Chronos, I understand your explanation, but what I don’t understand is why you even bring gases (by which, flex, he means O2(g) and H2(g)) into the picture.
The formula of water is H2O. That’s two parts hidrogens, one part oxygen. This does not take into account how the molecule was “built” (hey, a particular water molecule exists only for a short time as the atoms rearrange around; a particular one could come from dehydration of a molecule of alcohol and five minutes later that O and those two Hs could be centimeters apart). It does not consider the weight or the volume of the components… it does not consider that most water in a glass will be strung up with others because of the hydrogen bonds, nor that some of it will be dissociated in H+ (sometimes written as H3O+) and OH-. Those details are irrelevant to the issue at hand and irrelevant to a lot of the chemistry of water.
flex, Chronos was talking about the recipe to cook water. Of which there are many, and only mixing 2 H2(g) + O2 (g) —> 2 H2O (out of those many recipes) are you mixing “two parts in volume of hydrogen plus one part in volume of water.” For that same recipe, the “parts in weight” are not 2:1.
The first formulation of an atomic theory is from Democritus. He figured that, as wild as it sounded, having more than four elements and having each element formed of “undivisable” (a-tom) particles which could combine with those of other elements to make compounds made more sense than the other theories floating around at the time. But he didn’t have the means to do experimental research on this. While there were troglodytes fighting this until the early 1900, there were also people who had accepted the notion of “many elements” and were actively looking for more of them in the 1600.