1 Brands: Tums, Caltrate, and most other brands.  Absorption: Calcium carbonate is alkaline based. It requires extra stomach acid for better absorption, so it is best taken right after meals or with a glass of acidic juice such as orange juice.
Tempered glass is one of two kinds of safety glass regularly used in applications in which standard glass could pose a potential danger. Tempered glass is four to five times stronger than standard glass and does not break into sharp shards when it fails. Tempered glass is manufactured through a process of extreme heating and rapid cooling, making it harder than normal glass.
Larger bits tend to run about half as long due to a slightly different type of cutting action. Drilling in 1/4 glass, being twice as thick, will normally produce only half as many holes over a drill bit's life, if the glass hardness and drilling techniques are the same. Tempered glass has differing degrees of temper, and will reduce drill bit life by 75% to more than 90%, compared to standard glass.