Prince Rupert's drop

The drops are named after Prince Rupert of the Rhine, who brought them to England in 1660, although they were reportedly being produced in the Netherlands earlier in the 17th century and had probably been known to glassmakers for much longer.

They were studied as scientific curiosities by the Royal Society, and the unraveling of the principles of their unusual properties probably led to the development of the process for the production of toughened glass, patented in 1874.

The high fracture toughness due to residual compressive stresses makes Prince Rupert's drops one of the earliest examples of toughened glass.

The Dutch scientist Constantijn Huygens asked Margaret Cavendish, Duchess of Newcastle to investigate the properties of the drops; her opinion after carrying out experiments was that a small amount of volatile liquid was trapped inside.

He gave them to King Charles II, who in turn delivered them in 1661 to the Royal Society (which had been created the previous year) for scientific study.

[4] His publication laid out correctly most of what can be said about Prince Rupert's drops—without a fuller understanding than existed at the time of elasticity (to which Hooke himself later contributed), and of the failure of brittle materials from the propagation of cracks.

[13] In 1994, Srinivasan Chandrasekar, an engineering professor at Purdue University, and Munawar Chaudhri, head of the materials group at the University of Cambridge, used high-speed framing photography to observe the drop-shattering process and concluded that while the surface of the drops experiences highly compressive stresses, the inside experiences high tension forces, creating a state of unequal equilibrium which can easily be disturbed by breaking the tail.

This gives the surface a high fracture strength, which means it is necessary to create a crack that enters the interior tension zone to break the droplet.

In his 1943 novella Conjure Wife, Fritz Leiber uses Prince Rupert drops as a metaphor for the volatility of several characters' personalities.

The title-giving suite to progressive rock band King Crimson's 1970 third studio album Lizard includes both parts referring to a fictionalised version of Prince Rupert as well as an extended section called "The Battle of Glass Tears".