ABSTRACT
The study of the discharge of electricity from glowing bodies is so closely associated with the ionisation of gases that it will be advisable to refer briefly to some of the effects of ionisation. Ionised gas may be produced in a variety of way, by the application of X-rays, cathode rays, high temperatures or ultra-violet light. A good illustration of ionisation is formed by placing two platinum wires forming the terminals of a battery in different parts of a Bunsen flame. The flame itself, being an ionised gas, permits an appreciable current to flow, and this current can be further increased by the addition of potassium or sodium salts to the flame. The effect of high temperatures in producing ionisation can be readily explored by surrounding a platinum wire by a metal cylinder, so as to form a condenser in vacuo.
