I'm reading Patriotic Treason: John Brown and the Soul of America by Evan Carton and he mentions these swords. He says they were surplus swords purchased by the Browns for use in their raids. There are so many myths around swords that this seemed like it could be one of those. So I put it to you, was filling hollow swords with mercury a common practice by government armories and did the US ever use them, or anyone else for that matter? I had only heard of them mentioned in Sci-Fi/Fantasy before this.
In researching this, it seems almost unanimous that such blades have never been manufactured in enough quantity to be used in warfare if even manufactured at all.
On a similar note, and one that might have caused the original thought of mercury filled blades, there have been blades with ball bearing filled channels cut into them. These seem to generally be swinging/chopping style blades and the ball bearing channels are rather short compared to the blade length so I am not sure they served a lot of purpose.
what benefit would that have?
Did they even have the production technology to make a hollow sword? Especially one of sufficient strength to not break instantly.
The swords they used at Pottawatomie have an odd history. They were manufactured for a secret society in Ohio called the Grand Eagles, who had plans to invade Canada. They were patterned after US Army Cavalry sabres, but were a little shorter. They also had eagles on the hilt.
But those particular swords were never used by the US Army.
IIRC I read a Mexican War veteran recalling the whistling noise that quicksilver made as it traveled up and down the blade. This was before the era of standardized weapons in the army so there were probably all sorts of crazy inventions.