My chemistry teacher loves going back through the history of famous chemists. This got me wondering how these chemists would first determine the concentration of a sample before they had any other chemicals of known concentration to compare against?
What modern methods are there for determining concentrations and purity without other chemical standards to compare against?
Let me explain my question a little more clearly with an example.
If a historical scientist starts their own laboratory and wanted to do a titration, how would they start? They might produce some hydrochloric acid, or some barium sulfate, and want to confirm its concentration/purity. However, this would require they already know the concentration of something else, which they don't. So it seems a little paradoxical. How did they ever start performing analytical experiments?