 Section 15 of Familiar Letters on Chemistry this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org recording by Gary Gilbert 2007 familiar letters on chemistry by Justice Libig letter number 15 my dear sir you are now acquainted with my opinions respecting the effects of the application of mineral agents to our cultivated fields and also the rationale of the influence of the various kinds of manures you will therefore now readily understand what I have to say of the sources whence the carbon and nitrogen indispensable to the growth of plants are derived the growth of forests and the produce of meadows demonstrate that an inexhaustible supply of carbon is furnished for vegetation by the carbonic acid of the atmosphere we obtain from an equal surface of forest or meadowland where the necessary mineral elements of the soil are present in a suitable state and to which no carbonaceous matter whatever is furnished in manures an amount of carbon in the shape of wood and hay quite equal and oftentimes more than is produced by our fields in grain roots and straw upon which abundance of manure has been heaped it is perfectly obvious that the atmosphere must furnish to our cultivated fields as much carbonic acid as it does to an equal surface of forest or meadow and that the carbon of this carbonic acid is assimilated or may be assimilated by the plants growing there provided the conditions essential to its assimilation and becoming a constituent element of vegetables exists in the soil of these fields in many tropical countries the produce of the land in grain or roots during the whole year depends upon one rain in the spring if this rain is deficient in quantity or altogether wanting the expectation of an abundant harvest is diminished or destroyed now it cannot be the water merely which produces this enlivening and fertilizing effect observed and which lasts for weeks and months the plant receives by means of this water at the time of its first development the alkalis alkaliners and phosphates necessary to its organization if these elements which are necessary previous to its assimilation of atmospheric nourishment be absent its growth is retarded in fact the development of a plant is in a direct ratio to the amount of matter it takes up from the soil if therefore a soil is deficient in these mineral constituents required by plants they will not flourish even with an abundant supply of water the produce of carbon on a meadow or an equal surface of forest land is independent of a supply of carbonaceous manure but it depends upon the presence of certain elements of the soil which in themselves contain no carbon together with the existence of conditions under which their assimilation by plants can be affected we increase the produce of our cultivated fields in carbon by a supply of lime ashes and moral substances which cannot furnish carbon to the plants and yet it is indisputable being founded upon abundant experience that in these substances we furnish to the fields elements which greatly increase the bulk of their produce and consequently the amount of carbon if we admit these facts to be established we can no longer doubt that a deficient produce of carbon or in other words the bareness of a field does not depend upon carbonic acid because we are able to increase the produce to a certain degree by a supply of substances which do not contain any carbon the same source when the meadow and the forest are furnished with carbon is also open to our cultivated plants the great object of agriculture therefore is to discover the means best apted to enable these plants to assimilate the carbon of the atmosphere which exists in it as carbonic acid in furnishing plants therefore with mineral elements we give them the power to approximate carbon from a source which is inexhaustible wilson the absence of these elements the most abundant supply of carbonic acid or of decaying vegetable matter would not increase the produce of a field with an adequate and equal supply of these essential mineral constituents in the soil the amount of carbonic acid absorbed by a plant from the atmosphere in a given time is limited by the quantity which is brought into contact with its organs of absorption the withdrawal of carbonic acid from the atmosphere by the vegetable organism takes place chiefly through its leaves this absorption requires the contact of the carbonic acid with their surface or with the parts of the plant by which it is absorbed the quantity of carbonic acid absorbed in a given time is in direct proportion to the surface of the leaves and the amount of carbonic acid contained in the air that is two plants of the same kind and the same extent of surface absorption in equal times and under equal conditions absorb one and the same amount of carbon in an atmosphere containing a double portion of carbonic acid a plant absorbs under the same condition twice the quantity of carbon bozen galt observed that the leaves of the vine enclosed in a vessel withdrew all the carbonic acid from a current of air which was passed through it however create its velocity dumas lecan page 23 if therefore we supply double the quantity of carbonic acid to one plant the extent of the surface of which is only half that of another living in ordinary atmospheric air the former will obtain and approximate as much carbon as the latter hence results the effect of humus and all decaying organic substances upon vegetation if we suppose all the conditions for the absorption of carbonic acid present a young plant will increase in mass in a limited time only in proportion to its absorbing surface but if we create in the soil a new source of carbonic acid by decaying vegetable substances the roots absorb in the same time three times as much carbonic acid from the soil as the leaves derive from the atmosphere the plant will increase in weight fourfold this fourfold increase extends to the leaves buds stalks etc and in the increased extent of the surface the plant acquires an increased power of absorbing nourishment from the air which continues in action far beyond the time when its derivation of carbonic acid through the roots ceases humus as a source of carbonic acid in cultivated lands is not only useful as a means of increasing the quantity of carbon an effect which in most cases may be indifferent for agricultural purposes but the mass of the plant having increased rapidly in a short time space is obtained for the assimilation of the elements of the soil necessary for the formation of new leaves and branches water evaporates incessantly from the surface of the young plant its quantity is in direct proportion to the temperature and the extent of the surface the numerous radical fibrule replace like so many pumps the evaporated water and so long as the soil is moist or penetrated with water the indispensable elements of the soil dissolved in the water are supplied to the plant the water absorbed by the plant evaporating in an area formed state leaves the saline and other mineral constituents within it the relative proportion of these elements taken up by a plant is greater the more extensive the surface and more abundant the supply of water where these are limited the plant soon reaches its full growth while if their supply is continued a greater amount of elements necessary to enable it to appropriate atmospheric nourishment being obtained its development proceeds much further the quantity or mass of seed produced will correspond to the quantity of mineral constituents present in the plant that plant therefore containing the most alkaline phosphates and earthy salts will produce more or a greater weight of seeds than another which in equal time has absorbed less of them we consequently observe in a hot summer with a further supply of mineral ingredients from the soil ceases through want of water that the height and strength of plants as well as the development of their seeds are in direct proportion to its absorption of the elementary parts of the soil in the preceding epics of its growth the fertility of the year depends in general upon the temperature and the moisture or dryness of the spring if all the conditions necessary to the assimilation of the atmospheric nourishment be secured to our cultivated plants the action of humus then as we have explained it above is chiefly of value in gaining time in agriculture this must ever be taken into account and in this respect humus is of importance in favoring the growth of vegetables cabbages etc but the cerellella and plants grown for their roots meet on our fields in the remains of the preceding crop with a quantity of decaying vegetable substances corresponding to their contents of mineral nutriment from the soil and consequently with a quantity of carbonic acid adequate to their accelerated development in the spring a further supply of carbonic acid therefore would be quite useless without a corresponding increase of mineral ingredients from a morgan of good meadowland 2,500 pounds weight of hay according to the best agriculturalists are obtained on an average this amount is furnished without any supply of organic substances without manure containing carbon or nitrogen by irrigation and the application of ashes or gypsum double that amount may be grown but assuming 2,500 pounds weight of hay to be the maximum we may calculate the amount of carbon and nitrogen derived from the atmosphere by the plants of the meadow according to elementary analysis hay dried at a temperature of 100 degrees rumor contains 45.8 of carbon and one and one half percent of nitrogen 14 percent of water retained by the hay dried at common temperatures is driven off at 100 degrees 2,500 pounds weight of hay therefore corresponds to 2,150 pounds dried at 100 degrees this shows us that 984 pounds of carbon and 32.2 pounds weight of nitrogen have been obtained in the produce of one morgan of meadowland suppose that this nitrogen has been absorbed by the plants in the form of ammonia the atmosphere contains 39.1 pounds weight of ammonia to every 3,640 pounds weight of carbonic acid equals 984 carbon or 27 percent or in other words to every 1,000 pounds weight of carbonic acid 10.7 pounds of ammonia that is to about 100,000th the weight of the air or 160,000th of its volume for every 100 parts of carbonic acid absorbed by the surface of the leaves the plant receives from the atmosphere somewhat more than one part of ammonia with every 1,000 pounds of carbon we obtain from a meadow 32.7 pounds of nitrogen from cultivated fields in wheat 21 and one half pounds of nitrogen oats 22.3 pounds of nitrogen rye 15.2 pounds of nitrogen potatoes 34.1 pounds of nitrogen beetroot 39.1 pounds of nitrogen clover 44 pounds of nitrogen peas 62 pounds of nitrogen boson galt obtained from his farm at betelbron in alfons in five years the shape of potatoes wheat clover turnips and oats 8383 of carbon and 250.7 nitrogen in the following five years as beetroot wheat clover turnips oats and rye 8192 of carbon and 284.2 of nitrogen in a further course of six years potatoes wheat clover turnips peas and rye 10,949 of carbon 356.6 of nitrogen in 16 years 27,424 carbon 858 and one half nitrogen which gives us for every 1,000 carbon 31.3 nitrogen from these interesting and unquestionable facts we may deduce some conclusions of the highest importance in their application to agriculture one we observe that the relative proportions of carbon and nitrogen stand in a field relation to the surface of the leaves those plants in which all the nitrogen may be said to be concentrated in the seeds as in cereala contain on the whole less nitrogen than the legumes plants peas and clover two the produce of nitrogen on a meadow which receives no nitrogenized manure is greater than that of a field of wheat which has been manured three the produce of nitrogen in clover and peas which agriculturalists will acknowledge require no nitrogenized manure is far greater than that of a potato or turnip field which is abundantly supplied with such manures lastly and this is the most curious deduction to be derived from the above facts if we plant potatoes wheat turnips peas and clover plants containing potash lime and silics upon the same land three times manured we gain in 16 years for a given quantity of carbon the same proportion of nitrogen which we receive from a meadow which has received no nitrogenized manure on a Morgan of meadow land we obtain in plants containing silics lime and potash 984 carbon 32.2 nitrogen on a Morgan of cultivated land in an average of 16 years the plants containing the same mineral elements silics lime and potash 857 carbon 26.8 nitrogen if we add the carbon and nitrogen of the leaves of the beetroot and the stalk and leaves of the potato which have not been taken into account it still remains evident that the cultivated fields notwithstanding the supply of carbonaceous and nitrogenized manures produce no more carbon and nitrogen than an equal surface of meadowland supplied only with mineral elements what then is the rationale of the effective manure of the solid and fluid experiments of animals this question can now be satisfactorily answered that effect is the restoration of the elementary constituents of the soil which have been gradually drawn up from it in the shape of grain and cattle if the land I am speaking of had not been manure during those 16 years not more than one half or perhaps than one third part of the carbon and nitrogen would have been produced we owe it to the animal experiments that it equaled in production the meadowland and thus because they restored the mineral ingredients of the soil removed from the crops all that the supply of manure accomplished was to prevent the land from becoming poorer in these then the meadow which produces 2500 pounds of hay we withdraw from the meadow in this way hay is large in amount of mineral substances as we do in one harvest of grain and we know that the fertility of the meadow is just as dependent upon the restoration of these ingredients to its soil as the cultivated land is upon manures two meadows of equal surface containing unequal quantities of inorganic elements of nourishment other conditions being equal are very unequally fertile that which possesses most furnished most hay if we do not restore to a meadow the withdrawn elements its fertility decreases but its fertility remains unimpaired when a due supply of animal excrement fluid and solid and it not only remains the same but may be increased by a supply of mineral substances alone such as remain after the combustion of lignacious plants and other vegetables namely ashes ashes represent the whole nourishment which vegetables receive from the soil by furnishing them in sufficient quantities to our meadows we give the plants growing on them the power of condensing and absorbing carbon and nitrogen by their surface may not the effect of the solid and fluid excrements which are the ashes of plants and grains which have undergone combustion in the bodies of animals and of man be dependent upon in the same cause should not the fertility resulting from their application be altogether independent of the ammonia they contain would not their effect be precisely the same in promoting the fertility of cultivated plants if we had evaporated the urine and dried and burned the solid excrements surely the cereella and leguminous plants which we cultivate must derive their carbon and nitrogen from the same source whence the gramea and leguminous plants of the meadow obtain them no doubt can be entertained of their capability to do so in virginia upon the lowest calculation 22 pounds weight of nitrogen were taken on the average yearly from every Morgan of the wheat fields this would amount in 100 years to 2200 pounds weight if this were derived from the soil every Morgan of it must have contained the equivalent of 110,000 pound weight of animal excrements assuming the ladder when dried at the temperature of boiling water to contain 2% in Hungary as I remarked in a former letter tobacco and wheat have been grown upon the same field for centuries without any supply of nitrogenized manure is it possible that the nitrogen essential to and entering into the composition of these crops could have been drawn from the soil every year renews the foliage and fruits of our forests of beach oak and chestnuts the leaves the acorns the chestnuts are rich in nitrogen so are coconuts breadfruit and other tropical productions this nitrogen is not supplied by man can it indeed be derived from any other source than the atmosphere in whatever form the nitrogen supplied to plants may be contained in the atmosphere in whatever state it may be when absorbed from the atmosphere it must have been derived did not the fields of virginia receive their nitrogen from the same source as the wild plants is the supply of nitrogen in the excrement of animals quite a matter of indifference or do we receive back from our fields a quantity of the elements of blood corresponding to this supply the researchers of buzzing galt have solved this problem in the most satisfactory manner if in his grand experiments the manure which he gave to his fields was in the same state in other words dried at 110 degrees in a vacuum as it was when analyzed these fields received in 16 years 1300 pounds of nitrogen but we know that by drying all the nitrogen escapes which is contained in solid animal excrements as volatile carbonate of ammonia in this calculation the nitrogen of the urine which by decomposition is converted into carbonate of ammonia has not been included if we suppose it amounted to half as much as that in the dried excrements this would make the quantity of nitrogen supplied to the fields 1,950 pounds in 10 years however as we have seen only 1,517 pounds of nitrogen was contained in their produce of grain straw roots etc that is far less than was supplied in the manure and in the same period the same extent of surface of good meadowland one hectic or equals one hessian morgan which received no nitrogen in manure 2062 pounds of nitrogen it is well known that in egypt from the deficiency of wood the excrement of animals is dried and forms the principal fuel and that the nitrogen from the soot of this excrement was for many centuries imported into europe in the form of sal ammonia until a method of manufacturing this substance was discovered at the end of the last century by gravenhorst of brunswick the fields in the delta of the Nile are supplied with no other animal manures than the ashes of the burnt excrements and that they have been proverbially fertile from a period earlier than the first dawn of history and that fertility continues to the present day as admirable as it was in the earliest times these fields receive every year from the inundation of the Nile a new soil in its mud deposited over their surface rich in those mineral elements which have been withdrawn by the crops of the previous harvest the mud of the Nile contains as little nitrogen as the mud derived from the alps of switzerland which fertilizes our fields after the inundations of the rime if this fertilized mud owed its property to nitrogenized matters what enormous beds of animals and vegetables excavate and remains ought to exist in the mountains of africa in heights extending beyond the limits of perpetual snow where no bird no animal finds food from the absence of all vegetation abundant evidence to support of the important truth we are discussing may be derived from other well-known facts thus the trade of holland and cheese may be abducted in proof and illustration thereof we know that cheese is derived from the plants which serve as food for cows the meadowlands of holland drive the nitrogen of cheese from the same source as with us i.e. the atmosphere the milch cows of holland remain day and night on the grazing grounds and therefore in their fluid and solid excrement return directly to the soil all the salts and earthy elements of their food a very insignificant quantity only is exported in cheese the fertility of these meadows can therefore be as little impaired as our own fields to which we restore all the elements of the soil as manure which have been withdrawn in the crops the only difference is in holland they remain on the field will we collect them at home and carry them from time to time to the fields the nitrogen of the fluid and solid excrement of cows is derived from the meadow plants which received it from the atmosphere the nitrogen of the cheese also must be drawn from the same source the meadows of holland have in the laps of centuries produced millions of hundreds weights of cheese thousands of hundred weights are annually exported and yet the productiveness of the meadows is in no way diminished although they never receive more nitrogen than they originally contained nothing can be more certain than the fact that an exportation of nitrogenized products does not exhaust the fertility of a country in as much as it is not the soil but the atmosphere which furnishes its vegetation with nitrogen it follows consequently that we cannot increase the fertility of our fields by simply of nitrogenized manure or by salts of ammonia but rather that their produce increases or diminishes in direct ratio with the supply of mineral elements capable of assimilation the formulation of the constituent elements of blood that is of the nitrogenized principles in our cultivated plants depends upon the presence of inorganic matters in the soil without which no nitrogen can be assimilated even when there is a most abundant supply the ammonia contained in animal excrement exercises a favorable effect in as much as it is accompanied by the other substances necessary to accomplish this transition into the elements of the blood if we supply ammonia associated with all the conditions necessary to its assimilation it ministers to the nourishment of the plants but if this artificial supply is not given they can derive all the needed nitrogen from the atmosphere a source every loss from which is restored by the decomposition of the bodies of dead animals and the decay of plants ammonia certainly favors and accelerates the growth of plants in all soils wherein all the conditions of its assimilation are united but it is all together without effect as respects the production of the elements of blood where any of these conditions are wanting we can suppose that asparagin the active constituent of asparagus the musilaginous root of the marshmallow the nitrogenized and sulfurous ingredients of mustard seeds and of all cruciferous plants may originate without the aid of the mineral elements of the soil but at the principle of those vegetables which serve as food could be generated without the cooperation of the mineral elements of blood without potash soda phosphate of soda phosphate of lime they would be useless to us and to herbivacious animals as food they would not fulfill the purpose for which the wisdom of the creator has designed them in the absence of alkalis and phosphates no blood no milk no muscular fiber can be formed without phosphate of lime our horses sheep and cattle would be without bones in the urine and in the solid excrement of animals we carry ammonia and consequently nitrogen to our cultivated plants and this nitrogen is accompanied by all the mineral elements of food exactly in the same proportions in which both are contained in the plants which served as food to the animals or what is the same in those proportions in which both can serve as nourishment to a new generation of plants to which both are essential the effect of an artificial supply of ammonia as a source of nitrogen is therefore precisely analogous to that of humus as a source of carbonic acid it is limited to a gain of time that is it accelerates the development of plants this is of great importance and should always be taken into account in gardening especially in the treatment of the kitchen garden and as much as possible in agriculture on a large scale where the time occupied in the growth of the plants cultivated is of importance when we have exactly ascertained the quantity of ash left after the combustion of cultivated plants which have grown upon all varieties of soil and have obtained correct analysis of these ashes we shall learn with certainty which of the constituent elements of the plants are consistent and which are changeable and we shall arrive at an exact knowledge of the sum of all the ingredients we withdraw from the soil in different crops with this knowledge the farmer will be able to keep an exact record of the produce of his fields and harvest like the account book of a well-regulated manufacturing and then by a simple calculation he can determine precisely the substances he must supply to each field and the quantity of these in order to restore their fertility he will be able to express in pounds weight how much of this or that element must be given in order to augment its fertility for any given kind of plants these researches and experiments are the great des stratum of the present time to the united efforts of the chemists of all countries we may confidently look for a solution of these great questions and by the aid of enlightened agriculturalists we shall arrive at a rational system of gardening horticulture and agriculture applicable to every country and in all kinds of soil and which will be based upon the immutable foundation of observed facts and philosophical induction end of section 15 section 16 of familiar letters on chemistry by justus libig this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to find out how to volunteer please contact LibriVox.org recorded by Peter Yersley familiar letters on chemistry letter 16 my dear sir my recent research is into the constituent ingredients of our cultivated fields have led me to the conclusion that of all the elements furnished to plants by the soil and ministering to their nourishment the phosphate of lime or rather the phosphates generally must be regarded as the most important in order to furnish you with a clear idea of the importance of the phosphates it may be sufficient to remind you of the fact that the blood of man and animals besides common salt always contains alkaline and earthy phosphates if we burn blood and examine the ashes which remain we find certain parts of them soluble in water and others insoluble the soluble parts are common salt and alkaline phosphates the insoluble consists of phosphate of lime phosphate of magnesium and oxide of iron these mineral ingredients of the blood without the presence of which in the food the formation of blood is impossible both man and animals derive either immediately or immediately through other animals from vegetable substances used as food they had been constituents of vegetables they had been parts of the soil upon which the vegetable substances were developed if we compare the amount of the phosphates in different vegetable substances with each other we discover a great variety whilst there is scarcely any ashes of plants altogether devoid of them and those parts of plants which experience is taught as are the most nutritious contain the largest proportion to these belong all seeds and grain especially the varieties of bread corn peas beans and lentils it is a most curious fact that if we incinerate grain or its flower peas beans and lentils we obtain ashes which are distinguished from the ashes of all other parts of vegetables by the absence of alkaline carbonates the ashes of these seeds when recently prepared do not f of s with acids their soluble ingredients consist solely of alkaline phosphates the insoluble parts of phosphate of lime phosphate of magnesium and oxide of iron consequently of the very same salts which are contained in blood and which are absolutely indispensable to its formation we are thus brought to the further indisputable conclusion that no seed suitable to become food for man and animals can be formed in any plant without the presence and cooperation of the phosphates a field in which phosphate of lime or the alkaline phosphates form no part of the soil is totally incapable of producing grain peas or beans an enormous quantity of these substances indispensable to the nourishment of plants is annually withdrawn from the soil and carried into great towns in the shape of flower cattle etc it is certain that this incessant removal of the phosphates must tend to exhaust the land and diminish its capability of producing grain the fields of great britain are in a state of progressive exhaustion from this cause as is proved by the rapid extension of the cultivation of turnips and manglewuesle plants which contain the least amount of the phosphates and therefore require the smallest quantity for their development these roots contain 80 to 92 percent of water their great bulk makes the amount of produce fallacious as respects their adaptation to the food of animals in as much as their contents of the ingredients of the blood i.e. of substances which can be transformed into flesh stands in a direct ratio to their amount of phosphates without which neither blood nor flesh can be formed our fields will become more and more deficient in these essential ingredients of food in all localities where custom and habits do not admit the collection of the fluid and solid excrement of man and their application to the purposes of agriculture in a former letter i showed you how great a waste of phosphates is unavoidable in england and referred to the well-known fact that's the importation of bones restored in a most admirable manner the fertility of the fields exhausted from this cause in the year 1827 the importation of bones for manure amounted to 40 000 tons and huskieson estimated their value to be from 100 000 pounds to 200 000 pounds sterling the importation is still greater at present but it is far from being sufficient to supply the waste another proof of the efficacy of the phosphates in restoring fertility to exhausted land is afforded by the use of the guano a manure which although of recent introduction into england has found such general and extensive application we believe that the importation of 100 weight of guano is equivalent to the importation of 800 weight of wheat the hundred weight of guano assumes in a time which can be accurately estimated the form of a quantity of food corresponding to 800 weight of wheat the same estimate is applicable in the valuation of bones if it were possible to restore to the soil of england and scotland the phosphates which during the last 50 years have been carried to the sea by the Thames and the Clyde it would be equivalent to manuring with millions of hundred weights of bones and the produce of the land would increase one third or perhaps double itself in five to ten years we cannot doubt that the same result would follow if the price of the guano admitted the application of a quantity to the surface of the fields containing as much of the phosphates as have been withdrawn from them in the same period if a rich and cheap source of phosphate of lime and the alkaline phosphates were open to england there can be no question that the importation of foreign corn might be altogether dispensed with after a short time for these materials england is at present dependent upon foreign countries and the high price of guano and of bones prevents their general application and insufficient quantity every year the trade in these substances must decrease or their price will rise as the demand for them increases according to these premises it cannot be disputed that the annual expense of Great Britain for the importation of bones and guano is equivalent to a duty on corn with this difference only that the amount is paid to foreigners in money to restore the disturbed equilibrium of constitution of the soil to fertilize her fields england requires an enormous supply of animal excrement and it must therefore excite considerable interest to learn that she possesses beneath her soil beds of fossil guano strata of animal excrement in a state which will probably allow their being employed as a manure at a very small expense the copperliths discovered by dr. buckland a discovery of the highest interest to geology are these excrements and it seems extremely probable that in these strata england possesses the means of supplying the place of recent bones and therefore the principal conditions of improving agriculture of restoring and exalting the fertility of her fields in the autumn of 1842 dr. buckland pointed out to me a bed of copperliths in the neighborhood of clifton from half to one foot thick enclosed in a limestone formation extending as a brown stripe in the rocks for miles along the banks of the seven the limestone mile of limereges consists for the most part of one fourth part of fossil excrements and bones the same are abundant in the liass of bath eastern and broadway hill near evesham dr. buckland mentions beds several miles in extent the substance of which consists in many places of a fourth part of copperliths pieces of the limestone rock in clifton near bristol which is rich in copperliths and organic remains fragments of bones teeth etc were subjected to analysis and were found to contain above 18 percent of phosphate of lime if this limestone is burned and brought in that state to the fields it must be a perfect substitute for bones the efficacy of which is a manure does not depend as has been generally but erroneously supposed upon the nitrogenized matter which they contain but on their phosphate of lime the osseous breccia found in many parts of england deserves a special attention as it is highly probable that in a short time it will become an important article of commerce what a curious and interesting subject for contemplation in the remains of an extinct animal world england is to find the means of increasing her wealth in agricultural produce as she has already found the great support of her manufacturing industry in fossil fuel the preserved matter of primeval forests the remains of a vegetable world may this expectation be realized and may her excellent population be thus redeemed from poverty and misery the end of section 16 and the end of familiar letters on chemistry by justus libig