Possible Clues:

• How Helmholtz liked being brought chemists' notes and other such principles!
• Weather will be mild, not cold, in centre of Odessa
• Earth, fire and water
• Factors
• 13-book Euclidean treatise
• He and I, perhaps, in key parts
• Nitrogen and oxygen, e.g., make the weather
• Gold and silver, but not bronze
• Earth, wind and fire
• Iron, carbon, and chromium, for example, workers put in sort of steel