John Dalton
Both laws have to do with relating to Dalton's Atomic Theory. The only difference is that the Law of Definite Proportions deals with elements combining to form ONE compound in a simple whole number ratio. The Law of Multiple Proportions is comparing the same 2 elements that make up 2 different compounds, the division of these 2 ratios should equal a simple whole number ratio.
In chemistry, the law of definite proportions, sometimes called Proust's Law, states that a chemical compound always contains exactly the same proportion of elements by mass. An equivalent statement is the law of constant composition, which states that all samples of a given chemical compound have the same elemental composition by mass. For example, oxygen makes up about 8/9 of the mass of any sample of pure water, while hydrogen makes up the remaining 1/9 of the mass. Along with the law of multiple proportions, the law of definite proportions forms the basis of stoichiometry.
In chemistry, the law of definite proportions, sometimes called Proust's Law, states that a chemical compound always contains exactly the same proportion of elements by mass. An equivalent statement is the law of constant composition, which states that all samples of a given chemical compound have the same elemental composition by mass. For example, oxygen makes up about 8/9 of the mass of any sample of pure water, while hydrogen makes up the remaining 1/9 of the mass. Along with the law of multiple proportions, the law of definite proportions forms the basis of stoichiometry.
Dalton's fourth postulate states that atoms combine in simple whole-number ratios to form compounds. This postulate laid the foundation for the law of definite proportions and the law of multiple proportions in chemical reactions and helped in the development of modern atomic theory.
The Law of Definite Proportions was discovered by Joseph Louis Proust in the late 18th century. He observed that compounds always contain the same elements in the same proportion by mass.
Boyle's Law
It was God who "came up with" the Torah, not the Hebrews.
newton
If the mass proportions of the original substances do not equal these definite proportions, there will something of one of the original substances be left over. Note that this is special, it could as well have turned out to be possible for substances to combine in any proportion. So we find the law of definite proportions. Now we should be baffled and wonder how on Earth could that be so? And then we could think of substances being made of small particles (atoms) or groups of such particles (molecules) to explain the laws of nature that we found. So the laws of definite proportions and multiple proportions are (partially) proof for the existence of atoms which combine into molecules. The laws are the real thing and atoms and molecules and their chemical formulas are the ideas we make to understand the laws.
This is an old rule (Law of definite proportions) not valid for nonstoichiometric compounds.
Wilhelm Wien