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VII. On the Stratifications in Electrical Discharges^ as observed in Torricellian and other 
Vacua. — Second Communication. By John P. Gassiot, V.P.R.S. 
Eeceived December 9, 1858, — Eead January 13, 1859. 
60. In my former communication I stated that I had obtained several vacua tubes from 
M. Geisslee of Bonn ; shortly afterwards I had the pleasure of a visit from M. Pluckee, 
the distinguished Professor of Physics in that University, when I ascertained that the 
experiments to which I referred as having been made in Germany, had been made by 
that gentleman in vacua-tubes constructed by M. Geisslee. 
During Professor Pluckee’s visit to this country, I witnessed, in the laboratory of the 
Koyal Institution, his experiments on the action of a powerful electro-magnet on the 
negative luminous discharges from an inductive coil, which discharges in vacuo., under 
the influence of the magnet, “coincide in their direction with magnetic curves*;” this 
phenomenon is very clearly shown in Geisslee’s tubes, in which the wires are herme- 
tically sealed at the extreme ends, projecting in a straight direction along the tube. 
Through the kindness of Mr. J. J. Geipfin, I had the opportunity of experimenting with 
upwards of sixty of Geisslee’s vacua-tubes, in which many beautiful and novel results 
are produced ; in some, for several seconds after the discharges had ceased, the tubes 
remained throughout their entire length highly phosphorescent. I have not been able to 
ascertain with accuracy what is the gas, which, however attenuated, must remain in each 
tube ; but from most of them being constructed of a varied form, the discharge presents 
in the several portions of the same tube an entirely difierent appearance, not only in 
colour, but also in the form of the stratiflcations. 
61. As I was desirous, dmlng the progress of the experimental research I had entered 
on, to know the exact conditions under which each vacuum was obtained, and found, by 
comparison, that there was some uncertainty in the description of those I had received 
from M, Geisslee, I reluctantly laid them aside, and for all the experiments I have to 
describe in this communication, each tube was charged and exhausted by myself or in 
my presence. The tubes were constructed by M. Casella, and marked with consecutive 
numbers, a note being taken of each as it was finally sealed; considerably above 100 
were prepared, the major part similar in their form to those described in my former- 
paper f; some of these, during experiment, were broken or otherwise destroyed, but 
* A translation of Professor PiitioKEE’s paper “ On the Action of the Magnet upon the Electrical Dis- 
charge in Earefied Gases,” has since been published in the Philosophical Magazine for August 1858. 
t Philosophical Transactions, 1858, PI. I. fig. 3. 
MDCCCLIX. U 
