:304 Dr. D. N. Mallik on 



forced vibrations be appealed to. The late Lord Rayleigh, 

 in a letter to 'Nature' (May 21, 1918) questions the 

 possibility of sound-frequencies of 256 vibrations per second 

 being directly conveyed by the nerves to the brain. " It is 

 rather difficult to believe it," he adds, " especially when we 

 remember that frequencies to 10,000 per sec. have to be 



■ dealt with. Even if we could accept this, how deal with 

 light-processes in action along the nerve repeated 10 15 times 

 per second^? " 



I have received kind help from many friends. At the 

 time of my pre-war experiments Professor John Mallet Purser 

 gave me much valuable instruction, and since has continually 

 assisted me. Prof. H. H. Dixon, Dr. O'Sullivan, S.F.T.C.D., 

 and the late Sir Henry Thompson also advised me. More 



/recently, I have to acknowledge much assistance in pxperi- 

 mental work from Prof. Pringle and his Assistant, Dr. Fearon. 

 Dr. Euphan Maxwell has been so good as to place valuable 

 histological specimens at my disposal. I owe much to my 



• discussions with Mr. J. H. J. Poole. 



Trinity College, Dublin. 

 Jan. 4, 1921. 



XXVII. Electric Discharge in Hydrogen. 

 By Dr. D. X. Mallik, F.R.S.E* 



THE peculiar behaviour of an electric discharge through 

 Hydrogen has been the subject of study for a long- 

 time. Tuat it is somewhat erratic, for reasons which are 

 altogether obscure, has been noticed by several experimenters. 

 In particular, in a paper in the 'Philosophical Transactions'' 

 published as long a<^o as June 1907, Prof. H. A. Wilson and 

 Mr. Martyn described the peculiar behaviour of discharge 

 through hydrogen in a De La Rive tube. They found that 

 the rotation effects were not at all well marked when the 

 contained gas was hydrogen ; although when the tube was 

 filled with air or X 2 0, the phenomenon was well defined and 

 capable of quantitative measurement. Working with an 

 induction-coil, as well as storage cells and a tube which had 

 given satisfactory results with several other gases and vapours, 

 I was unable to detect any rotation at all with hydrogen. 

 I was, accordingly, at first disposed to regard this as an illus- 

 tration of the generally erratic behaviour of hydrogen, which 

 previous experimenters had remarked upon. 



* Communicated by the Author. 



