Pyrex® glass, refractive index

Matching the Index of Refraction (Nondestructive). To match the index of refraction for two or more glasses, obtain a liquid with the same index of refraction as one type of glass. When an unknown glass is put into the liquid, the glass will seem to disappear if it has the identical index of refraction. Two standard solutions for identifying Pyrex or Kimex glass (their refractive index is 1.474) are ... 

The experimental facility and instrumentation are shown in Fig. 1. The flow facility consists of a vertical 2.5 cm diameter, 15 cm long Pyrex glass test cell mounted beneath a low-pressure reservoir of volume 0.27 m. The test cell is sealed by an aluminum foil diaphragm, which is ruptured by pneumatically driven knife blades. The test cell is surrounded by a liquid-filled jacket with flat windows. This serves two purposes to eliminate the cylindrical lens effect of the test liquid (by choosing a jacket liquid with a refractive index similar to that of the test liquid) and to provide temperature control (by circulating the jacket liquid through a heat exchanger). 

Fig. 7.12. Two tubes containing Pyrex beads in glass wool and solvent (a) the refractive index of solvent matches that of glass wool and (b) the refractive index of solvent is different from that of glass wool or pyrex beads and scattering from the glass wool dominates. (Reproduced with permission of D. M. Engelman.)...

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