10 GUSTAV MAGNUS. 



that he lived in an age when natural science passed 

 through a process of development, with a rapidity such 

 as never occurred before in the history of science. 

 But the men who belonged to such a time, and co- 

 operated in this development are apt to appear in 

 wrong perspective to their successors, since the best 

 part of their work seems to the latter self-evident, and 

 scarcely worthy of mention. 



It is difficult for us to realise the condition of natural 

 science as it existed in Germany, at least in the first 

 twenty years of this century. Magnus was born in 

 1802; I myself nineteen years later; but when I go 

 back to my earliest recollections, when I began to study 

 physics out of the school-books in my father's posses- 

 sion, who was himself taught in the Cauer Institute, I 

 still see before me the dark image of a series of 

 ideas which seems now like the alchemy of the middle 

 ages. Of Lavoisier's and of Humphry Davy's revo- 

 lutionising discoveries, not much had got into the 

 school-books. Although oxygen was already known, 

 yet phlogiston, the fire element, played also its part. 

 Chlorine was still oxygenated hydrochloric acid ; potash 

 and lime were still elements. Invertebrate animals 

 were divided into insects and reptiles ; and in botany 

 we still counted stamens. 



It is strange to see how late and with what hesita- 

 tion Germans applied themselves to the study of natural 



