178 PROFESSOR H. B. DIXON AND MR. E. C. EDGAR 



The arrangement of the apparatus is shown in fig. 3. A was the U-tube of Jena 

 glass, having two delivery tubes B and B t which united at C ; its capacity was such 

 as to'admit of the fusion of 800 grammes of silver chloride introduced through the 

 side tube F. The carbon electrodes D and D 1} of 2 millims. diameter, were specially 

 made for us by the Acheson Graphite Company, Niagara. Before being fixed in 

 position they were heated to redness for twelve hours in a current of chlorine, and 



Fig. 3. Chlorine apparatus. 



were then kept in vacuo in a porcelain tube for three hours at a bright red heat. 

 A special glass joint at G permitted the junction of the U-tube to the other portion 

 of the apparatus, which was constructed of soft glass. This joint was made by fusing 

 together a series of twelve very short pieces of tubing which varied by small 

 gradations from hard Jena to soft glass. H was a small drying tube containing pure 

 phosphorus pentoxide, which was kept in position by two plugs of clean glass-wool. 

 K was a glass tube (capacity 25 cub. centime.) in which a sample of the prepared 

 chlorine could be collected to test its purity. L was a T-piece, one limb of which 

 was fused to the chlorine generator ; another led, via the absorption tubes M and N, 

 to the mercury pump, whilst the third was fused to the " chlorine bulb." 



To prevent any residual chlorine reaching the pump, it was passed through the 

 tube M (which could be filled with mercury to a suitable height by raising a 

 reservoir), and then through a tube N, 1 metre in length and 4 centims. in diameter, 

 packed closely with pure potassium hydrate. A little mercury, contained in the 

 cavity 0, acted as a tenioin. The dulling of its bright surface would have indicated 



