ELECTRIC DISCHARGE WITH THE CHLORIDE OF SILVER BATTERY. 
69 
July 5th.—11,000 cells, short-circuit, deflection 51°, total battery-resistance 
= 336,200 ohms. 
Pressure. 
Deflection with 
tube. 
Total resistance. 
T ub e -r esis t an ce. 
Tube-potential 
V. 
m.m. 
M. 
ring - 
ohms. 
ohms. 
cells. 
1-023 
1346 
47-0 
386,700 
50,500 
1436 
0-822 
1082 
50'0 
348,500 
12,300 
388 
0-642 
845 
47-0 
386,700 
50,500 
1436 
0-421 
554 
47-0 
386,700 
50,500 
1436 
0-341 
449 
46-0 
400,300 
64,100 
1762 
0-265 
349 
47-0 
386,700 
50,500 
1436 
0-169 
222 
49-0 
360,800 
24,600 
750 
0-096 
126 
47-0 
386,700 
50,500 
1436 
0-076 
100 
45'0 
415,000 
78,800 
2088 
0-046 
61 
44-0 
430,700 
94,500 
2415 
The observations point clearly to the resistance of a tube diminishing as the 
pressure decreases up to a certain point, after which it rapidly increases ; the pressure 
of least resistance in the case of hydrogen, as shown by the experiments when the 
ring was positive, being about 0'642 m.m., 845 M. The resistance increases very 
rapidly when a pressure of 0'0076 m.m., 10 M, is reached, and the curve then becomes 
nearly a vertical to the abscissas. At a pressure of 0‘002 m.m., 3 M, the discharge of 
11,000 cells only just passed. (Part II., page 187, footnote.) 
With a pressure of 0 - 0ul37 m.m., 1'8 M, 11,000 cells would not pass, and with a 
pressure of 0'000055 m.m., 0'066 M, even a 1-inch spark from an induction coil would 
not pass. (Part II., page 215.) 
The diagram (fig. 71) laid down from the results when the ring was made positive, 
shows the curve of the observations as actually obtained without being smoothed. The 
figure is a reduction to 3k of the original; the abscissae are as the cube-roots of the 
various pressures in millionths of an atmosphere, and show relatively the number of 
molecules in a given linear space, the ordinates are as the number of cells. 
The life of the battery is so much exhausted by such a series of experiments, in 
consequence of the length of time the current has to remain on while the galvano¬ 
meter becomes steady, that it was not deemed desirable to extend them to other 
gases or to repeat the experiments in order to obtain an average smoother curve for 
hydrogen. There is, however, no reason to doubt the accuracy of the results as 
recorded at the moment of each experiment, for the character of a tube is continually 
altering during a continuous series of experiments, and 110 precautions can be taken 
which will render a tube absolutely constant for any length of time. In order to 
avoid running down the battery, other methods for determining the tube-potential 
were subsequently adopted; these are described in notes A and B in the Appendix. 
When the observations with the ring positive were laid down with the abscissae 
representing millionths (not their cube-roots) in order to extend the scale, and a smooth 
