TRIPLE POINTS OF e-H2, Ne, O2. AND Ar: 3.2.2 TRIPLE POINTS OF e-H2, Ne, O2. AND Ar 3.2.2.1 GENERAL CONSIDERATION OF APPARATUS DESIGN The cryogenic fixed points (triple-points of pure gases equilibrium hydrogen, natural neon, oxygen, and argon) are best real ed in a calorimetric type apparatu