Mr. C. Tomlinson on the Ignis Faiuus. 4:69 



laid the foundation of Pneumatic Chemistry. Among his 

 experiments are a considerable number on the inflammable 

 air produced during the decomposition of various kinds of 

 vegetable, and in vol. i., page 209, he says : — " The air from 

 marshes also, which, with Sig. Volta, I doubt not comes from 

 putrefying vegetable substances, I have also found to be 

 equally permanent ;" that is, not absorbed by water, as in 

 the case of fixed air. 



The name of Volta makes me pause for a moment to ex- 

 press my astonishment that Professor Kamtz, of the University 

 of Halle, in his celebrated Lehrbuch der Meteorologie, published 

 in 1832, in the section on Irrliclder oder Irrwische {Ignes 

 fatui, Ambulones, Feux fillets), expresses his opinion, and 

 notes it as a remarkable fact, that no physicist has specially 

 examined the nature of these lights (vol. ii. p. 490), and yet 

 he gives a multitude of authorities most of whose observations 

 are of very little value, except in the case of Volta, who, as 

 he says, supposed that marsh-gas or carburetted hydrogen is 

 the cause of these lights, and that the gas is kindled by means 

 of an electric spark *. 



Now it is surprising that Kamtz, with his extensive 

 knowledge of scientific literature, relating in any way to 

 Meteorology, should have ignored a work published in 1787, 

 on Meteors, by the Abbe Bertholon, Professor of Experimental 

 Physics at Languedoc, and member of various scientific 

 societies. Taking advantage apparently of Priestley's dis- 

 coveries, for, as he appropriately remarks, it was impossible 

 to explain the Ignis Fatuus before gases were discovered, he 

 describes a capital experiment which we must hear him relate 

 in his own language : — 



" II est bien prouve, par 1' experience et l'observation, 

 que, dans les marais et les terrains marecageux, il y a de l'air 

 inflammable ; il sufnt, pour en obtenir, de remuer avec une 

 canne la vase de ces endroits, aussitot on verra s'en echapper, 

 a travers de l'eau qui en couvre plus ou moins la surface, une 

 quantite assez considerable. Si dans cet instant on approche 

 la lumiere d'une bougie on verra aussitot l'air inflammable 

 s'allumer, et la flamme s'etendre au loin/'' f 



The gas thus formed has often been collected in bottles full 

 of water inverted over the spot ; it was found by Sir 

 Humphry Davy and others to contain carbonic acid and a 

 small quantity of nitrogen, the proportion of either or both of 

 which would of course influence the character of the flame. 



* His reference is to Volta, Opere iii. p. 46. 



t Tome Second, p. 10. _ > 



