88 
PROF. H. A. WILSON ON THE ELECTRICAL CONDUCTIVITY AND 
Part VI.—Summary of Results and Conclusion. 
The chief results obtained are as follows :— 
(l.) The luminous vapours of salts in a Bunsen flame are not deflected appreciably 
by an electric field. 
(2.) The positive ions present in the luminous vapour can be made to move out of 
it by an electric field. 
(3.) The positive ions are not luminous, but can form luminous vapour after 
recombination. 
(4.) The velocity of the positive salt ions in flames is about 1 cm. per second for 
1 volt per centimetre and is the same for all salts. 
(5.) The conductivity and luminosity of sodium chloride both vary nearly as the 
square root of the concentration of the salt vapour in the flame. 
(6.) The conductivities and luminosities of chemically equivalent amounts of sodium 
chloride and sodium carbonate are equal. 
(7.) A considerable excess of hydrochloric acid does not change the luminosity due 
to sodium chloride and slightly increases the conductivity of the flame. 
(8.) A large excess of hydrochloric acid obtained by the introduction of 
chloroform vapour diminishes the luminosity due to NaCl about 50 per cent., 
and diminishes the conductivity about six times. The percentage changes in 
the luminosity and conductivity are independent of the concentration of the NaCl 
vapour. 
(9.) The CHClg increases the current due to large potential differences, but diminishes 
the conductivity as measured by the ratio of the current to the uniform potential 
gradient in the flame. 
(10.) When the drop of potential at the negative electrode is got rid of by putting 
K 2 C0 3 on it, the CHC1 3 diminishes the current to about the same extent as the 
conductivity. 
(ll.) The presence of a large amount of K 2 C0 3 does not change the luminosity 
due to Na 2 C0 3 , although the K 2 C0 3 greatly increases the total conductivity. 
(12.) The variation of the conductivity (c) with the concentration (k) for alkali 
9 -I 
c — 1 
salts can be represented by the equation 10 4 £ = 
the constants a and b for each salt. 
(b + ac ), using proper values of 
(13.) The equation 10 4 & 
c 2 — 1 
(b + ac) can be deduced from the ionic theory and 
the fraction of the salt molecules which are ionised is equal to b/(b + ac). 
(14.) Alkaline chlorides and carbonates impart equal conductivities to the flame 
for chemically equivalent concentrations. 
