Batavian Tears

Most likely, such glass drops were known to glassblowers from time immemorial, but they attracted the attention of scientists rather late: sometime in the middle of the 17th century ^[4] . They appeared in Europe (according to different sources, in Holland , Denmark or Germany ). Prince Rupert of Palatinate brought them to England . The technology of making the "tears" was kept secret, but in fact it turned out to be very simple.

If you drop molten glass into cold water, you get a drop in the shape of a tadpole, with a long, curved tail. At the same time, the drop has exceptional strength : you can beat it on its “head” with a hammer and it will not break. But if the tail is broken, the drop instantly shatters into small pieces ^[2] . The experience must be carried out in protective glasses, since the “exploding” glass is very dangerous.

On the frames recorded using high-speed shooting , it can be seen that the front of the “explosion” moves drop by drop at high speed: 1.2 km / s (for comparison: the speed of sound in air is 0.34 km / s , the detonation speed of explosives is 2— 9 km / s ). If the experiment is carried out in the dark, triboluminescence is also noticeable .

In polarized light, it can be seen that the drop is not isotropic , but undergoes strong internal stresses, which causes such strange properties.

Molten glass does not crystallize when the temperature decreases, but goes into a glassy state , that is, the atoms of hardening glass do not have time to take their “correct” places like in the crystal , but form a structure similar to the structure of a liquid . It is important to note that the characteristics of glass in this state — in particular, volume — substantially depend on the cooling rate of the melt ^[5] .

When a drop of glass melted at a temperature of 400–600 ° C falls into water, its outer layer cools so quickly that the glass structure does not have time to change, and the corresponding change (decrease) in volume is small. On the other hand, the core of the drop cools slowly, and therefore the structure of the core glass changes to a much greater degree than that of the glass in the outer layer. However, the volume of the core cannot change according to the change in structure, since the outer layer impedes such a change in volume. As a result, the core is stretched , and the outer layer is compressed . In other words, in the inner part of the cooled drop there are mechanical tensile stresses, and in the outer part - compressive stresses ^{[6] [7]} . The compressed shell is very durable (for example, the bottoms of aerosol cans or concrete tunnels of the metro are also arranged, for example, but if the shell is destroyed, all stresses are released and the drop explodes.

In a similar way, tempered glass is obtained - however, it does not have that tail for which the shell can be broken (more precisely, such “tails” are the corners with the greatest curvature). If, however, the shell can be broken (for example, by inserting a glass of such glass into another glass and heating it, or by hitting the end of a sheet of such glass), the same “explosion” is possible.

• Pele's Tears
• Strained glass
• Triplex

• Trankovsky .C. Batavian tears // Science and life. - 2006. - № 2 .
• Leenson, I. A. Entertaining Chemistry: for 8-11 grades . - Directmedia, 2014. - p. 202-204. - 320 s. - ISBN 5445846229 .
• Johann Beckmann. A History of Inventions, Discoveries, and Origins . - HG Bohn, 1846. - Vol. 2. - P. 241-245.

• The mystery of Prince Rupert’s glass tears is revealed // lenta.ru, May 10, 2017
• Mystery of Prince Rupert's Drop at 130,000 fps (video) (Eng.) . The appeal date is July 6, 2016.
• Prince Rupert's Drop . Corning Museum of Glass. The appeal date is July 6, 2016.
• An interesting property of the Prince Rupert drop (Undec.) . The appeal date is July 6, 2016.
• Bullet vs Prince Rupert's Drop at 150,000 fps (video) (Eng.) . The appeal date is December 29, 2016.