Separating Glass by Type

Typically, only a few commercial soft glass items may work their way into a research lab. Such items as student ware graduated cylinders or burettes are readily identifiable, and since these items shouldn t be heated, are unlikely to cause damage. Specialized or custom made glassware may not be as easily identifiable and therefore may require some analysis. 

Glass Type Thermal Coefficient of Expansion (0-300°C) xlO 7 Acm/cm/°C Strain Pont (=°C) Annealing Point (-°C) Softening Point ( °C) Working Point ( °C) Density (g/cm2) Refractive Index 

Glassware that has bends and/or has been fused to other pieces of glass will be either common laboratory borosilicate glass or fused silica. Any soft glass made into laboratory apparatus is for special application or, more likely is very old (and ought to be in a museum). 

Sighting Down the End of a Glass Tube or Rod (Nondestructive). Even though most glasses will look the same when observed from the side, looking at 

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  

---