LIEBIO, JUSTUS, BARON VON. 



LIEBIG, JUSTUS, BARON VON. 



It WM translated into English from tha manuscript of the author by 

 Dr. Lyon Playfair, and dedicated to the British Anociatum for th 

 Advancement of Science. It is difficult to say how much of thi work 

 wm really original matter. The whole was however worked out with 

 the band of a master. His own original investigations on a great 

 variety of subjects, with those of Mulder on the nature and relations 

 of the nitrogenous products of plants, were arranged in the form of a 

 theory of vegetable life, which, however it might hare been appre- 

 hended by some in part*, now appeared for the first time as a consistent 

 whole. In his dedication the author lays that in this work he has 

 " endeavoured to develope in a manner correspondent to the present 

 state of science, the fundamental principles of chemistry in general, 

 and the laws of organic chapiistry in particular, in their application 

 to agriculture and physiology ; to the causes of fermentation, decay, 

 and pi' tit-faction ; to vinous and acetous fermentation, and to nitrifica- 

 tion. The conversion of woody fibre into wood and mineral coal, the 

 natute of poisons, contagions, and miaams, and the causes of their 

 action on the living organism, have been elucidated iu their chemical 

 relations." Perhaps one of the moat original portions of the book is 

 that devoted to the consideration of the action of poisons on the 

 system, in which he endeavours to show that poisons act injuriously 

 on the system, first, by 'causing definite chemical compounds with the 

 substances forming the flesh of the body poisoned, and thus rendering 

 life impossible, as in the case of arsenic and corrosive sublimate ; and 

 secondly, by inducing chemical changes by contact, as is seen in many 

 cases of inorganic bodies, in fermentation, putrefaction, and ereme- 

 causis or decay in organic bodies. In this way he explains the origin 

 of the various forms of contagious disease by the introduction into the 

 system of a substance capable of communicating to the solids and 

 fluids of the body the same state of change in which it is in itsc'lf. 

 This subject was brought by Dr. Lyon Playfair before the Glasgow 

 meeting of the British Association in 1840. 



It was not to ba expected that a work like this should at once be 

 adopted without opposition, or a thorough canvas of the conclusions 

 at which the author had arrived. From the very extent and nature 

 of the subject, the author was obliged to accept and adopt the con- 

 clusions of physiologists who bad not been so accurate iu their inves- 

 tigations as himself. In subsequent editions of this work he has 

 however availed himself of all the information brought to bear on his 

 subject by his critics, and has shown most conclusively that the only 

 prospect for the advancement of agriculture as an art is through a 

 thorough study of the physiology of plants. The effects of this work 

 soon became apparent, more especially in this country, in the regard that 

 was paid to chemical principles in the application of manures. That 

 many errors were committed, that Liebig himself turned out to be 

 wrong in some of his conclusions, was only what could be expected. 

 The application of chemistry to agriculture has however steadily 

 advanced, numerous treatises devoted to this subject have appeared, 

 and certain great advantages have been obtained. As an instance ol 

 the latter, the extensive application of phosphate of lime in the form 

 of bones, coprolites, and other compounds, when treated by sulphuric 

 acid, may be quoted 



One of the most recent of Liebig's contributions to agricultural 

 chemistry is his work entitled ' Principles of Agricultural Chemistry, 

 with Special References to the late Researches made in England.' 

 This work was translated by Professor Gregory of Edinburgh, anc 

 published in London in 1855. It was written in answer to the con 

 elusions arrived at from a long course of experiments by Mr. J. B 

 Lawes of Berkhampstead. These conclusions were in direct contra 

 diction to the principles previously laid down by the author, and he 

 states, " In fact all the experiments of Mr. Lawes prove exactly the 

 reverse of that which, in his opinion, they ought to demonstrate.' 

 Of this work the translator says, " It is, so far as I can judge, by far 

 the best of the author's writings on the important subject to which i 

 refers." This work contains, in the shape of fifty propositions, a 

 summary of the true relation between chemistry and agriculture, anc 

 may be regarded as the most matured of the author's works on this 

 important department of chemical inquiry. This controversy appears 

 to have be^n conducted on both sides with the most perfect tempei 

 and good feeling. 



Such works alone as the above might well have made a lasting anc. 

 enviable reputation; but from 1840 to 1855 Liebig was engaged 

 in the production of many other works. Iu 1837 ho commenced wit] 

 Wohler a Dictionary of Chemistry,' which was published in parts. 

 In 1839 Geiger's Handbook of Pharmaceutical Chemistry ' was pub- 

 lished, in which the part devoted to Organic Chemistry was written 

 by Liebig : this part afterwards appeared as a separate work. In 184 

 he edited the organic part of the late Dr. Turner's ' Elements o 

 Chemistry.' 



The volume on Agricultural Chemistry was regarded by th 

 author as only an instalment of what he owed the British Associatioi 

 in answer to their request for a report on the progress of Organ! 

 Chemistry. At the meeting held at Manchester in June 1842, Dr. Lyoi 

 Playfair read an abstract of Professor Liebig's report on Organi 

 Chemistry applied to Physiology and Pathology.' This able productio 

 wa published in the ' Transactions ' of the association. The entir 

 report appeared In 1842, under the title of 'Animal Chemistry, o 

 Chemistry in iU application to Physiology and Pathology,' 8vo 



/ondon. This work wa translated from the author's manuscript by 

 rofessor Gregory of Edinburgh ; a third and greatly improved edition 

 ras published in 1840. This work carried his chemical researches 

 roin the vegetable to the animal kingdom. What had been done for 

 he plant, vegetable physiology, and the agriculturist in the first work, 

 was now attempted to be done fur the animal, animal physiology, and 

 ho medical practitioner. In this work he pursued the sime plan as 

 n the Gint : he sot aside the hypothesis of a vital principle as a cause 

 n living phenomena, and examined them from a physical and chemical 

 mint of view. A strict comparison is instituted between that which 

 s taken into the body in the form of air and food with that which 

 'asB.-s out of the body, and all possible knowledge of the laws of 

 rganic chemistry is brought to bear upon the intermediate pheno- 

 mena of life. In this way he threw a flood of light on processes that 

 md hitherto been wrapped in obscurity. The phenomenon of animal 

 leat was seen to be more clearly the result of the oxidation of carbon. 

 Certain kin<is of food, as starch, sugar, and oil, were pointed out as 

 .he sources of the carbon, whilst Mulder's group of proteinaoeous 

 compounds were as clearly traced to their destiny in the production 

 of the living tissues. The source of fat iu the animal body, in spit 

 of the opposition of the French school, was traced to the oxidation of 

 ;ho hydrogen in the starch and sugar of the food. The nature of tho 

 excretions, especially of the urine, bile, and fseces, were carefully 

 examined, and manifold new analyses and results were given. The 

 impression this work has made on the science of physiology and tho 

 practice of medicine is not less than that of the last on botany and 

 agriculture. It at once called into activity an amount of chemical 

 investigation that has already led to the most important results, and 

 ;iven a new aspect to all physiological inquiry in the animal kingdom. 

 Whilst the microscope on the one hand has gone on developing new 

 structures, the chemist has demonstrated that these structures exhibit 

 life but in obedience to chemical laws. Numerous treatises have been 

 written on the chemistry of animal life, and all bear more or less tho 

 impress of the genius of Liebig. 



If the first work excited controversy, it could hardly fail to be pro- 

 duced by the second. Mulder accused Liebig of appropriating his 

 discoveries without acknowledgment, especially his great discovery 

 of protein. To this question Liebig, who, in the meantime had some 

 doubts with regard to the real nature of this substance, replied " Will 

 Mulder say what is protein ? " Wlu-ther this substance exists or not, 

 the discovery is undoubtedly due to Mulder of the identity in animals 

 and plants of' the substances known as fi brine, albumen, and caseiue, and 

 that the animal is dependent on the vegetable kingdom for its supply 

 of them, in one form or the other. The importance of this discovery 

 can hardly be overrated, whether protein lies at the foundation of those 

 nitrogenous matters or not. Many of Liebig's physiological views 

 have met with very decided opposition, and many of his opinions have 

 been shown to be incorrect But his great glory will always be the 

 method he pursued. By this method he has put the physiologist in 

 the right direction to attain the great aim and ends of his science. 

 These views are of the highest interest for mankind, as they involve 

 no lets questions than the very existence of man, and the best possible 

 means of enjoying that existence. 



However complete the first outlines of his theories might appear to 

 be, Liebig never ceased working at correcting and perfecting them. 

 Between the period of the publication of the editions of his works on 

 Agricultural and Animal Chemistry, his * Annalen ' and the conti- 

 nental journals teem with his papers on various points which had been 

 canvassed in his books ; and in all directions, in his own laboratory 

 and in other places, we find men working under his advice and direc- 

 tion. It was thus that, from the time the subject of food occupied hU 

 attention at all, he prosecuted new researches on the nature of the 

 food, and of those changes in the animal body by which it becomes 

 the source of life, and ultimately the material rejected from the 

 system. In 1849 another work was prepared for the English press, 

 and translated by Dr. Gregory. This was entitled ' Researches on the 

 Chemistry of Food.' In this work he gave an account of his experi- 

 ments on the changes which the tissues of the body undergo, and 

 which result iu the conversion of fibrine and albumen into gelatine, 

 and eventually urea. In these experiments he operated on large 

 quantities of animal flesh, and succeeded in demonstrating the uni- 

 versal presence of kreatine, a compound first described by Chevreul, 

 also of kreatinine, lactic acid, phosphoric acid, and inosiuic acid, in 

 the flesh of animals. In this work he also drew attention to the exist- 

 ence of phosphate of soda in the blood, and its power of 'absorbing 

 carbonic acid, as having an interesting relation with the function of 

 respiration. He has also shown in this work that the proper cooking 

 of food can only be carried on upon fixed chemical laws, and that 

 much improvement in the economical and sanitary relations of this 

 art may be expected from a larger knowledge of the changes undergone 

 by food in its preparation. 



In all his labours Liebig has ever striven to avoid being one-sided. 

 No one seema to have felt from time to time more acutely than himself 

 the fact that, after all, the organic body is not an apparatus of glass 

 tubes and porcelain dishes. He ever tried to penetrate into the nature 

 of those properties and laws which, acting upon the textures of the 

 human body, seemed to interfere with an anticipated necessary 

 chemical result. It is in this spirit that we find him prosecuting 



