JUSTUS VON LIEBIG. 663 



qualitative analysis, and there is no other way of making one's 

 self acquainted with the various chemical properties of a body 

 than by first producing it out of the raw material, and then con- 

 verting it into its numerous compounds and so becoming ac- 

 quainted with them. 



By ordinary analysis one does not learn by experience what an 

 important means of separation crystallization is in skillful hands ; 

 and just as little the value of an acquaintance with the peculiari- 

 ties of different solvents. Consider only an extract of a plant or 

 of flesh which contains half a dozen crystalline bodies in very 

 small quantities imbedded in extraneous matter, which almost en- 

 tirely masks the properties of the others ; and yet, in this magma, 

 we can recognize by means of chemical reactions the peculiarities 

 of every single body in the mixed mass, and learn to distinguish 

 what is a product of decomposition and what is not, in order to 

 be able to separate them afterward by means which will exert no 

 decomposing influence. An example of the great difiiculty of find- 

 ing the right way in such researches is aft'orded by the analysis of 

 bile by Berzelius. Of all the numerous substances which he has 

 described as its constituents no one is, properly speaking, con- 

 tained in the natural bile. 



An extremely short time had been sufficient for the famous 

 pupils of the Swedish master to give a wonderful degree of per- 

 fection to mineral analysis, which depends on an accurate knowl- 

 edge of the properties of inorganic bodies ; their compounds and 

 their behavior to each other were studied in all directions by the 

 Swedish school with a keenness quite unusual previously and 

 even now unsurpassed. Physical chemistry, which investigates 

 the uniform relations between physical properties and chemical 

 composition, had already gained a firm foundation by the discov- 

 eries of Gay-Lussac and von Humboldt on the combining propor- 

 tions of bodies in the gaseous state, and those of Mitscherlich on 

 the relations between crystalline form and chemical composition; 

 and in chemical proportions the structure appeared to have re- 

 ceived its coping-stones and to stand forth completed. All that 

 foreign countries had acquired in by-gone times in the way of 

 discoveries now yielded rich fruit also in Germany. 



Organic chemistry — or what is now called organic chemistry 

 — had then no existence. It is true that Thenard and Gay-Lussac, 

 Berzelius, Prout, and Dobereiner, had already laid the foundations 

 of organic analysis, but even the great investigations of Chevreul 

 upon the fatty bodies excited but little attention for many years. 

 Inorganic chemistry demanded too much attention, and, in fact, 

 monopolized the best energies. 



The bent which I acquired in Paris was in a quite different 

 direction. Through the work which Gay-Lussac had done with 



