"#80 M. Matteucci on the Electricity of Flame, 



was that in which the two wires are of a clear red, without having 

 been visibly reached by the flame. This is, as far as I remember, 

 the result obtained by M. E. Becquerel, and accords with what 

 .we know to be the case with all bodies excepting metals, that is, 

 that their conducting power increases by heat. Now is this an 

 eflfect similai- to that undergone by liquids, in which conductibility 

 and electrolygation go on together, or is it rather a discharge like 

 that of the voltaic arc, favoured chiefly by the high temperature 

 of the electrodes which are thus disposed to a disaggregation ? 

 I have often seen a great deflection of the needle persist for a 

 •certain time, when the wires heated to a white heat are moved 

 from the upper to the middle portion of the flame, but this is a 

 subject which can only be discussed by the help of other experi- 

 ments, which I hope that you, who have begun this subject so 

 successfully, will find time to undertake. 



When, instead of an alcohol flame, that of oil or stearic acid 

 is employed, we find at first that the passage of the current is 

 .yearly null ; but by taking means to prevent the formation of a 

 •fitratHm of black matter on the electrodes, we soon find that 

 the conducting power of these flames is greater than that of 

 alcohol. In order to efi'ect this, I heat the platinum wires in a 

 spirit-flame, which I replace rapidly by that of the substances just 

 named, and I then find that the conductibility of these flames is 

 much greater than that of alcohol. Proceeding in the same 

 manner, I ascertained that the conducting power of the flames of 

 camphor or of gutta percha was much less than that of alcohol. 



If between the eleotrodes a thin plate of platinum is inter- 

 posed, which may be said to cut the flame in half, the conducti- 

 bility remains unaltered ; and if this plate has been heated pre- 

 viously, we find, on the contrary, that the conducting power is 

 increased. By making use of salt of strontian, or boric acid, or 

 chloride of copper dissolved in small quantities in alcohol, I have 

 been enabled to work with flames which, as is known, present 

 different colours due to volatilized matter : the conductibility of 

 these flames is greatly diminished, and this is particularly the 

 case with the flame rendered green by chloride of popper. 



The conducting power is visibly increased by a jet of vapour 

 of iodine or of mercury sent into the midst of the flame, and the 

 power is lessened by a jet of steam from water, or by holding 

 burning sulphur in contact with the flame. It would be very 

 curious to study the conducting power of steam at diffierent 

 atmospheres and densities, and above all, to ascertain whether 

 this conductibility is accompanied by electro-chemical decom- 

 position. 



I now proceed to the development of electricity by flame. I 

 had no difficulty in verifying the results which you have obtained, 

 and which I will express as follows:— We find in the flame 



