Is it true that there is a mercury knife that always hits the target with its tip?

On the forums of knife throwing enthusiasts you can often come across a story: there is an army mercury knife in the world, secretly developed in the Soviet Union, and it always hits the target with its tip. We decided to check whether such a knife really exists or is it just an urban legend?

That's what it says on one of the sites dedicated to knives, about the legendary mercury knife, allegedly developed by Soviet intelligence officers:

“According to the stories, there was some kind of secret development either by special forces or spies. It was a throwing knife that always stuck to the target, no matter how it was thrown.

This blade was once developed for counterintelligence officers immediately after the end of the Great Patriotic War. There was a hole in the blade of the knife that was filled with mercury, during the throwing process it moved towards the tip, so the knife always stuck into the target.

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So, in 1940, the first models of Soviet military knives began to appear, and then the designers came up with the idea of ​​​​creating a throwing knife based on an army model. The throwing knives were identical to the production models, the only difference being a slot in the blade to accommodate a mercury capsule. Tungsten communicating sealed capsules were installed into the handle of the knife, into which the required amount of mercury was pumped.”

According to articles talking about the mercury knife, the item appeared immediately after the Great Patriotic War, but was kept completely secret. Nevertheless, his people allegedly met: someone had a neighbor who previously worked in the army who had this knife, someone saw it with a military relative, someone showed drunk friend. All these witnesses, however, saw the knife only once, and then it disappeared: it was lost, it was stolen, and a friend who had sobered up forbade anyone to talk about it.

Most likely, the myth about the existence of a mercury knife appeared in Soviet times, because references to it can already be found in the literature of the 1990s. In his 1993 book “How they fought in the NKVD,” Alexander Medvedev, expert in the field of hand-to-hand combat, casually mentions a certain “special knife”, without citing any sources:

“It [the knife] differs from ordinary ones in that it has a weighted blade towards the tip and a handle in the form of a feather. (In the modern production of such throwing devices, mercury is used.) Such a knife always flies with the blade forward. They throw it at a distance of up to 20 m. The method is typical for the Central Asian region. The throw is made suddenly, from any position, in the most appropriate way, including from a horse at full gallop.”

Later, a similar mercury knife (in the phrase “scout knife”) could be found in other literature of the 1990s. For example, the writer Andrei Konstantinov (especially known for “Gangster Petersburg”) mentioned him in his book “Specialist”.

The mechanism of action of the mercury knife was described in detail in 1996 in his book “Special Operations Forces” by Nikolai Volkovsky, teacher Faculty of Journalism, St. Petersburg State University, defended dissertation on the topic “Journalism in Information Wars”:

“This knife is called a mercury knife because in its body there is a channel (cavity) running along the entire length of the blade and handle, ⅓ filled with mercury. The entire knife, including the handle, is made of metal. The air from the channel is pumped out, and the mercury is in a vacuum. Throwing it is done by grabbing the handle from behind the head with the blade forward. At the moment the knife is lifted from the hand (the end of the external force acting on it), the mercury has the highest speed and, continuing by inertia to move along the channel, after a split second it reaches the opposite side of the channel (at the tip). At the moment of contact of mercury with the bottom of the channel, a hydraulic shock occurs, and the knife, trembling, takes a stabilized flight path: with the tip forward until it contacts the target.”

In theory, a mercury knife could exist from a physics point of view. Mercury in the handle would be needed in order to shift the center of gravity and prevent the knife from rotating. Likewise works water bottle trick: if you throw a bottle about 30% full of water while spinning, it will make one revolution, land on the bottom and remain standing. This also works by shifting the center of gravity.

However, knife throwers note, that in reality the strength of the knife also affects the result of the throw. If there is a hollow channel inside to move the mercury, it will most likely not be the highest. In the legend, the blade of a mercury knife has a classic shape, and such a knife will most likely turn out to be too fragile, think skeptics. And if you make the cavity too small, then to stabilize the center of gravity of mercury Maybe It's just not enough.

Today, most bladed weapon lovers are still skeptical about the legend of the mercury knife. Memes are made on this topic, people laugh at the fact that no one has evidence of the existence of a knife. Although new publications continue to be published.

For example, there was a story about modern mercury knives - a development called Hydrargyrum-Knife-999-Hg. According to the anonymous narrator, in 2004 he met a certain Yegor at the advanced training courses at the Academy of the Ministry of Internal Affairs of Russia, who also came to study. He had a secret mercury knife of a new model with him. After drinking, he decided to show it, and the narrator himself allegedly took photographs on an “old phone.” 

At the end of the story the author speaksthat it's been almost ten years, so he decided to share the story. True, the story itself walked on the Internet already in 2011, just six years after the alleged events.

In 2020, the myth about this development exposed portal rezat.ru. The authors examined photographs allegedly taken by the narrator on an “old phone” in 2004 (by the way, their quality is suspiciously high), and showed that the sources for the pictures, diagrams, and photographs of the knife were taken from the Internet, and mercury and accessories for it in the knife were superimposed on top using graphic editors.

The mercury knife of Soviet intelligence officers, which supposedly always hits the target, appears to be an urban legend dating back to at least the 1990s or Soviet times.

Legend

What do our verdicts mean?

Read on the topic:

1. The Legend of the Mercury Knife: Exposed
2. Mercury knives: the secret of Soviet intelligence officers