soluble, they will be washed away ; or, 
 if they become volatile, will, to some extent, be absorbed by the 
 atmosphere. These soils, therefore, require different treatment. 
 We may apply to heavier lands a strong dressing .of manure at 
 once, and little loss will ensue, for some time at least, from any 
 other source than the action of the growing crops. On the lighter 
 soils, we must use, even of farm-yard dung, a less amount at a 
 time, but it must be applied more frequently. We thus see that 
 light lands have the advantage of more rapidly decomposing the 
 dung, and consequently of preparing it more quickly for the 'use 
 of the plant. For this reason, among others, light soils are pre- 
 ferred by the market gardeners, who, by their repeated manurings 
 and repeated croppings, practically show how these soils may be 
 most efficiently managed. 
 
 It may not be uninteresting here to introduce some experi- 
 ments made at Kennington, with the view of obtaining a further 
 insight into the properties of guano, and the action of light soils 
 upon it.
 
 92 . LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 EXPERIMENT I. 
 
 A small quantity of Peruvian guano was placed in a saucer, and 
 the whole covered with a bell glass containing a slip of red litmus 
 paper, moistened with distilled water. . In the course of an hour 
 or two the slip became distinctly blue.* This proves the escape 
 of a small amount of ammonia from the guano simply by expo- 
 sure to air. 
 
 EXPERIMENT II. 
 
 A quantity of guano was mixed with four or five times its 
 weight of ordinary light garden mould, and slightly moistened. 
 It was covered, as before, with a bell glass. The strip of litmus 
 paper became blue in two or three hours. 
 
 This experiment proves that a small amount of light soil mixed 
 with guano will not prevent the escape of ammonia. 
 
 EXPERIMENT III. 
 
 s 
 
 Two grains of guano were intimately mixed with two thousand 
 grains of light soil, and covered with a bell glass as before. The 
 mixture was slightly damp, but not wet. After the lapse of 
 twenty-four hours, the litmus was very faintly tinged with blue. 
 A little pure distilled water was now added to the mixture. After 
 the lapse of another day, the tinge became much deeper. 
 
 From this it is apparent that even a large excess of soil will 
 not prevent the escape of a certain amount of ammonia. From 
 another experiment, it was evident that even the soil itself exhaled 
 a minute trace of ammonia. 
 
 EXPERIMENTS IV. V. AND VI. 
 
 These were made upon a piece of meadow attached to the 
 College at Kennington. Two portions of land about two months 
 before had been dressed with guano, at the rate of two-and-a-half 
 cwt. and five cwt. per acre, respectively. Another portion received 
 no dressing at all. A bell glass, with moistened red litmus, was 
 deposited carefully, mouth downwards, upon each of the three 
 
 * Ked litmus paper is rendered blue by the action of ammonia and other 
 alkalies. The red colour is restored by acids.
 
 ON THE MODE OF APPLYING GUANO TO THE SOIL. 93 
 
 portions of meadow. After the lapse of a couple of days, it was 
 found that the colour of the litmus had perceptibly changed in each 
 of the bell glasses, but most on the guanoed portions of the land. 
 At the time of making these experiments the wind was N.E., and 
 the temperature very low. 
 
 The grass exhibited little or no signs of growth. 
 
 We infer from these experiments that there is generally a 
 slight escape of ammonia into the air from grass land, manured or 
 unmanured, in those seasons of the year when there is no great 
 activity in vegetable life.* 
 
 EXPERIMENT VII. 
 
 A portion of the mixture of soil and guano in the third experi- 
 ment was placed in a filter paper, and a quantity of pure distilled 
 water was added. The liquid which filtered through was neutral 
 to litmus paper. On being tested, however, in the usual way with 
 hydrate of lime, every precaution being taken, the litmus paper 
 was readily turned blue. 
 
 From this experiment it is apparent that from a mixture of 
 light soil and guano, in the proportion of 1,000 to 1, water is able 
 to dissolve and remove a portion of the ammonia of the guano. 
 
 The difference of soils is not the only consideration ; the climate 
 of different localities in the British Islands is exceedingly various. 
 
 In Ireland, in Scotland, and in the Western districts of Eng- 
 land, from Cornwall to Cumberland, the quantity of rain which 
 falls in the year is probably nearly double that which descends in 
 Suffolk, Norfolk, and on the East coast generally. The air also 
 is constantly more humid, and for this reason those parts of our 
 Isles are well adapted for the growth of root and green crops, and 
 are not so well adapted for wheat. Guano may, consequently, at 
 any time of the year, be there used in larger quantities, without 
 the same danger of burning the crop, which would occur in our 
 Eastern Counties. In these latter districts, the guano should 
 
 * These experiments require to be repeated on various soils, to enable us to 
 draw from them more general truths. 
 
 N
 
 94 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 never be applied as a top-dressing in dry weather, but during a 
 wet or showery day. 
 
 Where wheat is grown in humid climates, it is liable to lodge 
 before harvest, and therefore guano, if used, should be applied 
 with caution to this crop. Two or three cwt. per acre, mixed 
 with four cwt. of salt, is quite sufficient, one half at sowing, and 
 the other in the spring. 
 
 From these and various other ascertained facts, we may deduce 
 the following general rules for regulating the application of 
 guano : 
 
 GENERAL RULES FOR USING GUANO. 
 
 1st. That guano is best applied in damp or showery weather. 
 
 2nd. That guano should not generally be put on grass land in 
 the spring later than April. 
 
 3rd. That when guano is applied to arable land, it should im- 
 mediately be mixed with the soil, either by harrowing or 
 otherwise. 
 
 4th. That when wheat is sown very early in the autumn, a less 
 than usual amount of guano must at that time be applied, 
 and the rest in the spring. The wheat, otherwise, might 
 become too luxuriant, and be injured by subsequent frosts. 
 
 5th. That guano, and artificial manures in general, should be put 
 on the land only in quantities sufficient for the particular 
 crop intended to be grown, and not with the intention of 
 assisting the succeeding one. Each crop should be sepa- 
 rately manured. 
 
 6th. That guano, before application, should be mixed with at 
 least from five to six times its weight of ashes, charcoal, 
 salt, or fine soil. 
 
 7th. The guano should on no account be allowed to come in direct 
 contact with the seed. 
 
 The preceding rules, if duly attended to, will prevent the re- 
 currence of most of those vexatious losses of time and capital, 
 which many, even of our best farmers, have experienced from
 
 MODE OF APPLYING GUANO TO VARIOUS CROPS. 95 
 
 want of a due acquaintance with the properties of concentrated 
 manures. 
 
 In order still further to guard against disappointment arising 
 from the misapplication of guano, we shall now describe the best 
 practical modes of its application to the principal crops which are 
 grown in this country. 
 
 MODE OF APPLYING GUANO TO VARIOUS CROPS. 
 
 PREPARATION OF GUANO FOR SOWING OR DRILLING. 
 
 For drilling, it must first be mixed with four to six times 
 its weight of the ashes * of wood, turf, or coal, or with the same 
 quantity of well sifted mould or salt. Charcoal, in powder, either 
 from peat or wood, is also a most excellent article to be mixed with 
 the guano, in the proportions indicated. Its great porosity allows 
 it to retain the volatile ammonia, and, in dry weather, to absorb 
 considerable moisture from the air. This is of material benefit to 
 plants in their early growth. 
 
 Before mixing, the guano must be finely pulverised, which may 
 easily be done with a common garden roller, upon the floor of a 
 barn or shed, or even by blows from a common shovel. A layer of 
 the ashes, &c., is then spread evenly upon the floor, and a quantity 
 of the fine guano sifted over it. This is followed by another 
 layer of mould or ashes, and another of guano, until the requisite 
 quantity of both is used. The whole must then be repeatedly 
 turned with the shovel, until thoroughly mixed. If time will per- 
 mit, it is now preferable to leave the mixture for eight or ten days. 
 It must then be again sifted, when it will be ready for use. 
 
 * Some varieties of wood ashes, which contain a considerable amount of 
 free alkali, are not suitable for mixing with, guano, as they liberate the am- 
 monia. This may easily be shown by mixing a shovel full of the ashes with 
 the same quantity of guano. If a. strong ammoniacal odour be immediately 
 perceived, the ashes are not fit to be mixed with guano. The mode of prepara- 
 tion here described should be used, with slight variations, according to circum- 
 stances, for all varieties of crops J. C. N. 

 
 96 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 In using guano with the drill, care must be taken that the 
 mixture fall below the seed, and that an inch or 'so of soil intervene 
 between them, otherwise the strength of the guano will kill the 
 seed. Garrett's, Ilornsby's, and other modern drills, are well 
 adapted for depositing guano and other concentrated manures. 
 
 The above mixture is generally sufficiently damp to fall exactly 
 where the hand directs it. When this is not the case, a small 
 quantity of water must be added ; the field must be sown with the 
 mixture in the ordinary manner, and the manure harrowed in ; the 
 seed is then drilled as usual. 
 
 Perhaps the preferable mode would be, to broadcast two-thirds 
 of the guano applied, and to drill one-third with the seed. The 
 young plants would then have enough manure under the drills to 
 serve the early stages of growth, while the guano sown broadcast 
 would supply the wants of the plants in a more mature state, when 
 the roots would have spread in every direction in the soil. 
 
 WHEAT, BARLEY, OATS, AND OTHER CEREALS. 
 
 The researches of modern chemistry have in no respect proved 
 of greater benefit to practical agriculture, than in the analysis and 
 estimation of the components of different manures, and in the 
 careful examination of the effects of these components on different 
 crops, when applied either alone or combined. This is, in fact, the 
 only philosophical mode of arriving at a true knowledge of the 
 manuring substances best adapted for the development of various 
 forms of vegetable life. 
 
 From the analyses of thousands of samples of manure in the 
 laboratories of the college, and from a knowledge of the effects 
 produced by these manures on a variety of crops, the conclusion 
 has been irresistible, that NITROGEN is the cheapest substance to 
 apply to cereals. The same conclusion has been arrived at by 
 numerous other chemists. The results also of the experience of 
 farmers in all parts of the country, for many years, is, that nitrogen, 
 in any of its ordinary combinations, is the matter of all others best 
 adapted for the growth of wheat and other cereals, and which for 
 these crops will yield the greatest per centage of profit.
 
 MODE OF APPLYING GTTANO TO VAKIOTJS CROPS. 97 
 
 Not that corn requires no phosphates or other materials for its 
 development, but that the latter are generally supplied to the soil 
 for other crops in the ordinary course of rotation, or, as in the case 
 of guano, are found in the manure itself. The market value of 
 nitrogen of course varies with the source of its supply, and with 
 the rise and fall in price of its various combinations; but at 
 the present comparative price of guano, this substance appears to 
 be nearly, if not altogether, the cheapest source of nitrogen, at 
 least in any considerable quantity. 
 
 There can be no doubt of the vastly increased production 
 of corn, and consequently of profit to the farmer, which would 
 accrue, if guano were more extensively used. 
 
 Our most intelligent agriculturists, among whom we may 
 mention Mr. Caird and Mr. Lawes, agree that the application 
 of two cwt. per acre, will give an increase of between eight 
 and nine bushels of grain, besides one fourth more straw than 
 usual. 
 
 Mr. Caird * has proved that without any increase of rent or 
 taxes, an expenditure of twenty shillings per acre produces a net 
 profit of thirty-two shillings and sixpence. If these facts were 
 more generally known, it is impossible to believe that farmers would 
 not at once avail themselves of the opportunity of making a profit 
 of more than one hundred and fifty per cent, upon the annual 
 additional outlay. 
 
 Many farmers prefer using the whole of their guano for wheat 
 in the autumn. A portion, at all events, should be sown broadcast 
 at that period. This is more especially needful if no dressing of 
 farm-yard dung be used. 
 
 If guano be used for wheat, in lieu of farm-yard dung, a 
 greater quantity, often the whole, ought to be applied in the 
 autumn. Care, however, must be taken not to stimulate the plant 
 too much, otherwise it will be liable to suffer injury from frost. 
 One cwt. or two cwt. per acre on light lands can be applied broad- 
 cast, and harrowed in during autumn, either before or after the 
 drilling of the wheat. 
 
 * See Mr. Caird's Letter, at the end of this Essay.
 
 98 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 In the spring, a further application of not more than one cwt. or 
 two cwt. may be made, harrowed in with light harrows. If the 
 wheat be drilled sufficiently apart to allow of horse-hoeing, it will 
 be found advantageous. 
 
 Should wheat, manured with dung as usual, look unkindly in 
 the spring, it will be greatly benefited by a dressing per acre of 
 two cwt. of guano, and four cwt. of salt. Salt has great effect in 
 strengthening the straw of wheat and other cereals, and where any 
 of these crops are liable to lodge, or whenever guano is used, four 
 cwt. or five cwt. of salt should always be sown per acre. For barley 
 and oats, two cwt. of guano, and four cwt. of salt, may be sown 
 broadcast per acre, the seed drilled, and the whole harrowed in 
 together. 
 
 TURNIPS. 
 
 For this crop guano may be applied, either broadcast or by 
 drill, mixed as previously shown. The quantity of guano to be 
 used per acre will vary with the condition of the farm. About 
 two to three cwt. may be applied with advantage, and six cwt. have 
 been used with safety on heavy soils. Two cwt. or three cwt. 
 sown broadcast, and one cwt. drilled with the seed, will probably 
 give the best chance for a successful result. 
 
 Experiments have proved that, when a portion of guano is 
 applied between the drills, and well horse-hoed in after the turnips 
 are up, that large crops are obtained. It is questionable whether 
 this is not one of the best means of applying guano, as on light 
 soils there is less liability to loss in the guano, and the roots of the 
 turnip are supplied with fresh manure at a vigorous period of their 
 growth. Two cwt. or three cwt. broadcast before the turnips are 
 sown, and one cwt. between the drills afterwards, will be found 
 sufficient. 
 
 A combination of superphosphate of lime with guano has 
 been used with much success. For this purpose, two cwt. or three 
 cwt. of guano is sown broadcast, and the same quantity of super- 
 phosphate of lime, mixed with ashes, drilled with the seed.* 
 
 The prize for the best forty acres of Swedes in one of our most important 
 agricultural counties, was taken by a gentleman who followed this plan.
 
 MODE OF APPLYING GUANO TO VARIOUS CHOPS. 99 
 
 We may here suggest to some of our intelligent practical 
 fanners, to try the effect upon the turnip crop of a mixture of 
 Peruvian guano and sulphuric acid. 
 
 Sulphuric acid is undoubtedly a manure per se, audit seems to 
 exert a specific effect on the turnip. A mixture might be made of 
 four cwt. of guano, and one cwt. of white acid, of sp. gr. 1.84-. 
 The guano must be laid in a heap, a hollow made in the centre, 
 and the sulphuric acid must be poured into it; the whole should 
 then be well worked together with a spade or other instrument. 
 Considerable chemical action will take place, but in a short time 
 the whole will become dry and ready for the drill. If the brown 
 acid, of sp. gr. 1.7, be employed instead of the white, one-fourth 
 more must be used. The above quantity will be sufficient for 
 two acres. We believe that a mixture of this kind will prove a 
 most efficient manure. 
 
 It is of some importance to remember, that in using guano for 
 turnips and other roots, that the whole of the nitrogenous matter 
 is not taken out by the crop, but that a portion is left for the sub- 
 sequent corn crop. Large quantities of guano are used for heavy 
 land, by many of our best Essex farmers, on mangel as a good pre- 
 paration for wheat, the mangel being wholly withdrawn from the 
 field. 
 
 MANGEL WURZEL. 
 
 Guano is an excellent manure for this crop. On heavy and 
 loamy soils the land is ploughed, and ten or twenty tons of farm- 
 yard dung are worked into the soil before Christinas, if possible. 
 Two or three weeks before drilling the seed, four cwt. of guano, with 
 an equal weight of common salt, is sown broadcast over the field 
 and well harrowed in. The seed is drilled in the usual way, and at 
 thirty to forty inches apart. In thinning the plants afterwards, they 
 should not be left too close together. Repeated horse-hoeings 
 between the rows is of great importance, for air and nutriment are 
 thus admitted to the roots of the plants. As in the case of the 
 turnips, great advantage will be obtained by occasionally sprinkling
 
 100 LKCTURK8 ON AGRICULTURAL CHEMISTRY. 
 
 a little guano between the rows previously to the hoeing. This 
 insures continued nutriment to the plants. 
 
 When no farm-yard dung has been applied in winter, six 
 cwt. of guano may be used instead of four cwt. On heavy land 
 this may be put on either in the autumn or spring, and well worked 
 into the soil, following this up by a small dressing afterwards 
 between the drills at the time of hoeing. The land in either case 
 will be left in good condition for wheat. 
 
 On light chalky soils, a mixture of guano, nitrate of soda, 
 and common salt, at the rate of two cwt. each per acre, has been 
 found very efficacious in the growth of mangel wurzel. 
 
 GRASS. 
 
 The experiments of Kuhlmann, the French Agricultural Che- 
 mist, upon the action of ammonia on grass lands, at once point to 
 guano as one of the most important manures for increasing the 
 productive power of our pasture and meadow land. This chemist 
 applied ammonia in different forms, alone and combined with other 
 simple mineral manures, and he found that in all cases the amount 
 of grass or hay produced was in exact proportion to the amount 
 of nitrogen contained in the manure. Guano containing a large 
 amount of ammonia, and being also, at present, its cheapest source, 
 must, therefore, prove of great benefit in the production of grass. 
 
 For grass land, from two to four cwt. of guano, mixed with soil, 
 may be used per acre. Wet or damp weather should be selected for 
 sowing it. Probably the end of March or the beginning of April 
 is the best time. Under certain circumstances, guano may be 
 applied to grass land in the autumn, particularly where the under 
 soil is of a strong or loamy character. Thus applied, it will have 
 the effect of bringing up the grass earlier in the spring. 
 
 
 
 POTATOES. 
 
 From the comparison of numerous series of experiments, it 
 would appear that guano succeeds best with this crop as a top- 
 dressing, in conjunction with farm-yard dung. The ground is
 
 MODE OF APPLYING GUANO TO VARIOUS CROPS. 101 
 
 prepared in the usual manner. The farm-yard dung is deposited 
 in the bottoms of the drills, the sets of the seed potatoes laid upon 
 the top of the manure, and the whole earthed up. Before the 
 plants appear, the guano is to be sown on the top of the drills, 
 covered over with the plough, and then rolled. If the potatoes be 
 grown on the level, and not in drills, the guano may be sown over 
 the field broadcast, two or three weeks after the potatoes have been 
 planted. The quantity of guano to be used per acre is from 
 three cvvt. to six cwt. 
 
 Many experiments have proved the great utility of sulphate of 
 soda, or sulphate of magnesia, in conjunction with guano, upon 
 this crop. As far as our own experience goes, these salts have a 
 decided effect in diminishing the liability of potatoes to disease. 
 We should, therefore, recommend, in addition to the guano, to put 
 per acre, at the same time, 
 
 1 cvvt. of sulphate of soda, and 
 1 cwt. of sulphate of magnesia. 
 
 If farm-yard dung be not used for potatoes, broadcast and 
 harrow in three cwt. or four cwt. of guano, and set the potatoes as 
 usual. Three or four weeks afterwards, sow over them, and 
 lightly harrow in, the same quantity of guano, and one ewt. each 
 of the sulphates of soda and magnesia. 
 
 The mixture of sulphuric acid and guano mentioned at page 
 99, under the head of turnips, would probably be found an ex- 
 cellent manure for this crop. 
 
 Near the Humber, as much as ten cwt. annually is used for 
 potatoes, with extraordinary results. 
 
 BEANS, PEAS, AND LEGUMINOUS PLANTS. 
 
 For beans or peas, two cwt. or three cwt. per acre may be used, 
 either broadcast before sowing, or a portion afterwards between the 
 drills at the time of horse-hoeing. The latter would probably be 
 the better plan. 
 
 For vetches, lucerne, saintfoin, or clover, two cwt. or three cvvt.
 
 102 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 per acre broadcast may be used. This should be sown in the be- 
 ginning of April, on a dewy morning, or during wet weather. It 
 is useless to sow if there be a probability of dry weather ensuing 
 for any lengthened period. 
 
 FLAX. 
 
 This crop, in olden time, had the renown of being one of the 
 most exhausting crops which could be put into the land. We 
 have now learned that white crops, and those in general which 
 have the repute of " drawing the land" are those which require 
 the largest amount of nitrogen for the formation of seed, and for 
 which, consequently, ammoniacal manures are precisely adapted. 
 With the aid of guano, or other ammoniacal manures, flax can no 
 longer be considered an exhauster of the soil. 
 
 In using guano for this crop, from two cwt. to four cwt. per 
 acre, mixed with ashes, may be sown broadcast and harrowed in, 
 a few days before the seed is drilled. 
 
 CABBAGE, CARROTS, &c. 
 
 Guano has been found of material benefit for these crops, and 
 may be employed advantageously at the rate of from two cwt. to four 
 cwt. per acre. It must be remembered that carrots require deep 
 cultivation, and that both crops will be benefited by the proper 
 stirring of the soil between the rows, and the occasional addition 
 of a little guano. 
 
 HOPS. 
 
 To no crop does the addition of a proper amount of ammoniacal 
 manure prove more advantageous than to the hop. The constant 
 withdrawing of the hops, year by year, from the land, necessitates the 
 importation upon the soil of a considerable amount of both mine- 
 ral and organic ingredients. Four cwt. of guano and three cwt. 
 of salt per acre, applied at two separate times, and well worked 
 in between the alleys, will be found a useful application. Or the 
 manure may be put round each hill, and covered up with the soil. 
 
 From several analyses of the hop plant, the following mixture
 
 THE COMPOSITION OF GUANO. 103 
 
 was recommended by the Author, some years ago, as a proper 
 manure for the hop : 
 
 MANURE FOR AN ACRE OF HOPS. 
 
 3 cwt. of guano, 
 
 I cwt. common salt, 
 
 I 1 cwt. saltpetre, or nitrate of soda, 
 1 cwt. gypsum. 
 
 This manure has been used with considerable success in various 
 parts of Surrey, Kent, and Sussex. 
 
 It will not be necessary to give any further details of particular 
 crops for which guano is suitable, or to describe more fully the 
 mode of its employment. The intelligent farmer will soon learn 
 to vary its application to suit the end he may have in view. 
 
 Guano, however, is useful to others besides the farmer. To 
 the horticulturist it is invaluable, and many specimens of the finest 
 vegetables and fruits, and of the most beautiful flowers, have been 
 indebted to the judicious use of guano for the admiration they 
 have excited, and the prizes they have obtained. 
 
 For further particulars respecting its horticultural use, we must 
 refer the reader to the columns of the " Gardeners' Chronicle." 
 And in concluding this part of our subject, we cannot refrain from 
 quoting the opinion of Dr. Lindley, the learned editor of that 
 valuable journal, that " If the experience of the last few years has 
 taught us one thing more certainly than another, it is the unfailing 
 excellence of guano for every kind of crop which requires manure" 
 
 THE COMPOSITION OF GUANO. 
 
 Our space will not permit us to describe all the varieties of 
 proximate elements contained in different samples of guano. Nor 
 is it, indeed, necessary for the practical man to be acquainted with 
 them, as the commercial value of guanos is best determined by the 
 amount of nitrogen (ammonia) and phosphate of lime they contain.
 
 101 LECTURES OX AGRICULTURAL CHEMTSTRT. 
 
 For more minute information on this subject, the reader is 
 referred to Dr. Ure's paper on guano, in Vol. V. of the " Journal 
 of the Royal Agricultural Society." 
 
 In this inquiry we have devoted our observations more espe- 
 cially to the Peruvian guano, as the quantity of this article at pre- 
 sent brought into the market very far exceeds that of all the other 
 kinds of guano put together. 
 
 A word or two may not, however, be out of place respecting the 
 other varieties, the principal of which are the Angamos, the Chilian, 
 the Bolivian, the Saldanha Bay, and the Australian. The island 
 of Ichaboe, on the African coast, furnished a few years back large 
 supplies of a medium guano. It is now, we believe, wholly ex- 
 hausted. 
 
 The Angamos guano is from the western coasts of South Ame- 
 rica. It is the most recent deposit of the birds, collected by hand, 
 with considerable danger and difficulty, from the bare surfaces of 
 the precipitous rocks which they frequent. When pure, it is of 
 first-rate quality, and having suffered no decomposition, frequently 
 contains from 20 to 24< per cent, of ammonia. The small ness of 
 the quantity, however, that can be collected, renders it of little 
 general importance to the farmer. 
 
 The Saldanha Bay, and other varieties, having been deposited 
 in rainy climates, have suffered great deterioration. The valuable 
 ammoniacal salts and soluble phosphates have been in great mea- 
 sure washed away, the nitrogenous animal matter has been decom- 
 posed, and little remains but the common phosphate of lime. The 
 Chilian and Bolivian are often contaminated with large quantities 
 of sand, and the Shark's Bay (Australian) guano, is certainly not 
 worth the carriage to this country. The farmer ought at no time 
 to buy any of these descriptions of guano without an accurate 
 analysis, as, owing to their varying impurities, it is otherwise pos- 
 sible that he may pay for them several pounds per ton above their 
 real value. 
 
 An idea of the great difference of composition which exists in 
 samples of guano from distinct localities, can only be formed by a 
 comparison of their respective analyses. To enable the agricul-
 
 OX THE ADULTERATION OF GUANO. 
 
 105 
 
 turist to form a correct judgment of the kinds now in the market, 
 we give a table of the composition of six varieties. 
 
 ANALYSES OF DIFFERENT VARIETIES OF GUANO. 
 
 Moisture 
 
 Angamos i Angamos Peruvian 
 Guano. ; Guano. Guano. 
 
 Chilian Bolivian 
 Guano. Guuno. 
 
 Saldanha 
 Bay Guano. 
 
 Sharks' 
 Bay Guano. 
 
 10-90 12-55 9-30 
 67-36 61-07 5730 
 1-04 5-36 0-75 
 16-10 13-76 23-05 
 4-60 7-26 9-60 
 
 2046 16-00 
 18-50 13-16 
 22-70 3-16 
 31-00 60-23 
 7-54 7-45 
 
 17-92 
 14-08 
 2-80 
 59-40 
 5-80 
 
 14-47 
 7-85 
 14-47 
 29-54 
 33-67* 
 
 Organic Matter, &c. 
 Sand, &c 
 
 Phosphates 
 
 Alkaline Salts, &c . . 
 
 Nitrogen (equal to) 
 Ammonia 
 
 100-00 ! 100-00 100-00 
 19-95 1 18-24 i 15-54 
 24-19 , 22-12 ! 18-87 
 
 100-00 100-00 
 4-50 2-11 
 5-47 2-56 
 
 100-00 
 0-63 
 0-76 
 
 100-00 
 0-35 
 0-47 
 
 
 We may here caution the farmer not to put any trust in those 
 analyses, often placed in his hands, which merely indicate that the 
 sample analysed contains such and such a per-centage of animal 
 organic matter, or of salts of ammonia. 
 
 From these deceptive analyses, it is perfectly impossible even 
 for the most experienced chemist to obtain the slightest notion of 
 the value of a manure ; and we recommend the farmer, under no 
 circumstances, to buy a guano, unless the precise amounts of 
 ammonia and phosphate of lime are distinctly mentioned. 
 
 Should the farmer wish to prepare a sample, for chemical 
 analysis, half a pound should be taken from each of five or six bags 
 containing the bulk. These should be mixed together on a sheet of 
 brown paper, until thoroughly incorporated and homogeneous. Two 
 or three ounces of the mixture is enough for analysis ; and it can 
 easily be sent per post from any part of the kingdom. To prevent 
 evaporation from the sample, it can be wrapped up in tinfoil, or 
 lead leaf from a tea chest, and afterwards in paper. If the tin- 
 foil cannot be procured, two thicknesses of strong paper should be 
 used. 
 
 * 29-54 per cent, of this was gypsum. The above 'are analyses made in the 
 Kennington Laboratories. The samples were from cargoes received in London 
 within the last six months. The Chilian and Bolivian guanos are much infe- 
 rior to those formerly imported, in consequence, we believe, of all the finer 
 qualities having, for some time, been worked out.
 
 106 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 In order to furnish a standard of comparison to the farmer 
 who may think it desirable to ascertain the composition and value 
 of the guano he purchases, we subjoin an analysis of an ordinary 
 sample of Peruvian guano, recently imported. 
 
 Analysis of an average sample of Peruvian Guano. 
 
 Moisture 1 5-10 
 
 Organic Matter, &c 51-27 
 
 Silica 2-20 
 
 Phosphate of Lime 22-13 
 
 Phosphoric Acid (equal to] 3'23 
 
 Phosphate of Lime 7'00 
 
 Alkaline Salts, &c 6 07 
 
 10000 
 
 Nitrogen 13-54 per cent. 
 
 Ammonia . .... 16-42 
 
 ON THE ADULTERATION OF GUANO. 
 
 After the observations we have made on the utility of guano to 
 those engaged in agricultural pursuits, it would have been very 
 gratifying to have concluded our remarks. 
 
 It is, however, our invidious duty to refer to a less pleasing, 
 but not less important, part of the subject. 
 
 The high manuring value of guano, and its extensive sale, 
 combined with the want of knowledge among farmers as to the 
 genuineness of the article, and their manifest reluctance to be at 
 the expense of a chemical analysis, have, together, induced many 
 fraudulent dealers to adulterate this manure systematically, to a 
 great extent. The strong desire which unfortunately exists among 
 a large class of farmers to purchase guano at the lowest terms per 
 ton, without due reference to the quality or composition of the 
 manure, has also operated most materially to their own disadvan- 
 tage. 
 
 If the honest dealer offers a genuine article in the market, upon
 
 ON THE ADULTERATION OF GUANO. 107 
 
 which he puts only a reasonable profit, and finds that his roguish 
 neighbour can more readily sell an adulterated article, he has no 
 alternative but to abandon the trade or to turn rogue himself. 
 The man who likes cheap manures should be reminded that to the 
 buyer they are always dear, as he has to pay the whole expense of 
 adulteration, as well as the twenty or thirty per cent, profit of the 
 dishonest, dealer. In fact, we should recommend the lovers of cheap 
 manures to follow, in preference, the example of Q,uin, who finding 
 his milk more than half water, armed with two jugs, demanded of 
 his milkman " to give him them separate, he could mix for him- 
 self." 
 
 It is, indeed, scarcely possible to give persons at a distance an 
 idea of the extent to which guano is adulterated in London and 
 some other large towns. 
 
 The demand of the farmer for cheap manure, acting upon the 
 trade through the medium of the unscrupulous dealer, has given 
 rise to a fraudulent and hitherto successful business. 
 
 A most extensive and profitable trade is at present carried on 
 by parties who practise the compounding of specious-looking 
 ARTICLES, to mix with guano ; these they supply to dealers in that 
 manure. 
 
 The materials used to sophisticate guano are numerous. 
 
 Sand, marl, clay and chalk, limestone, bricks, tiles, gypsum 
 ground, when necessary, to a fine powder constitute the materials 
 for which the farmer is destined to pay 8 or 10 per ton. The 
 marls of Stratford, Wanstead, and other places in Essex, and the 
 yellow loams of Norwood, in Surrey, are in particular request. 
 These, mixed in proportions to counterfeit the colour of guano, 
 are sold to roguish dealers in town and country, who introduce a 
 little genuine guano to give the necessary odour. Some recent 
 actions brought against parties who have sold adulterated guano, 
 in which heavy damages were obtained, and the failure of several 
 of the largest of the manufacturers of the " ARTICLE," have con- 
 tributed some little to arrest this nefarious traffic. The real 
 remedy lies with the farmer, who ought to prosecute vigorously 
 those who impose upon him.
 
 108 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 Though numerous unprincipled dealers exist in the manure 
 trade, yet there are certainly many others, honest men, upon whose 
 fair fame there has never yet been a breath of suspicion. 
 
 We advise the farmer, therefore, to purchase his manures from 
 men of established reputation, who have a character to lose, and who 
 will not demand from him more than a fair and reasonable profit. 
 
 It should also be remembered that 11 per ton is the lowest 
 price at which Messrs. Ant. Gibbs and Sons sell Peruvian guano ; 
 and this only in wholesale quantities. The country dealer has, in 
 addition, to pay wharfage, carriage and other expenses, which must 
 be added to the cost of the guano. He is also entitled to a rea- 
 sonable interest for his money, if he gives long credit for that 
 manure which he himself is compelled to pay for in cash. 
 
 We leave it, therefore, to the common sense of the English 
 farmer to judge whether a genuine guano can possibly be pur- 
 chased at the prices at which guanos, purporting to be genuine, are 
 constantly offered in the country markets. 
 
 Tc assist still further in preventing the frauds to which the 
 incautious buyer is continually subject, we shall olfer some simple 
 observations on the methods of detecting adulterations in guano. 
 
 METHODS OF DETECTING THE ADULTERATION OF GUANO. 
 
 The chemical analysis of guano is, of course, the best means 
 of ascertaining any fraudulent mixture which may have been 
 made ; and it is a subject of regret that few farmers yet avail 
 themselves of chemical aid, though the expense of the necessary 
 information is quite insignificant compared with the importance of 
 the object to be attained. 
 
 It has long been a desideratum to obtain some method of ascer- 
 taining the purity of guano, sufficiently simple to be easily under- 
 stood and put in practice by any person of ordinary intelligence. 
 With this object in view, we have tried in our laboratory many 
 long series of experiments. These have ultimately led us to pro- 
 pose a few simple tests, which will readily discover the adulterations 
 iu any sample of sophisticated guano which has yet appeared in 
 the market.
 
 ON IHE ADULTERATION OF GUANO. 109 
 
 As guano is generally adulterated with marls and sands, much 
 heavier than itself, our attention was first directed to the specific 
 gravity of guano as a means of detecting the admixture. 
 
 In a lecture delivered some time since before the London 
 Farmers' Club, we had shown that an ounce of good guano, put 
 into a cylindrical glass tube, occupied nearly twice the space of an 
 equal weight of an adulterated sample. We subsequently tried 
 many hundreds of experiments with various guanos, in tubes of 
 like dimensions, but though the tube easily detected all the adulter- 
 ated samples we procured, yet it was thought desirable to propose 
 some more delicate test. 
 
 Various other experiments were undertaken, and the following 
 series gave us the necessary foundation for the method we ulti- 
 mately selected. 
 
 A stoppered bottle, capable of holding 3,000 grains of water, 
 had four ounces avoirdupois of good guano placed in it. Water 
 was then added, and the materials shaken until well mixed. A 
 little more water was added, and the bottle again agitated, and then 
 allowed to rest for three or four minutes to permit the air bubbles 
 to arise. The bottle was now filled completely with water, the 
 froth running over ; the stopper was then gently, but accurately, 
 fitted to its place, and the bottle wiped with a cloth. 
 
 A counterpoise, previously made equal to the weight of the 
 bottle alone, was then placed in one pan of a small pair of ordi- 
 nary scales, and the bottle, with the guano, in the other. From a 
 numerous series of experiments, it was found that the bottle and 
 guano, on an average, weighed 664 grains more than the bottle and 
 water alone : that is, the water in the bottle would weigh 3,000 
 grains, and the guano and water 3,664 grains. 
 
 The following table contains the results of a long series of 
 experiments made upon specimens of genuine guano obtained 
 from separate vessels, and also upon various sophisticated samples, 
 and substances used for adulteration.
 
 LECTUUKS ON ACi RICULTUHAL CHKMI8TKY. 
 
 WEIGHTS INDICATED BY GUANO TESTER. 
 The Bottle holding 3.000 grains of water. 
 
 1 
 2 
 3 
 4 
 5 
 
 7 
 8 
 B 
 10 
 
 11 
 
 12 
 13 
 14 
 
 15 
 16 
 17 
 18 
 19 
 20 
 21 
 22 
 23 
 24 
 25 
 26 
 27 
 28 
 29 
 30 
 31 
 32 
 33 
 34 
 35 
 
 .Name i'f \ i -.*!. 
 
 Field 3663 
 
 Columbia 3602 
 
 I'rinc.BS Victoria 3G68 
 
 Digby 36IJ5 
 
 Liskcard 3655 
 
 Duncan .Ritchie 3669 
 
 Kosina 3677 
 
 Mary Ann 3668 
 
 Albyii 3679 
 
 Johann George 3661 
 
 Rosamond ^645 
 
 Ann Dashwood 3648 
 
 Alfred 3645 
 
 J uno i 3659 
 
 Brothers 3665 
 
 Richardson 364 1 
 
 Hamilton 3679 
 
 Anna 3677 
 
 Midas 36u9 
 
 Will Williuot 3659 
 
 Macdonell 3653 
 
 Cumberland 3651 
 
 Retriever 3677 
 
 Lacy 3677 
 
 S'igilaut . . . .' 3669 
 
 Julius Caesar (damaged) 3719 
 
 Vicar of Bray (damaged) 3703 
 
 Field, adulterated 10 per cent 3709 
 
 Ditto 20 per cent 3757 
 
 Ditto 30 per cent 3815 
 
 Guano, 7 lOf. per ton (adulterated) j 3367 
 
 Guano, 7 12s. 6d. per ton (ditto). ; 3894 
 
 Onto, 
 
 Salt 
 Sand . . 
 Gvnsmn 
 
 3930 
 4095 
 4065 
 
 The per centage of mineral matter or ash in different samples 
 of guano was found also very uniform, varying, as the following 
 table shows, only from 30 per cent, to 35 per cent.
 
 ON THE ADULTERATION OF OUAXO. 
 
 Ill 
 
 Table of the per Ceiitaffe of Mineral Matter contained in 
 Peruvian Guano. 
 
 Name of Vessel. Per cent, of Ash. 
 
 | 
 
 1 Johann George 33-4 
 
 2 Ann Dashwood 32-2 
 
 3 Alfred 32-0 
 
 4 j Juno 32'3 
 
 5 Brothers 33'2 
 
 6 j Richardson ... 30'7 
 
 7 Hamilton 33'4 
 
 8 Anna 32'5 
 
 9 Midas 33-0 
 
 10 Will Willmot 34 
 
 1 1 Macdonell 33'1 
 
 12 Cumberland 32-3 
 
 13 Retriever 31-9 
 
 14 Lucy 318 
 
 15 Vigilant 3-5 
 
 16 Rosamond 35'0 
 
 17 Julius Ccesar (damaged) 38-2 
 
 18 Success (dito) 33-6 
 
 19 Guano, 7 10s. per ton (adulterated) . . 62-7 
 
 20 Guano, 7 12s. per ton (ditto) 65-8 
 
 From the experiments detailed on page 110, is deduced the 
 following simple plan, which will easily detect all the ordinary 
 adulterations of guano. 
 
 Procure from any druggist a, common wide-mouthed bottle 
 with a solid glass stopper ; one known as a wide-mouthed six-ounce 
 bottle will do very well. Let this bottle be filled with ordinary 
 water, the stopper inserted, and the exterior well dried. The 
 scales to be used ought to turn well with a couple of grains. In 
 one pan of the scales place the bottle, and exactly counterpoise it 
 in the other by shot, sand, or gravel. Remove the bottle from the 
 scale, pour out two-thirds of the water, and put in four ounces avoir- 
 dupois of the guano to be tested. Agitate the bottle, adding now 
 and then a little more water ; let it rest a couple of minutes x and 
 fill with water, so that all the froth escapes from the bottle ; insert 
 the stopper carefully, wipe dry, and place the bottle in the same
 
 112 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
 scale from which it was taken. Add now to the counterpoised scale 
 one-and-a-half ounce avoirdupois, and a fourpenny piece, and if the 
 bottle prove the heavier, the guano is, in all probability, adulterated. 
 Add in addition a threepenny piece to the counterpoise, and if 
 the bottle and the guano prove the heavier, the guano may be con- 
 sidered as adulterated. By this simple experiment, the admixture 
 of a very small amount of sand, marl, &c., is distinctly shown. 
 
 We venture also to propose another method, founded on the 
 properties of the mineral constituents of guano. When guano is 
 burnt to ashes at a red heat, the ash has a pearly white appearance, 
 which is owing to the absence of iron and other colouring metallic 
 oxides. 
 
 As iron is always found in marl, clay, &c., the ash of any 
 sample of guano contaminated with them will not only be coloured, 
 but its weight will be increased. 
 
 These facts give us the following method of detecting adul- 
 teration. 
 
 A small pair of scales, a little platinum capsule, a pair of little 
 tongs or pincers, and a spirit lamp, are all that are required. Ten 
 grains of the guano are placed in the platinum capsule, which is 
 held by the tongs in the flanje of the spirit lamp for several minutes, 
 until the greater part of the organic matter is burnt away. It is 
 allowed to cool for a short time, and a few drops of a strong solution 
 of nitrate of ammonia added, to assist in consuming the carbon in 
 the residue. The capsule is again gently heated (taking care to 
 prevent its boiling over, or losing any of the ash), until the moisture 
 is quite evaporated. A full red heat must then be given it, when, 
 if the guano be pure, the ash will be pearly white, and will not 
 exceed three-and-a-half grains in weight. If adulterated with 
 sand, marl, &c., the ash will always be coloured, and will weigh 
 more than three-and-a-half grains. 
 
 Even the simple burning of a few grains of guano, on a red- 
 hot shovel, will often indicate by the colour whether a fraud has 
 been committed; but we cannot particularly recommend this 
 method, as the iron of the shovel will itself sometimes give a tinge 
 to the ash.
 
 ON THE ADULTERATION OF GUANO. 113 
 
 It will be perceived, that the per centage of ash will not 
 always detect damaged guano, nor are the tests generally intended 
 to apply to wet or moist samples, which are palpably from damaged 
 cargoes. Good Peruvian guano is perfectly dry to the touch. 
 
 If the adulteration be made with light or flocculent matters, 
 they may be detected easily, as follows : Dissolve in a quart of 
 water as much common salt as it will take up, and strain the 
 solution. Pour a quantity of it into a saucer or basin, and sprinkle 
 on the surface the guano to be tested. Good guano sinks almost 
 immediately, leaving only a very slight scum. The adulterated 
 leaves the light materials floating on the water. 
 
 If chalk or ground limestone be used, it may be shown by 
 pouring strong vinegar over a teaspoonful of the sample placed in a 
 wine glass. On stirring, effervescence shows its presence. Gen- 
 uine guano, under the same circumstances, merely allows the escape 
 of a few air bubbles. 
 
 If farmers could be prevailed upon to spend a small portion of 
 their time in trying the foregoing simple experiments on the 
 samples of guano they use, the fraternity of rogues would certainly 
 have far less chance than they at present possess of pursuing their 
 calling with profit. Still these little operations are only offered as 
 a means of detecting the grosser adulterations of guano. Minor 
 ones may still be practised, and men of real intelligence and 
 business habits will regularly call to their assistance the aid of the 
 analytical chemist. 
 
 Summing up the experiments, the following facts would 
 appear : 
 
 1st. If four oz. of guano, weighed with bottle and water, as pre- 
 viously directed, take more than one-and-a-half oz. and one 
 fourpenny piece to recounterpoise it, its purity is doubtful. 
 If an additional threepenny piece is required, the guano 
 may be considered as adulterated, and the sample should be 
 immediately analysed. 
 
 2nd. If the ash be coloured in any way, and not of a pearly whi^e, 
 the guano is bad.
 
 114 LKCTURES OX AGRICULTURAL CIIFMI8TRT. 
 
 3rd. If the ash of ten grains of the guano weigh more than three- 
 and-a-half grains, or less than three grains, the genuineness 
 of the sample is doubtful. 
 
 1th. If strong vinegar cause a considerable effervescence when 
 mixed with the sample, the latter is adulterated. 
 
 5th. If the guano floats, when sprinkled on a strong solution of 
 salt and water, it is not genuine. 
 
 Note. A complete set of the Apparatus necessary for making the pre- 
 vious experiments, can be obtained at a moderate cost from Messrs. SIMPSON, 
 MAULK, and NICHOLSON, Operative Chemists, 1 and 2, Kennington lload, 
 London. 
 
 PRACTICAL EXPERIMENTS WITH GUANO. 
 
 Our limits will only permit us to introduce a few out of the 
 numerous experiments made with this manure. For more 
 extensive details, the reader is referred to the Journal of the 
 Royal Agricultural Society, the Transactions of the Highland 
 Society of Scotland, the Journal of the West of England Society, 
 the Mark Lane Express, the Gardeners' Chronicle and Agricultural 
 Gazette, Bell's Weekly Messenger, &c. 
 
 EXPERIMENTS OF MR. CAIRD. 
 
 Letter in the " Times," September 10th, 1853. 
 
 "The use of guano has been with me, as with many others for 
 the last ten years, a matter of system, and I have frequently satis- 
 fied myself by experiment of the profit attending its application. 
 To apply it to the wheat crop is the rule not to apply it, the 
 exception. Last autumn, in sowing a large field, exactly 100 
 acres, I directed the person who was laying on the guano to pass 
 over an acre in the centre of the field, all the rqet of which received 
 two cwt. per acre, at the time the wheat was sown. The produce 
 of this and the adjoining acre were cut, and kept separate from each 
 
 other, and from the rest of the field, and were threshed last week, 
 
 
 yielding as follows :
 
 I'llACTiCAL EXPERIMENTS WITH GUANO. 115 
 
 Bushels. Cwt. 
 
 One acre, with two cwt. of guano 41 and straw 40 
 
 One acre, without guano 35 30 
 
 Increase of wheat 9 and straw 10 
 
 " The cost of the guano (Peruvian) on the field was 10s. per 
 cwt., or 1 an acre, so that I have nine bushels of wheat for 1. 
 The acre selected for the experiment was an average of the field, 
 and I have no reason to doubt that for an expenditure of 100 on 
 guano on that field last autumn, I have now reaped an increase 
 produce of 900 bushels of wheat. 
 
 " This tallies very closely with the experience of Mr. Lawes 
 in Hertfordshire, where two cwt. of guano gives an increase of 
 eight bushels of wheat. 
 
 " The land on which the above experiment was made is a strong 
 wheat soil of good quality, thoroughly tile-drained, sown in good 
 order, after a bare fallow, on the 20th of September, and reaped on 
 the 10th of August. The crop suffered no injury (possibly was 
 benefited) by the heavy rains of last winter, which passed off 
 through the soil to the drains as they fell. No manure but guano 
 was applied ; and this was the third application of guano on that 
 field within the last six years. 
 
 " My experience in the south-west of Scotland, with that of 
 Mr. Lawes in the south-east of England, shows that, in the climate 
 of this country, the application of two civt. of Peruvian guano, on 
 a duly-prepared wheat soil, will give an increase of one quarter of 
 ivheat. The conditions, of course, must be observed, that the land 
 is clean, dry, and in a fit state for the reception of the seed, which, 
 if possible, should be sown not later than the 1st of October, and 
 the guano must be applied, not as a top-dressing in spring, but be 
 harrowed in along with the seed. There is no readier means 
 within our knowledge of increasing the wheat crop. We may 
 estimate the clays, or strictly wheat soils of England, to have 
 1,500,000 acres annually under wheat. This class of soil, as is 
 well known, has for some years back been the least hopeful of any. 
 The yield of wheat on such soils, after a clean fallow, probably does
 
 116 LECTURES OX AORICULTUIl.il. CHEMISTRY. 
 
 not exceed, on an average, two-and-a-half quarters an acre. For 
 this all the costs of cultivation must be incurred rent, taxes, seed, 
 and labour; and I believe that, without increasing these necessary 
 costs one farthing, and under the conditions already mentioned, an 
 additional quarter of wheat may be reaped from each acre by an 
 application of two cwt. of Peruvian guano. 
 " This is a matter of vast importance." 
 
 OTHER EXPERIMENTS OF MR. CAIRD. 
 
 "In the centre of a fifty-acre field, one acre was left without 
 manure, all the rest of the field receiving two cwt. of Peruvian 
 guano per acre in autumn, at the time the seed was sown. The 
 produce of the acre undressed has been tested against that of the 
 adjoining acre, which received Peruvian guano, and this is the 
 result : 
 
 One acre, with guano, 32 bushels, 63 Ibs. weight per bushel, 
 
 at 6a. 6d. per 60 Ibs 10 18 4 
 
 One acre, without manure, 25 j bushels, 60 Ibs. weight per 
 
 bushel, at 6s. 6d. per 60 Ibs 8 5 9 
 
 2 12 7 
 Cost of two cwt. of guano in 1853 1 
 
 Profit per acre, besides one-fourth more straw 112 7 
 
 *' The inferiority in the quality of the unmanured wheat, as 
 shown by the weight per bushel, is worthy of notice, as well as the 
 fact that the unmanured wheat was a week later in ripening than 
 the other." 
 
 EXPERIMENTS BY ROBERT MONTEITH, ESQ., OF CARSTAIRS. 
 
 I. OAT CROP, 1843. Part of a field manured with 2G7 Ibs. of 
 guano, at the cost of 31s. per imperial acre, produced, per acre 
 59 bushels.
 
 PRACTICAL EXPERIMENTS WITH GUANO. 117 
 
 Manured with 10 bushels of bone-dust, at the cost of 23s. id. 
 per imperial acre, produced, per acre, 43 bushels. 
 The difference may be stated as follows : 
 
 Cost of Guano 31s. Od. ; produce, 59 bushels, at 2s. 6d. 776 
 Cost of Bones 23s. 4d. ; produce, 43 bushels, at 2s. 6d. 576 
 
 7s. 8d. 200 
 
 Deduct difference of manure 7 8 
 
 Leaving in favour of guano 112 4 
 
 II. HAY CROP, 1843. To part of a field, manured the pre- 
 vious year with farm-yard dung, was given 267 Ibs. of guano per 
 imperial acre, at the cost of 31s., and the extra produce, per acre, 
 was 22 cwt. of hay. 
 
 Which, at 3s. per cwt., is 3 6 
 
 Deduct expense of guano Ill 
 
 Leaving in favour of guano 1 15 per acre. 
 
 EXPERIMENTS BY GEORGE B. OSBORN, ESQ. 
 
 Elburton, near Thorn bury, Gloucestershire, 
 February 28th, 1844. 
 
 GENTLEMEN, 
 
 I BEG to hand you the result of an experiment with guano 
 purchased from you last May. 
 
 The total quantity cropped (to potatoes) was 3 a. 1 r. 18 p., of 
 which 30 perches were manured with 131 Ibs. of guano, at the rate 
 of 6 cwt. 1 qr. per acre ; the remaining portion bad no manure. 
 
 The manured portion produced per acre 85 Sacks. 
 
 The unmanured 52 
 
 Total increase per acre 33 ,,
 
 118 
 
 LECTURES OH AGRICULTURAL CHEMISTRY. 
 
 The profit on one acre, would be 
 
 s. d. 
 
 Increase per acre, 33 sacks at 5s 850 
 
 Cost of guano, carriage and additional labour 4 3 '2 
 
 Clear profit per acre 4 1 10 
 Or, if kept to the present time, a profit per acre of 5 14 10 
 
 The manured part produced by far the best sample ; they were 
 a week at least before the others, and retained, throughout the sea- 
 son, a marked difference. 
 
 The remaining portion of the guano I tried in several ways, and 
 in all found it succeed ; but I made no exact account of its efficacy. 
 I intend trying it on a much larger scale next year, and feel sure 
 it will yield a proportionate return. 
 
 I am, Gentlemen, yours obediently, 
 Messrs. Gibbs, Bright & Co. GEO. B. OSBORN. 
 
 EXPERIMENTS ON GRASS BY ALEX. CAMPBELL, ESQ. 
 The following experiments were made in the year 1843, at the 
 Botanic Gardens, Manchester, by Mr. Alex. Campbell. 
 
 APRIL EXPERIMENT. 
 
 The produce of 1 square yard, on which 1 
 oz. guano mixed with ashes was spread, 
 weighed 3 Ibs. 
 
 The produce of 1 yard, on which 1^ oz. guano 
 mixed with ashes was spread, weighed 3 
 Ibs. 2 oz 
 
 The produce of 1 yard, on which 2 oz. guano 
 mixed with ashes was spread, weighed 
 31bs. Ill oz 
 
 The produce of 1 yard on which 2 5 oz. guano 
 mixed with ashes was spread, weighed 4 
 Ibs. 4 oz 
 
 The produce of 1 yard on which 3 oz. guano 
 mixed with ashes was spread, weighed 4 
 Ibs. 11 oz 
 
 The produce of 1 yard on which 3 5 oz. guano 
 mixed with ashes was spread, weighed 5 
 Ibs. 14 oz 
 
 The produce of 1 yard on which 4 oz. guano 
 mixed with ashes was spread, weigned 4 
 Ibs. 10 oz. . 
 
 KATE PER ACRE. 
 
 PRODUCE, GRAM. MANURE, GUAMO 
 
 Tons. cwt. Ibs. oz. Cwts. Ibs. oz. 
 
 G 9 72 
 
 6 15 50 
 
 78 8 
 5 12 
 
 8 78 12 5 45 
 
 9 3 74 G 84 4 
 
 10 2 63 8 8 11 8 
 
 12 13 99 9 50 12 
 
 9 19 92 10 90
 
 PRACTICAL EXPERIMENTS WITH GUANO. 
 
 119 
 
 These experiments are interesting, as showing a decrease in the 
 production of grass when more than ten cwt. of guano was used 
 per acre. 
 
 EXPERIMENTS UPON THE HAY CROP, BY R. OSBORN, ESQ., 
 BRUNSWICK LODGE, HENBURY. 
 
 Guano per Acre. 
 
 Grass per Perch. 
 
 Grass per Acre. 
 
 Hay per Acre. 
 
 Increase per Acre 
 from use of Guano. 
 
 
 
 Tons. cwt. qrs. Ibs. 
 
 Tons. cwt. qrs. Ibs. 
 
 Tons. cwt. qvs. Ibs. 
 
 2 cwt. 
 
 105 Ib. 
 
 7 10 
 
 2 7 21 
 
 17 3 25 
 
 4 
 
 15o 
 
 11 1 1 20 
 
 3 9 2 18 
 
 2 1 22 
 
 None. 
 
 65 
 
 4 12 3 12 
 
 1 9 24 
 
 
 EXPERIMENTS ON THE APPLICATION OF GUANO AND OTHER 
 MANURES, IN THE DUKE OF DEVONSHIRE'S PARK AT STO- 
 VER, NEAR NEWTON ABBOT, DEVON. BY E. S. BEARNE. 
 
 No. I. Report of an experiment to test the comparative 
 efficiency of five different kinds of artificial manure in improving 
 pond mud, the experiment being made on an acre of inferior pas- 
 ture land in Stover Park, in the years 1847, 1848, and 1849. The 
 land on which the experiment was conducted is of uniform quality, 
 the land being of a light sandy loam a few inches in depth, incum- 
 bent on a stratum of white clay. The land underwent a thorough 
 drainage in 1844, previous to which it would not produce a rent 
 of more than 5s. per acre. No manures were applied to the land 
 in 1848 or 1849. The object sought to be attained by extending 
 the experiment over a period of three years, is to test the durability 
 of the different manures.
 
 120 
 
 LECTURES ON AGRICULTURAL CHEMISTRY. 
 
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 PRACTICAL EXPERIMENTS WITH GUANO. 121 
 
 EXTRACT FROM A LETTER FROM J. M. PAINE, ESQ., 
 OF FARNHAM. 
 
 (From the Gardener's Chronicle.) 
 
 "As regards the application of ammonia to the cereal crops, I 
 repeat that it is of no importance in what form it is given to the 
 soil ; therefore apply that which gives the largest per centage of 
 ammonia for your money. At the present time Peruvian Guano 
 (not adulterated rubbish), giving seventeen or eighteen per cent, 
 of ammonia, is the cheapest source of supply. Last year, after a 
 crop of pulled-off swedes, I put on three cwt. of Peruvian guano, 
 mixed with the same quantity of phosphoric marl, per acre ; and 
 the result, as I have before stated, was a trifle over eight quarters 
 of barley per acre ; and in 1848, on a field of barley, after swedes 
 fed off' by sheep, and topdressed, when about six inches high, with 
 eighty-four Ibs. per acre of the sulphate of ammonia, mixed with 
 two cwt. of phosphoric marl,* we omitted a few lands in different 
 parts of the field, and we considered that we obtained from twelve 
 to sixteen bushels more barley per acre on the top-manured por- 
 tions. Last year my oat crop averaged full twelve quarters per 
 acre ; we have now just finished cutting this year's crop, and we 
 expect to obtain an average of fourteen quarters. This crop is 
 after turnips and swedes, about half of which were drawn from the 
 field. When the oats were sown, four cwt. per acre of the guano 
 and soot mixture with the fossil powder was applied. The land 
 is naturally a poor gravelly clay, resting upon chalk. A neighbour 
 of mine, upon a similar soil, after trenching it, applied six cwt. per 
 acre of Peruvian guano, and his crop is about equal to my own ; 
 while another neighbour, in an adjoining field to my oats, who farms 
 in the old fashioned way, will not grow much above a fifth of either 
 
 * The first discovery of the presence of phosphoric acid in the Farnham 
 Marls was made by me in the year 1847 ; but no notice was taken of this fact 
 in the paper which subsequently appeared on this subject in the 9th volume of 
 the Journal of the Royal Agricultural Society, although the writers received 
 the original information directly from myself. J. C. N.
 
 122 LECTURES OW AGRICULTURAL CIIKMISTRY. 
 
 
 
 of our crops. I ought, perhaps, to add that we do not obtain u crop 
 of weeds as well as corn, it being our object to have no trouble in 
 cleansing our turnip fallows. If I had pulled off all my turnips, I 
 should have doubled my artificial manuring for my oats. In ma- 
 nuring ammoniacally for wheat, if the soil were a clay or stiff loam, 
 I would apply the whole dose in the autumn ; if gravelly or chalky, 
 half at the time of sowing, and the remainder early in March. In 
 conclusion, when we have weak spots of corn in my fields, we mend 
 them with guano in the spring." 
 
 OBSERVATIONS ON THE USE OF GUANO FOR GRASS AM) 
 HAY. BY PROFESSOR ANDERSON, GLASGOW. 
 
 Transactions of the Hiyhland and Agricultural Society, March, 1856. 
 
 The superiority of guano is particularly evident, both from 
 Mr. Porter's and Mr. M'Laren's experiments the former obtaining 
 by its use a produce exceeding that from nitrate of soda by almost 
 exactly a fifth, and the latter by nearly a sixth. Mr. M'Laren's 
 experiments have the additional importance of showing the 
 greater slowness and permanence of action of guano, which appears 
 to have produced upon the second crop of hay a considerably 
 greater effect than it did upon the first. The conclusion to which 
 we are thus brought is in perfect accordance with theory, for it is 
 to be observed that the manures employed were taken so as to 
 supply the same quantity of nitrogen, irrespective of their other 
 constituents ; and so, as their effect is dependent upon that sub- 
 stance alone, it seems to be immaterial whether it be in the state 
 of ammonia or nitric acid. But Peruvian guano produces a greater 
 manurial effect, because it supplies phosphates and alkaline salts, 
 in addition to nitrogen; and hence its composition justifies the title 
 of a "TRUE MANURE," applied to it by Mr. M'Laren.
 
 DETERMINATION OF THE VAT.TTE OF MANURES. 123 
 
 APPROXIMATE ESTIMATION OF THE VALUE OF 
 
 MANURES. 
 
 IN consequence of the variation in the composition of manure, 
 and the constant adulterations practised by unprincipled dealers, 
 it is a matter of considerable importance to the farmer to be able 
 in an easy manner to obtain an approximative value of any manure 
 which he may have subjected to analysis ; and we subjoin a mode 
 of valuation, the use of which will at least save him from the gross 
 imposition to which he is at present subjected. The substances 
 which analysis and practice have proved to be most efficient as ma- 
 nuring principles are phosphates, and nitrogen in any of its forms. 
 
 A few isolated experiments prove potash to be of some value 
 to one or two crops ; but, as this substance can readily be bought 
 in a state of tolerable purity as sulphate or muriate of potash, 
 and as it is not generally found in compounded manures, we shall 
 not give this any agricultural value, further than as comprised 
 under the term of alkaline salts. 
 
 Silica, under any of its forms, has not yet been proved to have 
 any agricultural value ; and carbonate of lime (chalk) is in most 
 instances a serious detriment to a manure, though useful on the 
 large scale, when used per acre by tons at a time. 
 
 From a careful comparison of numerous analyses of manure 
 with the value of the substances therein contained, we have been 
 led to adopt the following prices as giving the nearest approxima- 
 tive value of the several manuring matters : 
 
 MULTIPLIERS OP VAMJE. 
 
 Nitrogen 74 per Ton. 
 
 Ammonia ..... 60 
 
 Phosphate of lime ... 8 ,, 
 
 Phosphate of Lime made soluble 24 
 
 Organic matter .... 1 ,, 
 
 Alkaline salts .... 1 
 
 Sulphate of lime (gypsum) . 1 
 
 Silica ..... No value. 
 
 Carbonate of lime . . No value.
 
 124 LECTURES ON AGRICUI.TURAT, CHEMISTRY. 
 
 The following mode of calculation has been adopted by me for 
 many years, and is exceedingly simple, as we only require the 
 analysis of the sample to enable us to arrive at its worth in a very 
 few figures: 
 
 RULE FOR CALCULATING THE VALUE OF MANURES. 
 
 Consider the analysis to represent the components of one hun- 
 dred tons. Multiply the respective amounts of each ingredient by 
 its price per ton in the preceding table, add up the several products, 
 and the sum will represent the value of one hundred tons. Divide 
 this amount by one hundred, and the quotient will be the price per 
 ton. 
 
 The decimals in the analysis below 0.5 may be disregarded, and 
 those above that amount reckoned as an additional unit. Thus, in 
 the second example, the organic matter, instead of 21.68, may be 
 read 22 ; and the phosphate of lime, instead of 44.35, may be 
 called 44. 
 
 EXAMPLES. 
 I. VALUATION OF AN AVERAGE SAMPLE OF PERUVIAN GUANO. 
 
 Value per Ton. Total. 
 
 Moisture 15-10 
 
 Organic Matter .... 51-27 X 1 = 51 
 
 Silica 2-20 
 
 Phosphate of Lime . . . 22-13 X 8 = 176 
 
 Phosphoric Acid . .' . 3-23 
 
 = Phosphate of Lime (made Soluble) 7-00 x 24 168 
 
 Alkaline Salts, &c. '". . . 6-07 X 1 6 
 
 100-00 
 
 Nitrogen (equal to) ... 13-54 per cent. 
 
 Ammonia 16-42 x 60 = 960 
 
 1,00)13,61 
 
 20 
 Value 13, 12a. per ton. 
 
 12-20
 
 DETERMINATION 'OF THE VALUE OF MANURES. 
 
 125 
 
 II. VALUATION OF SAMPLE OF BOLIVIAN GUANO. 
 
 Value per Ton. Total, 
 
 : 1 = 22 
 8 = 352 
 
 Moisture . . - . . . 
 Organic Matter ..... 
 
 Silica - . 
 
 Phosphate of Lime .... 
 Phosphoric Acid ..... 
 = Neutral Phosphate (made Soluble) 7-15 
 Alkaline Salts . . . \ 
 
 13-85 
 21-68 
 
 2-70 
 44-35 
 
 3-30 
 
 14-12 
 100-00 
 
 Ammonia 
 
 Value 7, 19s. per ton. 
 
 24 = 168 
 1 = 14 
 
 4-02 X 60 = 240 
 
 1,00)7,96 
 20 
 
 19.20 
 
 III. VALUATION OF A GOOD SAMPLE OF SUPERPHOSPHATE OF LIME. 
 
 Value per Ton. Total. 
 Moisture . . , 
 Organic Matter . . 
 Silica . . . '-.'-. 
 Soluble Phosphate 
 
 = Neutral Phosphate (made Soluble) 16-00 
 Insoluble Phosphate . . '.'. 
 Hydrated Sulphate of Lime 
 
 Ammonia 
 
 Value 6, 18s. per ton. 
 
 IV. VALUATION OF A BAD SAMPLE OF SUPERPHOSPHATE OF LIME. 
 
 Value per Ton. Total. 
 
 19-82 
 
 
 
 
 20-72 
 
 X 
 
 1 
 
 = 21 
 
 2-80 
 
 
 
 
 10-25 
 
 
 
 
 
 X 
 
 24 
 
 = 384 
 
 16-60 
 
 X 
 
 8 
 
 = 136 
 
 29-81 
 
 X 
 
 1 
 
 = 30 
 
 100-00 
 
 
 
 
 2-00 
 
 X 
 
 60 
 
 = 120 
 
 
 
 1,00)6,91 
 
 
 
 
 20 
 
 
 
 
 18-20 
 
 Moisture 
 
 17-90 
 
 
 
 Organic Matter . . , . . 
 
 14-00 x 
 
 1 
 
 = 14 
 
 Silica . . . ... 
 
 29-10 
 
 
 
 Oxide of Iron, &c. 
 
 8-62 
 
 
 
 Soluble Phosphate .' 
 
 3-24 
 
 
 
 = Neutral Phosphate (made Soluble) 
 Insoluble Phosphate . . 
 
 5-05 X 
 3-85 x 
 
 ' 24 
 8 
 
 = 120 
 
 = 32 
 
 Hydrated Sulphate of Lime . , 
 
 . : . 23-29 x 
 
 1 
 
 = 23 
 
 
 100-00 
 
 
 
 Ammonia . . . " . ^ . 
 
 0-50 x 
 
 60 
 
 = 30 
 
 1,00)2,19 
 
 
 
 
 20 
 
 Value 2, 4s. per ton. 
 
 3-80
 
 126 I I.CTURES OX AGRICULTURAL CHEMISTRY. 
 
 V. VALUATION OF ADULTERATED GUANO,* SOLD AS GENUINE 
 
 PERUVIAN. 
 
 Value per Ton. Total. 
 
 Moisture . . . . . 5-40 
 
 Organic mutter, &o. . ; . 20-55 x 1 = 21 
 
 Sand ..... 49-30 
 
 Oxide of iron and alumina . 5-46 
 
 Phosphate of lime . . i 16-25 X 8 .128 
 
 Carbonate of lime, &c. . . 3-04 
 
 100-00 
 
 Nitrogen (equal to) . . . 4-65 
 
 Ammonia .' . . 5-64 X 60 = 360 
 
 Value 5 per Ton. 5,09 
 
 * Often sold as Peruvian guano a pound or so under the market price, to 
 farmers who are in want of A BARGAIN. 
 
 VI. VALUATION OP A SUBSTANCE LATELY INTRODUCED INTO 
 COMMERCE, CALLED " MEXICAN GUANO." 
 
 Value per Ton. Total. 
 
 Moisture 3-24 
 
 Organic matter, &c. . . 13-56 X 1 14 
 
 Silica . . ... . 0-60 
 
 Phosphate of lime . . . 25 60 X 8 208 
 
 Carbonate of lime . . . 46-14 
 
 Sulphate of lime, &c. . . 10-86 X 1 11 
 
 100-00 
 
 Nitrogen (equal to) 0-21 
 
 Ammonia 0-26 x 60 = 15 
 
 2,48 
 20 
 
 Value 2, 9s. per Ton. f 9-60 
 
 t This value is, however, practically lessened by the large quantity of car- 
 bonate of lime contained in the sample. Yet this substance has actually been 
 bought by farmers as guano at from 8 to 9 per ton. 
 
 The foregoing examples show how very closely the rule brings 
 out all the actual value of the various samples. It is necessary, 
 however,, to remember that circumstances might possibly arise in 
 the course of time, which would render some alteration necessary 
 in the^amounts of our multipliers of value. At the present period, 
 however, they are sufficiently true for every practical purpose.
 
 ON NITRIFICATIOK. 127 
 
 ON NITRIFICATION. 
 
 LETTER TO THE LATE PH. PUSEY, ESQ. 
 
 (Journal of the Royal Agricultural Society, vol. xiv., page 391.) 
 
 DEAR SIR, At your request I subjoin a few observations on the conditions 
 required for the formation of nitrates. 
 
 For some years, in my lectures, I have endeavoured to direct the attention 
 of the farmer to the artificial formation of nitre, having felt somewhat sur- 
 prised that its importance has hitherto been so generally overlooked. 
 
 I shall at present content myself with a brief explanation of the conditions 
 under which NITRATES are formed. Whenever animal or vegetable matter 
 gaseous, liquid, or solid containing nitrogen, comes into contact with mild 
 calcareous or alkaline earths, the mixture being moist, and so porous that the 
 air can easily penetrate, after some time the nitrogen, under certain conditions 
 of temperature, is acted upon by the atmosphere, is oxidized, and is converted 
 into nitric acid, which at once unites with the calcareous or alkaline bases 
 present in the mixture. 
 
 The temperature most suitable is from 58 to 68 Fahr., and the action 
 ceases at 32 Fahr., the freezing point. 
 
 The instances of the oxidation of gaseous nitrogenous bodies are very com- 
 mon. The mortar of almost all old buildings, in any situation, contains a 
 greater or less amount of nitrate of lime, the nitric acid of which is produced 
 by the oxidation of ammonia, absorbed by the mortar from the atmosphere. 
 Another example is that furnished by an experiment of a French philosopher, 
 who suspended a piece of moistened and well-washed chalk over a basin of 
 putrifying blood, and who, after the lapse of some time, detected easily the 
 presence of nitric acid in the chalk. 
 
 The oxidation of liquid nitrogenous compounds is also of ordinary occurrence. 
 The urine of any animal mixed with calcareous or earthy matter readily fur- 
 nishes nitrates by oxidation ; and even the urinary deposits of animals on 
 pastures in summer give rise to the formation of nitrates. The walls of stables 
 and cowhouses, which by absorption have been moistened with urine, often 
 give on their surfaces efflorescences of nitre. 
 
 The conversion into nitric acid of the nitrogen of solid animal'or vegetable 
 matters, constantly occurs when these bodies are in contact with earthy calca- 
 reous matters. Even in the absence of calcareous substances, nitric acid is 
 formed in such common dung-heaps as consist merely of decomposing animal 
 and vegetable matter; for one part of the ammonia produced by ordinary 
 decomposition acts as the alkaline base to another portion, which by oxidation 
 is converted into nitric acid. Nitrate of ammonia may always be found in 
 dung-heaps. Nitrates are also present in all shallow wells adjacent to church- 
 yards, and in those which derive their liquid supplies from strata into which 
 cesspools empty themselves. 
 
 The proper conditions for the formation of nitrates are always to be found 
 in well-drained and well-manured fields, particularly when they contain calca- 
 reous matter. One of the great uses of liming is to furnish the alkaline matter 
 where it is deficient. In our laboratories we have examined a great number of 
 soils, nnd in almost every instance have detected the presence of nitre.
 
 128 LECTURES OT* AGRICULTURAL CHEMISTRY. 
 
 In my opinion, a proper knowledge of the mode of forming nitre beds would 
 be of considerable importance to the farmer ; for by their use not only would 
 lie be able to conserve the ammonia of his manure when he had more of the 
 latter than he could at once apply to the land, but by using the liquid manure 
 from the tanks, the necessary moisture would be given to the heap ; and whilst 
 the aqueous particles, so expensive to carry, would gradually evaporate, the 
 valuable matters of the liquid would be retained in the compost. 
 
 The mode of making artificial nitre-beds has been shortly described in my 
 lecture to which you refer. It is exceedingly simple. A layer of calcareous 
 matter forms the base of the heap, and layers of horse-dung, cow-dung, carrion, 
 or other similar matters, alternating with layers of marl, mortar, or spent lime, 
 will constitute the nitre-bed. The mixture should always be kept moist with 
 urine, or urine and water; but too much water, as from rain, would be injurioM, 
 nnd the heap ought therefore to be kept under cover. The compost should 
 lie as loosely as possible together, that the air may be easily able to permeate 
 the mass. The heap should be thoroughly incorporated, and lightly turned 
 over once in two or three months. In from six to nine months it will be ready 
 for the farmer's use. Quick lime ought not to be used in making nitre-beds, as 
 its first and most powerful action is to drive off the ammonia from the manure. 
 
 It must be understood that, by making mixtures calculated to give rise to 
 the artificial production of nitrates, we have a means of preventing the loss of 
 ammonia which takes place in a common dung-heap ; and that, under ordinary 
 circumstances, manures containing either nitrates or ammonia, without any 
 important amount of other substances, are valuable exactly in proportion to the 
 amount of nitrogen they contain. It may be necessary to mention, that in 
 soils and dung-heaps the nitric aoid produced by oxidation of ammonia is re- 
 converted into ammonia when putrefaction is taking place, and acceta of air if 
 prevented. 
 
 In conclusion, I may mention that I have analysed a portion of a large nitre- 
 bed of about forty tons, which was (about ten months since) made on the pre- 
 mises attached to the College at Kennington. Though the heap has been 
 exposed to all the rains of the season, it was found that one pound weight of 
 the compost contained twenty-one grains of nitric acid, which is equivalent to 
 thirty-four grains of saltpetre. This is an amount much below what we should 
 have found had we had the heap under cover. 
 
 I am, ray dear Sir, yours very truly, 
 
 J. C. NESBIT. 
 
 College of Agriculture and Chemistry, 
 Kennington, Dec. 13, 1853. 
 
 Henry Viz*telljr, Printer and Engrarer, Cough Square, Flel Street, London.
 
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