76 
PROF. H. A. WILSON ON THE ELECTRICAL CONDUCTIVITY AND 
It appears that the conductivity and luminosity due to the sodium carbonate are 
nearly proportional to the square root of the concentration as with sodium chloride. 
The following results were obtained :— 
Solutions sprayed 
(grammes per litre). 
Conductivities. 
Luminosities. 
Flame A. 
NaCl. 
Flame B. 
Na 2 C0 3 . 
A/B. 
A/B. 
200 
181-2 
1-00 
1-00 
20 
18-12 
1-00 
1-00 
2 
1-812 
1 -00 
1-00 
0-2 
0-1812 
1-00 
1-00 
It appears that the conductivities and luminosities of sodium chloride and sodium 
carbonate in any chemically equivalent quantities are equal. 
r fhe luminosity due to a sodium chloride solution containing 20 gr. per litre 
was found to be equal to that due to a solution containing 20 gr. of sodium chloride 
and 200 c.c. of strong hydrochloric acid per litre. Thus an excess of HC1 does 
not affect the luminosity due to NaCl. This agrees with the conclusion that the 
effect of CHClg on the luminosity due to NaCl is due to the change in the character 
of the flame and not to chemical action. 
It was found that the sodium light luminosity due to a solution containing 18'12 gr. 
Na 2 C0 3 per litre was equal to that due to a solution containing 18'12 gr. Na 2 C0 3 , 
and 23'6 gr. K 2 C0 3 per litre. The conductivity due to the solution containing 
K 2 C0 3 was about nine times that due to the one containing only Na 2 C0 3 . The 
negative ions from the K 2 C0 3 must have diminished the number of positive sodium 
ions nine times, so that this result agrees with the conclusion that sodium light is not 
due to positive ions. 
Part IY.—The Relation Between the Conductivity and the Concentration 
of Salt Vapours in Flames. 
The earlier experiments of Arrpxenius* and of Smititells, Dawson and the 
writer! showed that the current is nearly proportional to the square root of the 
concentration when the concentration is small, Smithells, Dawson and the writer 
found that with larger concentrations the current due to oxysalts increases much 
more rapidly than as the square root of the concentration. In all these earlier 
* ‘ Wied. Ann.,’ vol. xliii., p. 18, 1891. 
t ‘Phil. Trans.,’ A, vol. 193, p. 89, 1899. 
