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VIII. Experimental Researches on the Electric Discharge with the Chloride of 
Silver Battery * 
By Warren De La Bue, M.A., D.C.L., F.R.S., and Hugo W. Muller, Ph.D,, F.R.S. 
Received April 10, — Read May 16, 1878. 
[Plates 15-18.] 
Part II.— THE DISCHARGE IN EXHAUSTED TUBES. 
We cannot flatter ourselves that we have done more during our three-and-a-half 
years’ work than contribute a few facts towards the data necessary for the solution of 
the problem, “ What is the cause of the beautiful phenomenon of stratification produced 
by electric discharges in vacuum tubes ? ” which, having been first noticed by M. Abria 
in 1843, was independently re-observed by Mr. (now Sir William) Grove in 1852, t 
* These researches have been prosecuted independently and without the knowledge of much that has 
been done by other workers in the same field. Subsequently to the communication of this memoir we 
have diligently searched the papers of other physicists, and have extracted from them many interesting 
passages which, by permission of the Council of the Royal Society, we have added in the form of foot- 
notes at various parts of the paper. As it is quite possible that some papers may have escaped our notice, 
a list of those consulted is given in the Appendix, note A. 
Mascart, in his valuable 1 Traite d’Electricite Statique,’ t. ii., pp. 128-141, 1876, has given a succinct 
account of the phenomena of the discharge in vacuum tubes, and the various hypotheses which have 
been proposed to account for them. 
f Gassiot (Bakerian Lecture, Phil. Trans., 1858, pp. 1-16) gives the following history of the 
stratified discharge : — 
“ The striated condition of the electric discharge in vacuo which takes place when the terminal 
wires are inserted in a well exhausted receiver in which a small piece of phosphorus has been previously 
placed, was first announced by Mr. Grove in his communication to the Royal Society, 7th January, 1852 ; 
his paper is printed in the first part of the Transactions for that year, and was subsequently published in 
the Phil. Mag., December, 1852, with a supplementary note, dated 9th June, wherein Mr. Grove states 
‘ that he found the transverse dark bands could be produced in other gases when much attenuated, 
probably in all.’ 
“ The phenomena of stratification in the discharge in vacuo were subsequently observed in Paris by 
Rtjhmkorff, who obtained the effect by using the vapour of alcohol ; they were again noticed by 
Masson, Du Moncel, Quet, and other continental electricians, who all describe the intense white light 
without stratification produced in the barometrical vacuum.” 
It appears, however, that Grove was anticipated by Abria (Ann. de Chim. vii., 1843, pp. 477-478), 
who, experimenting with the secondary current of an induction coil, obtained in air at a pressure of 2 m.m., 
in an exhausted receiver, a brush-discharge from the positive (a ball) which did not quite reach the 
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