Doubts regarding the law of reciprocal proportions: What i have understood by reading the definition is that the ratio of the masses in which two elements A and B combine with a fixed mass of a third element C, will be a whole number multiple of the ratio of the masses in which A and B combine with each other. My question is that is order important here? Let A and C combine in the ratio a:c1 and let B and C combine in the ratio b:c2=((b*c1)/c2):c1.(by mass). Then according to the law of reciprocal proportions, a:((b*c1)/c2)=k (a:b) where k ia whole number. If we reverse the order in which we consider the mass of the elements in the ratio, will we get the same result then also? (Is ((b*c1)/c2):a=j (b:a) where j is a whole number in that case also). Doubts regarding equivalent weight:I do understand the definition of equivalent weight but cannot make sense of it and understand the significance of the definition. What is the meaning of "parts by mass" in it's definition and what is the use of equivalent weight?