218 LORD RAYLEIGH AND PROFESSOR W. RAMSAY ON ARGON, 
convenient apparatus for large-scale operations that has hitherto been tried is shown 
in the accompanying figure (fig. 7). 
The vessel A is a large globe of about 6 litres capacity, intended for demonstrating 
the combustion of phosphorus in oxygen gas, and stands in an inclined position. It 
is about half filled with a solution of caustic soda. The neck is fitted with a rubber 
stopper, B, provided with four perforations. Two of these are fitted with tubes, 
C, D, suitable for the supply or withdrawal of gas or liquid. The other two allow 
the passage of the stout glass tubes, E, F, which contain the electrodes. For greater 
security against leakage, the interior of these tubes is charged with water, held in 
place by small corks, and the outer ends are cemented up. The electrodes are formed 
“i 

A } 
% Soda solutt? Wy 
of stout iron wires terminated by thick platinums, G, H, triply folded together, and 
welded at the ends. The lead walls required to enclose the cooling water are 
partially shown at I. For greater security the india-rubber cork is also drowned in 
water, held in place with the aid of sheet-lead. The lower part of the globe is 
occupied by about 3 litres of a 5 per cent. solution of caustic soda, the solution rising 
to within about half-an-inch of the platinum terminals. With this apparatus an 
absorption of 3 litres of mixed gas per hour can be attained,—about 3000 times the 
rate at which CAVENDISH could work. 
When it is desired to stop operations, the feed of air (or of chemical nitrogen in 
blank experiments) is cut off, oxygen alone being supplied as long as any visible 
absorption occurs. Thus at the close the gas space is occupied by argon and oxygen 
with such nitrogen as cannot readily be taken up in a condition of so great dilution. 
