THWARTED PLANS. 235 



The lectures l delivered by Humboldt were on the nature of 

 nitrous gas and the possibility of a more exact analysis of the 

 atmosphere : they were works founded upon the observations 

 he had made at Salzburg, and they were subsequently adduced 

 to disprove the statements of Lavoisier concerning the satu- 

 ration of nitrous gas with oxygen statements which at that 

 time were everywhere received with confidence. It was these 

 lectures also which afterwards gave occasion to some severe 

 criticism on the part of Gray-Lussac, then just entering on his 

 career. Ehrenberg is in error 2 when he asserts that it was in 

 these labours that Humboldt was assisted by 'his intimate 

 friend Gay-Lussac.' It was only upon his return from America 

 that Humboldt made acquaintance with the young chemist, 

 and from that time first dated their joint labours. 3 These 

 treatises, with sundry others on kindred subjects, were published 

 in a separate volume in 1799. 4 



In one of his latest letters to Willdenow, Humboldt thus 

 speaks of his reception at Paris and the alternate hopes and 

 disappointments to which he had been subject: 4 I was received 

 at Paris in a manner I could never have ventured to anticipate. 

 The venerable Bougainville was projecting another voyage 

 round the world, with the hope of reaching the South Pole. He 

 urged me to accompany him, and as I was just then occupied 

 with magnetic investigations, it occurred to me that an expe- 

 dition to the South Pole might prove more useful than a 

 journey to Egypt. I became absorbed in plans for this exten- 

 sive project, when all at once the Directory arrived at the heroic 



1 ' Allgemeine geographische Ephemeriden/ vol. ii. p. 176. 

 a * Gedachtnissrede auf Alexander von Humboldt,' p. 18. 



3 Arago's ( Sanimtliche Werke,' vol. iii. p. 16 $ ' Gedachtnissrede auf Gay- 

 Lussac.' 



4 'Versuche iiber die chemische Zerlegung des Luftkreises und liber 

 einige andere Gegenstande der Naturlehre.' Brunswick, 1799. The treatises 

 * On the Disengagement of Heat regarded as a Geognostic Phenomenon,' 

 and ' On the Influence of Chlorine and Oxygenated Muriatic Acid on the 

 Germination of Plants, together with a Description of the Phenomena/ 

 excited at that time considerable attention. During his absence from 

 Europe, a collection of his treatises, some purely scientific, some on prac- 

 tical mining, was published under the title, * Ueber die unterirdischen Gas- 

 arten und die Mittel ihren Nachtheil zu vermindern, &c.' (Brunswick, 1799), 

 to which a preface was affixed by William von Humboldt. 



