Law of Multiple Proportions

This law was proposed by Dalton in 1803. According to it, if two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in the ratio of small whole numbers.

The book's own example: hydrogen combines with oxygen to form two compounds — water and hydrogen peroxide.

Here, the masses of oxygen (16 g and 32 g) which combine with a fixed mass of hydrogen (2 g) bear a simple ratio — 16 : 32, i.e. 1 : 2. …