Shape
Beakers are often graduated, that is, marked on the side with lines indicating the volume contained. For instance, a 250 mL beaker might be marked with lines to indicate 50, 100, 150, 200, and 250 mL of volume. These marks are not intended for obtaining a precise measurement of volume (a graduated cylinder or a volumetric flask would be a more appropriate instrument for such a task), but rather an estimation.
The presence of a lip means that the beaker cannot have a lid. However, when in use, beakers may be covered by a watch glass to prevent contamination or loss of the contents, but allowing venting via the spout. Alternatively, a beaker may be covered with another larger beaker that has been inverted, though a watch glass is preferable.
Read more about this topic: Beaker (glassware)
Famous quotes containing the word shape:
“I used to say: “there is a God-shaped hole in me.” For a long time I stressed the absence, the hole. Now I find it is the shape which has become more important.”
—Salman Rushdie (b. 1948)
“But virtue, as it never will be moved,
Though lewdness court it in a shape of heaven,
So lust, though to a radiant angel linked,
Will sate itself in a celestial bed
And prey on garbage.”
—William Shakespeare (1564–1616)
“I know that each stage is not going to last forever. I used to think that when he was little. Whenever he was in a bad stage I thought that he was going to be like that for the rest of his life and that I’d better do something to shape him up. When he was in a good state, I thought he was going to be a perfect child and I would never have to worry; he was always going to stay that way.”
—Anonymous Parent of An Eight-Year-Old. As quoted in Between Generations by Ellen Galinsky, ch. 4 (1981)