FACTORS INFLUENCING AUTOCLAVE CHEMICAL DURABILITY TESTS OF GLASS CONTAINERS*

To secure reproducible results with the chemical durability test in which distilled water is used as the leaching medium, the distilled water must be prepared with special care because certain impurities, of which copper is the most important, are present in small quantities and exhibit a marked effect on alkalinity values. Other impurities, such as lead, iron, sodium silicate, and sodium carbonate, which may be found occasionally in distilled water, do not have as great an effect as copper on alkalinity values. The temperature at which the leaching is carried out has a much greater effect on the test than the length of the test period.