PKEFACE. 



i THE letters contained in this little Yolume embrace some of the most impor- 

 tant points of the science of Chemistry, in their application to Natural Phi- 

 losophy, Physiology, Agriculture and Commerce. Some of them treat of 

 subjects which have already been, or will hereafter be, more fully discussed in 

 my larger works. They were intended to be mere sketches, and were written 

 for the especial purpose of exciting the attention of governments, and an en- 

 lightened public, to the necessity of establishing Schools of chemistry, and 

 of promoting, by every means, the study of a science so intimately connected 

 with the arts, pursuits, and social well-being of modern civilized nations. 



For my own part I do not scruple to avow the conviction, that ere long, 

 a knowledge of the principal truth of Chemistry will be expected in every 

 educated man, and that it will be as necessary to the Statesman and Political 

 Economist, and the Practical Agriculturist, as it is already indispensable to 

 the Physician and the Manufacturer. 



In Germany, such of these Letters as have been already published, have 

 not failed to produce some of the results anticipated. New professorships 

 have been established in the Universities of Gottingen and Wurtzburg, for the 

 express purpose of facilitating the application of chemical truths to the prac- 

 tical arts of life, and of following up the new line of investigation and re- 

 search the bearing of Chemistry upon Physiology, Medicine, and Agricul- 

 ture, which may be said to be only just begun. 



My friend, Dr. Ernest Dieffenbach, one of my first pupils, who is well 

 acquainted with all the branches of Chemistry, Physics, Natural History, and 

 Medicine, suggested to me that a collection of these Letters would be accepta- 

 ble to the English public, which has so favorably received my former works. 



I readily acquiesced in the publication of an English edition, and undertook 

 to write a few additional Letters, which should embrace some conclusions I 

 have arrived at, in my recent investigations, in connexion with the application 

 of chemical science to the physiology of plants and agriculture. 



My esteemed friend, Dr. Gardner, has had the kindness to revise the manu- 

 script and the proof-sheets for publication, for which I cannot refrain expressing 

 my best thanks. 



It only remains for me to add a hope, that this little offering may serve to 

 make new friends to our beautiful and useful science, and be a remembrancer 

 to those old friends who have, for many years past, taken a lively interest in 

 all my labors. 



JUSTUS LIEBIG. 

 Giessen, August, 1852. 



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