THE FARMER'S MONTHLY VISITOR. 



87 



ture and constitiitioii of plants, aud the natural 

 agents, wliicli contiibute to tlieir nutiinieiit and 

 growth. These are all extensive and coiii|)licated 

 brancliesof knowledge, and to coin|)relien(l them 

 thoroughly, the results of scientific observation 

 and of practiiMl experience are both cssi'iitial. 

 Science is, indeed, notliinj,' more than an orderly 

 and systematic arntngenient of the tiicts, which 

 observalion has disi-overed, aud of the couscriuun- 

 ces, which aj-c dcdiiccd lixMU tlieni. 



The last thirty years have witnessed tlie |inhli- 

 catiou of three scientilic works of the highest or- 

 der ou the application of chemistry to airricidture. 

 The first of these was Sir Humphrey Davy's Ele- 

 ments of Agricultural Chemistry, first published 

 in I8l:{, in the form of a coiu'se of Icctuies betiire 

 the Board of Agricnltiue iji London, in this 

 treatise the general poweiaof njaiier, which in- 

 fluence vegetation, the organization of plants, the 

 composition of soils, the constitution of the at- 

 mosphere, the nature and uses of manures, veg- 

 etable, animal and juineral, and a variety of sub- 

 jects both of scientific aud practical agriculture, 

 were treated with tin' clr;uiioss and ('iii;in:dity. 

 which distinguished tiiatcminem |i!]ili..-„,|il„r and 

 chemist. Aboul ti-n ye us aUcrwiuds appealed 

 Cliaptal's "ChemistryApplied to ALMicullin-c," a 

 second and enlarged edition of which w;is |)uli- 

 lished in 1H29. The same general subjects are 

 common to both these works; but the latter is 

 more particidarly a[)|-lical)le than the former to 

 practical husbandry, and especially that of Trance. 

 Most of the matter, however, is .applicable to the 

 agriculture of all countries ; and it is of the great- 

 er value as it treats of a variety of subjects" con- 

 nected with the economy of domestic jilc-. 



The work, which we have inenlioiied at the 

 Iiead ofthis article, is mainly devoted, as its title 

 imports, to the scientific relations of ihemistry to 

 agricultine, though running necessarily into prac- 

 tical views of both. It was presented "to the Brit- 

 ish Association tor the Advancement of Science 

 nt their animal meeting in 1840, in the form of a 

 report (;n the state of organic chennstry, and was 

 prepared at their request by Dr. Liebig who is a 

 professor of chemistry in the University of Gies- 

 sen in Hesse Darmstadt. 



The work is divided into two general heads : 

 Jst, The chemical processes in the mitrition of 

 vegetables; and 2d, The chemical processes of 

 fermentation, decay and putrefaction. The first 

 part is devoted to an examination of the substan- 

 ces, which contribute to the nutriment of plants 

 and of the changes which these substances under- 

 go " in the living organism." The chemical com- 

 pounds which contribute to plants their principal 

 constituents, carbon and nitrogen, are considered 

 ntidor this head, .-uid " the relations in which the 

 vital functions of vegetables stand to the animal 

 econoiny and to other phenomena of nature." 

 The second part treats of the chemical processes, 

 through which the destruction of animals and 

 plants af>er death is effected, "the changes which 

 organic substances undergo in their conversion 

 into inorganic compounds," and the causes by 

 which these changes are determined. 



It is impossible for us with the space allotted to 

 the subject ol agricultme to give even an outline of 

 all the new views of Professor Liebig, or to make 

 such extracts from his work as to afford a just cou- 

 ceptionof its value. As a treatise on the application 

 of chemistry to agricultin-e,it will rank with Davy's 

 Elements of Agric\dtural Chemistry, and it has an 

 advantage over the latter in embracing the results 

 of thirty additional years of observation and ex- 

 periment, during which chemistry, as a science, 

 has been in rapid course of improvement. In the 

 progress of the science, the discovery of new tiu:ts 

 lias led to the correction of radical errois in veg- 

 etable physiology, sijme of which Dr. Liebig has 

 for the first time [loiuted out to the public. Among 

 these there is none of greater importunce than the 

 opinion heretofore received among physiologists 

 that the fertility of the soil depends on the pres- 

 ence of a substance, wliicli they have deuomialed 

 humus. It has been considered as constituting 

 the principal nutriment of plants, itself the pro- 

 duct of the decay of other jilants. This sid>stance 

 exists under various modifications, and has re- 

 ceived a variety of names accoiding to the differ- 

 ent e.xternal ))roperties and cheiuical characteris- 

 tics, which it exiiibits. "Thus ulmin, humic acid, 

 coal of hiwius and humiii are names applied to 

 modifications of litmus," and they are obtained 

 by a v«riety of artificial processes. Dr. Liebig 



takes the position that " not the slightest ground 

 e.vists for the beliel'that one or the other of these 

 artificial products of decomposition of vegetable 

 matter exists in nature in the form and endowed 

 with the properties of the vegetable consituents 

 ofmoidd," and that "there is not a shadow of 

 proofth.it any one of them exerts any influence on 

 the gi'owth of plants either in the way of nourish- 



Vege 

 mus nil: 



iy>i.)Iogists have considered hu- 

 iri Ills possessing the properties of 

 vegetalile miiidd bearing the .same name, and this 

 opiinou has bv.cn the foundation of their theories 

 with regard to the agency of tiie latter in the mi- 

 trition of plants. 'I'iiey have also belit ved that 

 the substance, called humus, is extracted lioni the 

 soil by the roots of plants, and that the carbon it 

 contains contributes to tlieir nourishment. Dr. 

 Liebig combats these positions, and furnishes un- 

 answerable proof that "numus, in the form in 

 which it exists in the soil, does not yield the smal- 

 lest nourishment to plants." And he add.s, that 

 these incorrect opinions have rendered it impos- 

 sible U< iiiid-rstand "the true theory of the nutri- 

 li\cpiiM-ess in vegetation," "and deprived us of 

 cmr lie>i ;.niile to a rational practice in agricul- 

 ture.'' Without an accurate knowledge of the 

 substaucivs. which contribute to the nomishment 

 of plants and the sources from which these sub- 

 stances are derived, any great improvement, as 

 he justly observes, in practical agriculture, is 

 hopeless. 



We have not space to present the train of ob- 

 servations, which he advances in opposition to 

 the generally received opinions referred to and 

 ill support of his own conclusions. Having 

 shown that the carbon of plants is not derived 

 from humus, he proceeds to prove that it must be 

 extracted from the atmosphere, in which it exists 

 in the tiirm of carbonic acid and in combination 

 with oxygen — aud it involves, to use the language 

 of Dr. Liebig, " the consideration of the two most 

 reniarkalile phenomena, w liich, by tlieir recipro- 

 cal infiueuce, niaintuiu the life of the individual 

 animals aud vegetables, and the continued exis- 

 tence of both kingdoms of organic nature." Let 

 us state briefly a lew of his positions. 



//iimijs is woody fibre in a state of decay: it 

 possesses the property of converting oxygen gas 

 into carbonic acid ; and there is this difference 

 between Aumits and inauld, that the latter is the 

 product of the complete decay of woody fibre. 

 Humus, by converting oxygen into carbonic acid, 

 is constantly supplying plants with their most im- 

 portant food, and thus^ although not itself absorb- 

 ed and assimilated, performs an important func- 

 tion in vegetation. Ploughing, by loosening the 

 soil, gives free access to the air, which being 

 brought into contact w'nhhumus produces carlslti- 

 ic acid. During the growth of plants they pos- 

 sess the jiower of absorbing moisture by tlieir 

 roots and with it air and carbonic acid. But 

 when a plant is mature and its leaves, the organs 

 by which it derives nutriment from the atmos- 

 phere, are perfect, it uo longer needs the carbon- 

 ic acid contained in the soil. 



The nitrogen, which enters into the composi- 

 tion of plants, is derived fi'om ammonia, the sim- 

 plest of all the compounds of nitrogen. This fact 

 Dr. Liebig establishes by indisputable evidence, 

 and he shows by experimeuts that it is coutainetl 

 in the atmosphere. Ammonia being extremely 

 soluble ill water, it cannot remain long in the at- 

 mosphere, but becomes condensed with every 

 shower of rain and descends with it to the earth. 

 He concludes, therefore, that rain-water must al- 

 wavs contain ammonia. This is a new discovery : 

 no "previous analysis of rain-water had sliowii its 

 presence. He contends that it must alw.ays be 

 present; and repeated experiments made by him 

 at Giessen go tin- to establish his position. These 

 experiments were made with the greatest care 

 and under circumstances in the highest degree 

 favorable to their exactness. Animal manure acts 

 only by the formation of ammonia. Decayed 

 wood absorbs amnioniacal gas, which is separated 

 from it again when moistened with water. Thus 

 humus is not oul}', as has been seen, a constant 

 source of carbonic acid, but is the instrument al- 

 so of conveying nitrogen to plants. 



"Carbonic acid, water and ammonia, (to use the 

 language of Dr. Liebig) contain the elements nec- 

 essary for the support of animals and vegetables. 

 The same substances are the ultimate products 

 of the cheiniciil processes of decay and putrefiic- 



tion. All the innutnerable products of vitality re- 

 sume, after death, the original forin from which 

 they sprung, and thus death— the comjilete disso- 

 lution of an existing generation — becomes the 

 source of life for a new one." 



The opinion that the atmosphere contains the 

 principal food of plants in the form of carbonic 

 acid (in the state of an oride) is not new. It has 

 been advanced and delended by Priestley and oth- 

 ers, though not generally adopted. One of the 

 reasons why this great principle in the vegetable 

 economy has not been universally admitted is 

 thus assigned by Dr. Liebig : 



" There scarcely exists a theory in natural Bci- 

 ence, in favor of which there are more clear and 

 decisive arguments. How, then, are we to ac- 

 count for its not being received in its full extent 

 by most physiologists, for its being even disputed 

 by many, and considered by a f«;w as quite re- 

 futed ? 



"All this is due to two causes, which we shall 

 now consider : 



"One is that in botany the talent and labor of 

 inquirers have been wholly spent in the exami- 

 nation of form and structure ; chemistry and 

 physics have not been allowed to sit in council 

 upon the explanation of the most simple process- 

 es ; then- experience and their laws liave not been 

 employed, though the most powerful means 

 of help in the acquirement of true knowledge. 

 They have not been used because their study has 

 been neglected. 



"All discoveries in physics and in chemistry, 

 all explanations of chemists, must remain without 

 fruit and useless, because even to the great lead- 

 ers in physiology, carbonic acid, ammonia, acid 

 aud bases, are sounds without meaning, words 

 without sense, terms of an unknown language, 

 which awaken no thoughts and no associations. 

 They treat these sciences like the vulgar, who 

 despise a foreign literature in exact proportion to 

 their ignorance of it; since even when tlioy have 

 had some acquaintance with them, they have not 

 understood their .spirit and application. 



" Physiologists reject the aid of chemistry in 

 their inquiry into the secrets of vitality, although 

 it alone could guide them in the true path ; they 

 reject chemistry, because in its pursuit of knowl- 

 edge it destroys the subjects of its investigations; 

 but they forget that the knife of the anatomist 

 must destroy its organs, if an account is to be giv- 

 en of their form, structure and functions." 



On the assimilation of hydrogen, as well as on 

 the origin^and assimilation of nitrogen, and also 

 on the inorganic constituents of plants, Dr. Liebig 

 presents a variety of interesting facts and deduc- 

 es from them the most important conclusions. 

 On the art of culture, interchange of crops, ma- 

 nures, &c. his work abounds in valuable infonna- 

 tion of a scientific as well as a practical nature. 

 It should be in the hands of every scientific agri- 

 culturist. We have seen only one copy of a Lon- 

 don edition ; but we are glad to perceive that it 

 is to be reprinted in Boston, and that it will be 

 shortly tbmid in the bookstores. 



We shall be much mistaken if this publication 

 is not regarded as constituting a new era in agri- 

 cultural science. It is the first attempt to make a 

 practical application of organic chemistry to agri- 

 culture. Organic chemistry is itself a new sci- 

 ence; though it has been pursued with a diligence, 

 which has shed much light upon the atomic con- 

 stitution and ultimate principles of vegetable sub- 

 stances. Dr. Liebig has struck out a new path 

 in pointing out its connection with scientific and 

 practical agriculture, and the manner in which 

 his task has been performed, is in the highest de- 

 gree creditable to himself, his country and the 



A Lesson for Usefulness. 



Extravagance aud recklessness as to waste are 

 among the besetting sins of the age. It is but loo 

 common for many of the thoughtless and improv- 

 ident to see property wasted and thrown away; 

 and there are a few who are careful and provi- 

 dent of their own who will not turn their hands 

 to i>revent the destruction of what belongs to 

 other.s. The wastage of the ordinary food daily 

 prepared is an item of no inconsiderable amount: 

 in some families, whose heads and managers nev- 

 er could submit to the drudgery of studying econ- 

 omy, this waste is a husiuessof every day : adults 

 waste the food that is set before them, and chil- 

 dren follow the example. This wastage, w« do 



