Germania Glasses: The System Na 2 O–CaO–GeO 2

The physical properties of some Na 2 O‐CaO‐GeO 2 and Na 2 O‐CaO‐SiO 2 glasses were compared. The glasses were compounded on a molecular basis with the RO 2 held constant. Physical properties determined were softening point, viscosity, annealing point, density, and refractive index. The possible constitution of these glasses is discussed in brief on the basis of their physical properties. Their optical and transmissive properties, which were also determined, indicate possible new uses.