Intelligence and Miscellaneous Articles. 299 



sulphuric acid ; from all parts of the immersed platinum wires gas- 

 bubbles are seen to rise. The positive wire furnishes oxygen, the 

 positive liquid surface hydrogen; and it is the reverse at the 

 negative side. Various other examples can be cited in proof that 

 a dividing surface between a liquid and a gas may be regarded as 

 an electrode. This view receives especial confirmation from the 

 phenomena of occlusion *. If, namely, the current has passed 

 through for a long time, one induction-shock in the same direction 

 furnishes distinct gas-bubbles ; if now the current be reversed, 7-9 

 induction-shocks will be necessary at the electrode charged with 

 oxygen before the gas-bubbles are observed, while at that charged 

 with hydrogen certainly 15-17 will be required. 



When the electrolytic process was continued during a whole 

 week, predominantly oxygen only was obtained in the tube. Pri- 

 marily, however, both oxygen and hydrogen are always separated ; 

 but the latter finally precipitates sulphur from the sulphuric acid, 

 which at first makes the liquid thick, and then settles to the 

 bottom. 



In order to decipher and explain the complex spectrum, I was 

 obliged to carry out two new operations — to produce a pure oxygen- 

 spectrum, and to determine the conductivity of the pure gases 

 oxygen, hydrogen, nitrogen. I permit myself here only to report 

 upon the oxygen-spectrum, reserving for subsequent communica- 

 tions the conductivity of the gases mentioned. 



In the tube there might be contained nitrogen, hydrogen, oxygen, 

 mercury-vapour. On the spectrum of oxygen the most diverse 

 results have been given by Pliicker (Pogg. Ann. cvii. p. 497), 

 Wullner (Pogg. Ann. cxxxv. p. 377), Salet {Ann. d. Chim. [4] 

 xxviii. p. 5), Yogel (Pogg. Ann. cxlvi. p. 569), Huggins (Phil. 

 Trans, cliv. p. 139), Pliicker and Hittorff (Phil. Trans, civ. p. 1), 

 and Schuster (Proc. Boy. Soc. xxvii. p. 383). 



The tubes for examination I filled with oxygen : — (1) after the 

 method previously described, by decomposition of the concentrated 

 sulphuric acid by the induction-current, when finally oxygen was 

 almost solely evolved ; (2) by fusing to the experiment-tube a 

 voltameter containing concentrated sulphuric acid, six Bunsen cells 

 being employed for the decomposition ; (3) by heating chlorate of 

 potass in a retort united directly to the tube by fusion. 



I was at length obliged to abandon the use of a gasometer and 

 any other drying-apparatus than that attached to the air-pump, 

 containing solid phosphoric acid, since they never furnished pure 

 results. 



Tightening the stoppers and cocks with tallow, caoutchouc, or 

 concentrated sulphuric acid gave the same results. 



The filling and exhaustion of the vessels and pump were of course 

 repeated until the phenomena became constant — most frequently 

 from 40 to 50 times t. 



I have always found only one oxygen-spectrum, consisting of 



* Helmholtz, Pogg. Ann. cl. p. 483. 



t I made use of the appearance of the intensely green fluorescence-light of 

 glass as a sign that the exhaustion of the tubes was as complete as possible. 



