﻿Electricity in Flames containing . Metallic Vapours. 877 



0*6 x 10~ 8 mg. Na. Our experiment was slightly modified 

 to allow the tests being carried out under the same conditions 

 as those o£ Aselman : on the assumption that each sodium 

 atom conveyed one elementary charge, our observations of 

 the current and time corresponding to the strip giving a just 

 perceptible colour for one second on subsequent testing, gave 

 1*0 x 10 -8 mg. Na as the amount, which is in moderate 

 agreement, 



considering the nature of the experiment. 



§ 8. Experiments on the Negative Carriers. 



Measurements of the current produced by the introduction 

 of a bead of salt into the flame for various positions of the 

 platinum strip were also made with the same arrangement 

 of apparatus, but with the insulated electrode charged 

 negatively. In this case, if the strip be horizontally level 

 with the bead, the introduction of the bead causes the current 

 to diminish. As the strip is raised, a point is reached where 

 the introduction of the bead causes no change in the current, 

 and after this the metal vapour produces the usual increase 

 of current found for the positive carriers. A typical curve 

 is shown in fig. 5. 



Current — * 



If the earthed electrode be further removed from the 

 flame, the deflexions all decrease in the same way as with 

 the positive carriers, but a path of 1 cm. extra in air decreases 

 the maximum deflexion for the negative carriers to A., while 



