OF FLAMES CONTAINING SALT VAPOURS. 
501 
altering the water supply to the pump. A very considerable change in the water 
supply was necessary to appreciably alter the pressure indicated by the manometer, 
M. The air pressure used was 180 centims. of water, and it was very easily kept 
constant within 2 or 3 millims., only very occasional adjustments being required for 
this. 
The coal gas was passed through a regulator, R, consisting of a bell-jar suspended 
in water from one arm of a balance and arranged as shown in fig. 1, so that, when the 
gas in the jar attained the required pressure, the jar rose and cut off the gas supply. 
After passing through this regulator the gas supply was connected with a gasometer, 
H, which served to maintain the pressure steady. The weights on the gasometer 
were adjusted so as to produce a pressure equal to that at which the regulator partly 
cut off the gas. The gas was passed through a constriction, L, and then allowed to 
mix with the air and spray from the sprayer, S, in the globe, G, 
The pressure of the gas supply was measured on the water manometer, M', by 
means of a cathetometer reading easily to O’Ol centim. The gas pressure used was 
3'62 centims. of water, and it was easily kept constant within O’Ol centim. by 
occasionally altering the weights on the gasometer and in the j^an of the balance. 
The mixture of gas and air passed along the tube, E, into a globe, G', and from 
this into the flame tube, T. The tube, T, was supported by a wider brass tube, 
provided at its upper end with threg screws for centreing the flame tube, and fixed 
into an octagonal wooden block, D, 3’5 centims. thick and 20 centims. across (see 
fig. 2). A cylindrical glass shade, 15 centims. in diameter and 16 centims. high, 
rested in a circular groove in the block, D, and on this a flat tin plate was placed, 
having a circular hole at its centre, 3 centims. in diameter, for the escape of the 
products of combustion. Three holes, each 1 centim. in diameter, in the block admitted 
air to the flame, F. 
The flame thus obtained was steady, and measurements of its conductivity, when a 
particular salt solution was sprayed, did not differ more than 1 or 2 per cent, on 
different days. 
The gas consumed by the flame amounted to 43 litres per hour. The height of 
the inner sharply-defined green cone was 1'5 centim., and that of the outer cone 
7‘5 centims. 
(2.) The Relation between the Current and E.M.F. 
Some experiments were first done on the relation between the current and E.M.F. 
in the flame. The electrodes used each consisted of a brass disk, 14 centims. in 
diameter and 0‘2 centim. thick, having a circular hole 5'6 centims. in diameter at its 
centre, covered with a grating of platinum wires (see fig. 2). 
These two disks were each supported by three glass rods horizontally one above 
the other symmetrically about the axis of the flame. Two parallel slots were cut on 
each side of the hole in the upper disk, and through these the platinum gauze was 
