Possible Clues:

• Scientist of yesteryear with regret, looking back
• Louis who developed a rabies vaccine
• He invented a method to stop milk causing disease
• Old political grouping assembled by King Louis
• Chemist tears up letters
• Historic plant raised for chemist
• Chemist shortened way to get straight to website?
• Louis —, French chemist and microbiologist
• He developed the partial sterilization of milk
• Chemist, one sticking around university