408 M. Becquerel on the Electricity of Flames. 



that it sometimes happens that a temperature is communicated 

 to the metal which does not give it any electricity. 



When the electricity acquired by the flame is received on 

 one of the plates of the condenser, we can, if we choose, put 

 this in communication with the ground by touching it with a 

 bit of moistened wood. Although the flame, whilst it is con- 

 tinually renewed, carries away with it the electricity that it 

 has acquired in .its contact with the metal, the experiment 

 proves that the discharge takes place still more rapidly in 

 operating as we have just indicated. But if, in place of 

 touching the flame with a bit of moistened wood, a plate of the 

 same metal is used as that which is placed on the capsule, it 

 is found that both become established in two different electric 

 states ; the plate which is red-hot takes the negative electri- 

 city, and that which is less heated, the positive electricity. 



Entirely similar effects are obtained when these two plates are 

 made of different metals : we believe, nevertheless, that their 

 intensity is more marked in certain circumstances. 



When the jet produced in the flame of a wax-candle by the 

 blow-pipe is used, the same effects are still found. 



Do these phaenomena result from a friction of the flame on 

 the metals ; or are they owing to an electro-motive action ? 

 We incline to the latter opinion. It is conceivable that there 

 might be a friction when a metal wire is plunged in the jet of 

 the blow-pipe ; but in a tranquil flame, such as that produced 

 by the combustion of alcohol, how could it take place ? Be- 

 sides, how could two plates of the same metal and of unequal, 

 thickness, plunged at the same time in a flame, each of them take 

 a different electricity from this cause, only that one has a tem- 

 perature more elevated than the other ; if an electro-motive 

 action be not admitted ? It is also very certain that these 

 phaenomena do not proceed solely from a difference of tempe- 

 rature in several parts of the same metal, for the extremity of 

 a plate of platinum has been reddened by Mr. Fresnel's pow- 

 erful lens without any development of electricity resulting 

 from it. 



These experiments have not any relation with those of 

 M. Ermann on the conducting properties of the flame of al- 

 cohol ; they might perhaps have more with the researches of 

 Volta on the combustion of a bit of amadou fixed to the extre- 

 mity of a stem communicating with one of the plates of the con- 

 denser. This illustrious natural philosopher found that when 

 the apparatus was in the open air unvitiated by proximity to in- 

 habited places, the amadou acquired an excess of positive elec- 

 tricity; which, according to him, proceeded from the ambient 



