NA TURE 



25 



THURSDAY, NOVEMBER 10, 1904. 



JUSTUS VON LIEBIG AND FRIEDRICH 

 MOHR. 



Monographieen aits der Geschichtc der Chemie. 

 Herausgegeben von Dr. Georg W. A. Kahlbaum. 

 viii. Heft. Justus von Liebig und Friedrich Mohr 

 in ihren Briefen von 1834-1S70. Pp. viii + 274. 

 (Leipzig : Johann Ambrosius Barth, 1904.) Price 

 8 marks. 



DR. KAHLBAUM continues to put tliose chemists 

 who are interested in the personal history of their 

 science under an obligation to him by reason of the 

 care and assiduity which he devotes to the editing of 

 the letters of the great leaders of chemical inquiry 

 such as Berzelius, Liebig, Wohler, and others, as these 

 from time to time come into his keeping. The volume 

 before us deals with the correspondence of Liebig and 

 Friedrich Mohr. 



Of Liebig it is unnecessary at this date to say any- 

 thing. His name and personal characteristics are 

 well known to all who are interested in science, and his 

 position in the history of science is assured for all 

 time. Whilst his correspondence with Mohr adds but 

 little to our knowledge of him as a man, it throws 

 many sidelights on incidents which occurred during 

 the most interesting and active periods of his 

 career. Thus, for example, we learn for the first time 

 of the relative share of Liebig and VVbhler in the work 

 which resulted in the classical memoir on bitter almond 

 oil. Most of the e.xperimental work was due to 

 Wohler; the interpretation of the facts and the com- 

 pilation of the memoir was made by Liebig. It would 

 appear, in fact, that Wohler never saw the memoir 

 until the proof of it was sent to him. 



Indeed, the chief interest of the correspondence, so 

 far as it relates to Liebig, is concerned with his work 

 as editor of the famous periodical — the Annalen der 

 Chemie und Pharmacie — which is now permanently 

 associated with his name. 



The name of Friedrich Mohr is much less familiar, 

 at all events to the chemists of this generation ; and 

 yet the author of the " Titrier-methode " — the practical 

 founder of the art of volumetric analysis — deserves to 

 be had in remembrance. He was a representative of 

 a type of man of which few examples, at least in this 

 country, are left to-day, viz. that of the scientific 

 apothecary. He was by instinct, training, and practice 

 a man of science, and he brought his knowledge, ex- 

 perience, and aptitudes as a man of science to the 

 exercise of his calling. In this respect he resembled 

 many of those who laid the foundations of modern 

 chemical science. In the early part of the last century 

 the occupation of the apothecary was practically the 

 only one open to the man who had his living to make, 

 and who at the same time wished to exercise his passion 

 for chemical inquiry. Teaching appointments were 

 few, and even where chemistry was taught the 

 opportunities for experimental work were very meagre. 

 Mohr was born in Coblenz at about the time that 

 Dalton gave the New Philosophy to the world. His 

 father, Karl Mohr, apothecary, town councillor and 

 NO. 1828, VOL. 71] 



member of the Rhenish Medical College, was a person 

 of some importance in the city, and it was probably 

 in his house that the authors of this correspondence 

 first made each other's acquaintance. 



Coblenz, from its proximity to the French frontier, 

 was the scene of many stirring episodes during the 

 early years of the nineteenth century, and Mohr him- 

 self lived through the time of, and was personally 

 witness to, the rise and collapse of French military 

 power during the interval between Moscow and Sedan, 

 .^s a little boy he might have seen the passage of 

 the Rhine by the French troops on the occasion of 

 Napoleon's invasion of Russia, and have spelled out 

 the magniloquent inscription on the fountain before 

 St. Castor which commemorates that event, as well as 

 the caustic words which St. Priest, the Russian com- 

 mander following on the heels of the retreating French, 

 caused to be added : — " Vu et approuve par nous. 

 Commandant Russe de la Ville de Coblence : Janvier 

 \er 1814." As an old man he saw, after the dehade 

 of Sedan, the spectacle of a ruined and discredited 

 War Minister skulking about in the twilight under the 

 shade of the chestnuts in the Poppelsdorfer .\l!ee in 

 Bonn in just fear of the taunts and insults of the un- 

 fortunate soldiery whom he had betrayed. 



In 1829 Mohr went to Heidelberg, where he came in 

 contact with Leopold Gmelin. He had already 

 acquired a considerable knowledge of operativ<» 

 chemistry and of pharmacology under his father's 

 tuition. In those far-off days the laboratory of an 

 apothecary was a reality, and those who practised the 

 calling were not merely chemists by prescription, but 

 were such in fact. They were for the most part well 

 skilled in chemical processes, and actually made the 

 greater number of the substances in which they dealt. 

 The influence of this early training is to be seen in 

 the character and scope of Mohr's subsequent work. 

 He was essentially a practical chemist, and his 

 services to the science consisted mainly in the improve- 

 ments he effected in operative chemistry. Many of 

 these humble but useful inventions were not calculated 

 to bring their author much fame, but if his connection 

 with them is well-nigh forgotten they at least secured 

 for him the gratitude of his contemporaries. How 

 many of the present generation of workers, it may be 

 asked, associate his name with that commonest of 

 laboratory appliances — the cork-borer? 



Mohr remained at Heidelberg two years, and then 

 repaired to Berlin to listen to Heinrich Rose's lectures. 

 In 1832 he returned to Heidelberg and took his degree 

 —summa cum laude. What a summa cum Jaude 

 meant in 1832, so far as regards chemistry, may be 

 inferred from the fact that the " hoch beriihmten 

 Fuhrer," Gmelin, recorded that "the Herr Kandidat 

 answered his questions on the chemical relations of 

 iodine, the preparation of potassium iodide, the dis- 

 covery of arsenic and on the preparation and com- 

 position of ether to his complete satisfaction." 

 Creuzer found that he displayed considerable know- 

 ledge of what the old Greeks and Romans knew of 

 botany and materia medica, and that he had a com- 

 petent acquaintance with their languages ; Muncke 

 was satisfied with his answers concerning the balance, 



C 



