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THE EARL OF BERKELEY, MESSRS. E. G. J. HARTLEY AND C. Y. BURTON: 
water vessel to the sulphuric acid; when it occurs in the other tubes there has 
always been some faulty manipulation or a rapid change in the temperature of the 
bath. 
Apparatus C. It was soon noticed that the soft Jena-glass seemed particularly 
liable to deposition of moisture (possibly this glass is more soluble than others ?) and 
also that cracks were developed in it. Hitherto, it will be recalled, the vessels are 
constructed so that the air enters at the middle of.the first branch and leaves at the 
middle of the last branch ; the stream is thus divided, re-united, divided again and 
then re-united. 
It was thought that possibly better results would be obtained if the air were to 
enter at one end of the first branch, and, travelling along each branch in succession, 
Fig. 4. 
were to leave the vessel at the end of the fourth and last branch. Apparatus C 
was so constructed of ordinary soda-glass, but no apparent gain resulted. 
Apparatus D. Meanwhile a number of experiments were made with a view to 
preventing the deposition of moisture mentioned above. A quartz vessel was 
substituted for the water vessel in Apparatus B and was found to be an improvement, 
so it was decided to make all the vessels of silica glass, the joints being similar to 
fig. 4, with the addition of a silver sleeve D resting on the cone as shown in that 
figure; this sleeve helps to prevent diffusion into the space surrounding the lower 
ends of the inverted U-tubes. 
