X PREFACE TO THE 



the manner in which it has been edited in this coun- 

 try, have met with his entire approbation. To Dr. 

 Playfair the editor is also indebted for some valuable 

 suggestions which were followed in preparing the 

 second edition, and for which he would express his 

 thanks. 



A copious index, in which the original work is de- 

 ficient, has been added, and numerous errors of the 

 English press have been corrected. 



The estimation in which Professor Liebig's work 

 was viewed by the ^'British Association for the Ad- 

 vancement of Science," before whom it was brought 

 as a Report, has been expressed by Professor Gregory, 

 of King's College, in the remark, ^^ that the Association 

 had just reason to be proud of such a work, as origi- 

 nating in their recommendation." 



On the 30th of November, 1840, at the anniversary 

 meeting of the Royal Society, one of the Copley 

 medals was awarded to the author ; and on this occa- 

 sion, in his absence, the President, the Marquis of 

 Northampton, addressed his representative, Professor 

 Daniell, as follows. 



'^ Professor Daniell, I hold in my hand, and deliver 

 to you one of the Copley medals, which has been 

 awarded by us to Professor Liebig. My principal 

 difficulty, in the present exercise of this the most 

 agreeable part of my official duty, is to know wheth- 

 er to consider M. Liebig's inquiries as most important 

 in a chemical or in a physiological light. However 

 that may be, he has a double claim on the scientific 



