Biographical Memoir of Mark Augustus Pictet. 3 



worn out with labour, and threatened with a serious indispo- 

 sition, resigned his chair in favour of our author. This im- 

 portant situation he held during the whole of his life ; and 

 from the elegance of his personal appearance, the agreeable- 

 ness of his elocution, and his talent, for perspicuous and ex- 

 perimental illustration, he discharged its duties with the greatest 

 success. 



This was the period of the renovation of Chemistry, when a 

 few superior spirits, throwingoffthetrammels of ancient systems, 

 gave a new impulse to physical inquiry. The gaseous sub- 

 stances were discovered ; water and air were decomposed ; 

 minerals were reduced to their elements, and new fields of re- 

 search were laid open to the ambition of the philosophic in- 

 quirer. M. Pictet participated in the general ardour, and he 

 published in 1791, his Essai sur le Feu, a work which added 

 greatly to his reputation, and became the ground-work of many 

 celebrated inquiries. Here he demonstrated the reflection of 

 radiant heat, and the apparent reflection of cold. He discovered 

 many new facts respecting the passage of heat through 

 bodies; and he determined the distribution of heat in the 

 lower strata of the atmosphere, and at different times of 

 the day and the night. The lastof these experiments have led to 

 the explanation of the phenomenaof Dew ; while theformer con- 

 ducted M. Prevost to his beautiful theory of the moveable 

 equilibrium of heat, which, though assailed in this country * 

 by shallow reasoning and vulgar abuse, is now adopted by 

 every philosopher in Europe. 



When M. Pictet had thus laid the foundation of new and 

 extensive researches, his career was interrupted by the poli- 

 tical pestilence which had sprung up in Europe. The hor- 

 rors of the French revolution were soon felt at Geneva, and 

 this peaceful city was involved in all the calamities of faction 

 and anarchy. The position which M. Pictet took amid these 

 disasters, was that of a patriot and a Christian. He strove 

 to reconcile the contending parties. He exposed his own 

 life in order to protect the magistracy from the fury of a 

 blinded populace; and he took up arms in defence of the 



* Supplement Encylopadia Britunniat. Article Dew. 



