Prince Rupert's drop

In other words, the berg becomes like a huge Prince Rupert's drop, which, as every one knows, is a drop formed by allowing molten glass to fall into cold water.

—At the risk of being thought somewhat ignorant, I beg for enlightenment with regard to the following passage extracted from a late number of Household Words:— "Now the first production of an author, if only three lines long, is usually esteemed as a sort of Prince Rupert's Drop, which is destroyed entirely if a person make on it but a single scratch."

If you, or some of your correspondents, would not think this too trivial a matter to notice, and would inform me what the allusion to "Prince Rupert's Drop" refers to, I should be very much obliged.

As in the toy called Prince Rupert's Drop, a multitude of unassimilated particles are bound together by a master necessity.

But if we try the same experiment on the imaginative painter's work, and break off the merest stem or twig of it, it all goes to pieces like a Prince Rupert's drop.