The Law of Multiple Proportions states:

“When two elements combine to form two or more chemical compounds, the ratio between different weights of one of the elements which combine with a fixed weight of the other is always simple.” Examples:

- Compound of Carbon and Oxygen : C and O combine to form two compounds CO and C${{O}_{2}}$.

In CO, 12 parts by wt. of C combine with 16 parts by wt. of O.

In CO2,12 parts by wt. of C combine with 32 parts by wt. of O.

If the weight of C is fixed at 12 parts of wt. then the ratio in the weights of oxgyen which combine with the fixed wt. of C (= 12) is 16 : 32 or 1:2.

Thus the weights of oxygen bear a simple ratio of 1 : 2 to each other. 2 - Compounds of Sulphur (S) and oxygen (O):

S forms two oxides with O, viz. S${{O}*{2}}$ and S${{O}*{3}}$

In S${{O}*{2}}$,32 parts by wt. of S combine with 32 parts by wt. of O.*{3}}$, 32 parts by wt. of S combine with 48 parts by wt. of O.

In S${{O}

If the wt. of S is fixed at 32 parts, then the ratio in the weights of oxygen which combine with the fixed wt.

of S is 32:48 or 2 : 3.

Thus the weights of oxygen bear a simple ratio of 2 : 3 to each other