436 RIESS ON THE INCANDESCENCE OF 
APPEARANCES WHICH PRECEDE AND ACCOMPANY THE 
HEATING TO REDNESS. 
Vibration—Vaporization. 
The battery which I used consisted of five jars, each of which 
contained a covered surface of one and a half cubic feet; it 
would not however bear the charge which was necessary for 
many of the following experiments: I therefore changed it for 
one consisting of seven jars, each containing 2°6 cubic feet of 
coated surface. These jars stand upon a wooden frame 27 in. 
in diameter, insulated by glass feet, and covered with tin foil; 
they are supplied with f-shaped pieces of metal in contact with 
their interior surfaces, and moveable on hinges, by means of 
which any number of them can be brought into connexion with 
each other. The unit jar, by means of which the charge of the 
battery was measured, had, as before, half a cubic inch of covered 
surface; its balls were also at half a line distance from each 
other, but I now took as unity the quantity of electricity causing 
two explosions. This unity is in future also understood for 
those experiments which were made with the old battery, in 
which case the number of jars will be denoted by an asterisk. 
A platina wire, 34 lines in length and 0:0209 line radius, was 
inserted by means of two strong springs of bell-metal in the 
connecting circuit of the battery. On the discharge of increa- 
sing quantities of electricity the following appearances were ob- 
served in the wire. 
Experiment 1. 
Number Quantity of 
of jars. electricity. 
4* 5 The wire vibrates violently. 
7 A streak of vapour rises from it. 
9 No vapour—slight bend in the wire. 
11 The bend increased and a new one formed. 
13 The wire is red-hot and bent in many 
places. 
15 The wire is white-hot, with so many 
bends as to be tightly stretched. 
Experiment 2.—Another platina wire, 16 lines in length and 
with a radius of 0°0261, gave the following signs :— 
