PREFACE. XXXV 



were, mixed up together. It contains a col- 

 lection of problems, such as chemistry at pres- 

 ent requires to be resolved ; and a number of 

 conclusions, drawn according to the rules of 

 that science, from such observations as have 

 been made. 



These questions and problems will be re- 

 solved : and we cannot doubt, that we shall 

 have in that case a new physiology and a ra- 

 tional pathology. Our sounding line, indeed, 

 is not long enough to measure the depths of 

 the sea, but is not on that account less valuable 

 to us. If it assist us, in the mean time, to 

 avoid rocks and shoals, its use is sufficiently 

 obvious. In the hands of the physiologist, or- 

 ganic chemistry must become an intellectual 

 instrument, by means of which he will be en- 

 abled to trace the causes of phenomena invisi- 

 ble to the bodily sight ; and if among the re- 

 sults which I have developed or indicated in 

 this work, one alone shall admit of a use- 

 ful application, I shall consider the object for 

 which it was written as fully attained. The 

 path which has led to it will open up other 

 paths ; and this I consider as the most impor- 

 tant object to be gained. 



JUSTUS LIEBIG. 



GIESSEN, April, 1842. 



