400 
DR. F. P. BURT AND DR. E. C. EDGAR ON 
whether oxygen was made by heating this tube or one of the other four. The mouths 
of the five tubes were plugged with carefully cleaned glass wool. 
From the generating tubes the oxygen passed through a series of three washing 
towers filled with glass beads. 
The first tower, F, contained a moderately strong solution of caustic potash ; the 
second, G, a saturated solution of barium hydroxide. The column of liquid in each 
tower was over a metre in height. Between the barium hydroxide tower and the 
next washing vessel a manometer, H, was attached to the train. The short tower, J, 
F G 
contained a stronger solution of potash, and the U-tube, K, a very concentrated 
potash solution on pumice that had previously been heated in a stream of oxygen. 
From the U-tube, K, the gas passed through two tubes, L, L, containing sticks of 
caustic potash, and finally through two tubes, M, M, containing phosphoric oxide. 
The object of the two large alkaline towers was to retain oxides of manganese and 
carbon dioxide. The two tubes, J and Iv, containing potash of increasing concentra¬ 
tion, served to diminish distillation of water from the towers to the stick potash 
tubes. After the apparatus had been in use for more than two years there was no 
sign of deliquescence either in the solid potash or in the phosphoric oxide. 
