76 Scientijic Notices — Miscellaneous. [Jan. 



As plants during vegetation exert a chemical action on the 

 atmosphere, sometimes converting- its oxygen into carbonic acid, 

 and at others decomposing the carbonic acid already existing in 

 it, the idea suggested itseU^ that if electricity were developed in 

 these processes of vegetation, their very extensive operation 

 would warrant one in attributing to them a considerable portion 

 of the electricity of the atmosphere. 



To investigate this subject, M. Pouillet examined the vegeta- 

 tion of seeds in an insulated situation, having a condenser con- 

 nected with the soil. Till the germs appeared at the surface, no 

 signs of electricity could be detected, but as vegetation advanced 

 it became very evident. For the success of this experiment it 

 is necessary that the air should be in a state of considerable 

 dryness. When this does not happen to be the case, the apart- 

 ment must be artificially dried by quicklime, or some other 

 absorbent. It is obvious that the soil could not acquire one 

 electric state without the opposite state in a corresponding 

 degree being communicated to the atmosphere. 



If then a languid vegetation on a surface of five or six square 

 feet be capable of producing very decided eflTects, may we not 

 reasonably conclude, that the influence of the same cause 

 operating over a large portion of the surface of the earth is fully- 

 adequate to the pioduction of* many of the phaenomena which 

 we observe ? 



A second memoir, by the same author, carries the subject still 

 further, and exhibits other causes, besides the process of vege- 

 tation, which contribute to supply the atmosphere with electri- 

 city. In the first memoir, he had shown that when two bodies 

 combine, electricity is developed ; in the second, he proves that 

 similar phsenomena attend the separation of bodies which were 

 previously combined, and he applies this fact to the numerous 

 instances of decomposition which nature is spontaneously pro- 

 ducing on the surface of our terraqueous globe. 



M. Pouillet, in his experiments connected with this inquiry, 

 employed two processes. The first resembles that adopted by 

 Saussure, in his experiments on evaporation, and consists in con- 

 uecting one of the disks of the condenser with the heated vessel 

 in which the subject of the experiment is to be placed. By the 

 other process, the heated vessel is dispensed with, and he makes 

 use of one of Fresnel's large lenses to heat the body whilst it 

 rests on a plate of platina. It should be remarked, that when 

 vessels of copper or iron, or of other materials on which the 

 substances under examination can act chemically are employed, 

 the result will be a complication of effect by which the phseno- 

 mena will sometimes be heightened, and at others neutralized. 



The results of his experiments are, first, that by mere evapora- 

 tion, as before stated, whether it be rapid or slow, no signs of 

 electricity are produced; secondly, that .evaporation from an 



