190 MESSRS. W. DE LA RUE AND H. W. MULLER ON THE 
regular steady strata being observed with this tube, as shown in 15, fig. 49, 
resembling those seen in tube 129, 55 and 56, fig. 46, at the same pressure. 
It is curious that up to this pressure tube 130 had throughout only given 
agitated discharges, and had shown no signs of distinct well-formed lumi- 
nosities. The only difference between tubes 129 and 130 is that the latter 
has a diameter of 175 inch, or 0725 inch less than that of the former ; it is 32 
inches long, 28 inches between the terminals. The strata were blue, with 
the exception of the first and second from the negative, which, as well 
as the cylindrical glow on and about the negative, were pink. With 
1,000,000 o hms resistance the strata turned pink. It was noticed that on 
first closing the circuit the strata were agitated, but after a while they 
became steady, the tube in the meantime becoming heated. 
104. — Pressure 1*0 m.m., 1316 M, 3600 rod cells, 200,000 ohms resistance in 
circuit, steady blue strata like the three middle ones in 15, fig. 49. With 
1 megohm resistance the strata became pink. 
105. — Pressure O’ 2, 263 M, 2400 cells, C. 0'04686 W, 34 steady blue strata were 
produced, which extended to within inches from the negative, this space 
being dark, see 17, also a, fig. 49. On introducing 200,000 ohms resistance, 
C. 0*00879 W, the strata turned pink and assumed the form 18, fig. 49. 
With 500,000 ohms resistance the number was reduced to 21, and with a 
megohm to 16. The calculated resistance of the tube at the above pressure 
was 22,170 ohms. 
106. — Photographs were taken of the tube, which had been separated from the 
pump and which underwent some changes ; with 3600 cells the strata were 
blue and 61 in number, as represented in fig. 1, Plate 16, which is copied 
from a photograph obtained in 11 seconds. 
107. — With 700,000 ohms resistance in circuit the strata were reduced to 
18, and turned pink. Fig. 2, Plate 16, from a photograph taken in 
90 seconds. 
108. — Subsequently another change occurred in the phenomena of the tube with 
3600 rod cells, the phase being most splendid, and showing 21 double strata 
intensely blue, but with a carmine line between the components.* The tube 
*' Gassiot (Brit. Assoc., 1865 (sect.), p. 15) : “ On the change of form and colour which the stratified 
discharge assumes when a varied resistance is introduced in the circuit of an extended series of the 
voltaic battery.” [4000 cells carbon and amalgamated zinc, in each cell a table-spoonfull (24 c.c.) of 
sulphate of mercury]. The resistance in the circuit was a tube ^ an inch in diameter and 3 feet long, 
filled with water, in which two platinum wires could be inserted to different depths : — 
“ On depressing the wire small crescent-shaped disks of red light are observed to be rapidly produced 
in quick succession from the positive pole. Shortening the resistance one by one disappear at the positive 
until 19 remain ; on still lessening resistance two disks near the negative join together, assuming the 
form of a double convex lens, the side near the negative being of a slight blue tinge, that towards the positive 
