SolutionsAt the end of the XVIII Century
1. Lavoisier's analyses
Which elements did Lavoisier find in the compounds extracted from plants? And in those of animal origin?
In plants, only carbon, hydrogen and oxygen. In those of animal origin, sometimes nitrogen as well.
2. Few elements, many compounds
Dalton assumed that the formula of a compound had to be the simplest possible (water would be OH). Why did this idea make Organic Chemistry hard to understand?
If each combination of elements could only give the simplest formula, with so few elements (C, H, O and N) there could hardly be different compounds. Yet a great many organic compounds made of those same elements were already known.