Subject
- Pennsalt Chemicals Corporation1
- Pennsylvania--Philadelphia--Bridesburg1
- Perfumes industry2
- Perkin, William Henry, Sir, 1838-19071
- Perkin-Elmer Corporation2
- Pesticides1
- Pests--Control1
- Pharmaceutical industry1
- Pharmacognosy1
- Phlebotomy2
- Photomicrography1
- Photomicrography--Equipment and supplies1
- Physical instruments1
- Physiology1
- Plants1
- Plastics1
- Plastics industry and trade3
- Pneumatics1
- Pocket calculators1
- Poisons1