Flask, round-bottom star cracks

Round-Bottom Flasks, Pennyhead Stoppers, Plugs, and Other Loose Items. Many items are stored in drawers and (as the drawer is opened and closed) can bang around. This situation applies especially to round-bottom flasks, which are hard to prevent from rolling around. When these flasks bang around, star cracks, or flaws for future fracture, are created. For round-bottom flasks, Erlenmeyer... 

Placing a wire gauze between the flame and the flask spreads out the heat evenly. Even so, the burner may have to be moved around. Hot spots can cause star cracks to appear in the flask (see Chapter 4, Round-Bottom... 

Examine your glassware for cracks and other weaknesses before assembling the distillation apparatus. Look for "star cracks in round-bottom flasks, because these can cause a flask to break upon heating. 

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