ELECTRICAL CONDUCTIVITY OE AIR AND SALT VAPOURS. 
411 ) 
spray settled in tlie bulb and first half of the U-tube, and was returned to li through 
a tube, DD, up which the Ikpiid was forced by air introduced by the tube K. 
Fig. 1.—TT Platinum tube. EE Electrode. S Sjjrayer. R Reservoir of salt solution. M Air manometer. 
Water bath. Pt, Rh Thermo-couple wires. H Galvanometer. B Battery. Ci C 2 C 3 
Commutators. 
The supply of compressed air used was obtained by means of two water injector 
pumps similar to the one used in the previous work on the conductivity of flames. 
Some of the air was allowed to escape by bubbling through mercury which served to 
keep its pressure nearly constant, and the rest was passed through a large carboy 
to smooth out small oscillations in the pressure. The air pressure at the sprayer 
was measured by means of the water manometer, M, and was kept constant at 
50 centims. This arrangement gave enough air to work the sprayer and also the 
furnace except at temperatures above about 1100° G., when the air supply to the 
furnace was supplemented by oxygen from a cylinder by means of which a tempera¬ 
ture of 1400° C. could be obtained. 
The temperature of the tube was measured by means of a platinum platinum- 
rhodium thermo-couple, which was simply connected directly to an Ayrton-Mather 
dead-beat galvanometer of about 500 ohms resistance. The platinum wire served to 
support the tube, and the Pt/Rh wire was fused on to the tube at a point on its 
upper surface, so that the tube itself formed one of the elements of the couple. The 
3 H 2 
