Possible Clues:

• Talk drugs, mustard and marsh, say?
• Eg, neon, oxygen, etc
• Neon and argon
• Helium and oxygen, for two
• Air-like substances
• Natters (informal)
• Six of the first 10 elements on the periodic table
• Atmosphere, essentially
• Elements No. 7, 8, 9 and 10, e.g
• Elements that make up the atmosphere