M. Pouillet on the Electricity of Elastic Fluich. 59 



charged with electricity. But it is evident, that during one 

 second the weight of oxygen, which combines or disengages 

 during a languid vegetation, which has only three or four 

 square feet long, is a weight so feeble, and a fraction of a mille- 

 gramme so imperceptible, that the electricity which it disenga- 

 ges is not sensible to the condenser. One is apt to fear after 

 this that the electricity has another source, and that it can only 

 be developed by some foreign cause ; but upon reflection we 

 see that the earth of the capsules is so dry that it becomes an 

 imperfect conductor ; that the electricity is retained ; and that 

 it is it which charges the condenser. To be certain of this, it 

 is sufficient to place successively in contact wuth the condenser 

 1, 2, 3, or a greater number of capsules, and we shall see the 

 charge increase in proportion as the number increases ; in 

 short, it is sufficient to place them in communication with the 

 ground for a long time, when they will no longer give a charge 

 to the condenser, and it will be many hours after that before 

 they communicate a sensible electricity. It is without doubt 

 this imperfect conductibility of the dried earth which has ren- 

 dered it impossible for me to observe until now any electrical 

 charges during the periods of day or night, although I took 

 every precaution to observe it, presuming, that, if the disen- 

 gagement of carbonic acid produce resinous electricity in the 

 ground, the disengagement of oxygen ought, on the contrary, 

 to produce vitreous electricity. 



It is perhaps the same cause which has given birth to ano- 

 ther phenomenon, which I have not yet studied sufficiently to 

 give an exact account of it. It happened twice that the electric 

 signs had ceased during two or three days, and that they were 

 then presented in opposite directions, — that is to say, the cap- 

 sules had exhibited vitreous electricity, and had continued to 

 exhibit it with a very weak intensity during the rest of the 

 vegetation. 



The following are the results of all these experiments : — 



1. That the gases disengage electricity when they combine 

 either with one another, or with solid or fluid bodies. 



That in these combinations the oxygen disengages always 

 positive electricity, and the combustible bodies negative elec- 

 tricity ; and that raciprocally, when a combination is dissolved, 

 each of the elements wanting the electricity which it had dis- 



