Law of Multiple Proportions – when two elements form a series of compounds, the ratios of the masses of the second element that combine with mass of the first element can always be reduced to small whole numbers.
Dalton (1766-1844) discovered that carbon and oxygen form two different compounds that contain different relative amounts of carbon and oxygen.
Cathode-Ray Tube – a high voltage applied to a tube produced a ray (cathode ray). The ray was produced at the negative electrode and was repelled by the negative pole of an applied electric current. Thomson (1898-1903) concluded that the ray was a stream of negatively charged particles.
Deflection of Cathode Rays by an Applied Electric Field