The Universal Solvent

The Universal Solvent is a 1995 Donald Duck story by Don Rosa.

Plot
Gyro Gearloose has invented a "universal solvent", a thick, black liquid capable of instantly dissolving anything except diamonds, with it then transforming the dissolved matter into a super-dense dust. Gyro then gives the Universal Sovent (referred to as "Omnisolve") kept in a diamond jar and an Omnisolve beach umbrella. Scrooge McDuck buys the solvent from him, intending on using it in mining, in order to gain the super pure diamonds located in the outer core of the Earth. However, in his enthusiasm, Scrooge carelessly pours the solvent directly onto the ground, where it eats a solid shaft all the way down to the centre of the Earth (due to the Omnisolve creating a super-strong and dense lining on the sides of the shaft wall.)

After |Huey, Dewey and Louie explain the potentially catastrophic impact of this act - it would eventually lead to the Earth's destruction by destroying the planet's electromagnetic field and causing the Earth to be bombarded with radioactive solar winds - Scrooge, Donald and the boys go on a quest down the shaft to retrieve the solvent.

They first start slowly going down with an ascent platform created by Gyro. In order to stop the air pressure from crushing them, Gyro creates an airlock over the shaft, making the shaft a vacuum, meaning they cannot eat, much to Donald's comical misery. Their platform is also slightly damaged by a falling pebble (which, due to the vacuum having no air to slow it down, was essentially travelling at the speed of a bullet). Scrooge also finds his diamonds, although he is nearly burned by the massive heat of the diamonds, as they were in the outer core. Later, as Scrooge finds out, they become essentially weightless, due to their weight being their attraction to the Earth's mass, and as they travel deeper, more of the Earth is above them than below them, making them almost weightless. They also find that they have reached a section of the shaft still with air, meaning that they can now eat, much to Donald's glee.

Eventually, they reach the center, and after Scrooge is nearly killed by the Omnisolve, they are able to contain the Universal Solvent. However, the magma from inside the mantle will soon break through the shaft, making them have to use a rocket flight through inner space. Donald has his helmet destroyed by a falling pebble, but still survives, due to air leaking in from cracks. They soon find that the magma is destroying the shaft from the bottom up, and the top of the shaft is collapsing. They are able to escape aided by the Omnisolve umbrella, which saves them from the falling rocks and allows them to create an escape route, but unfortunately, the magma is able to follow them. They eventually find themselves in Terry Fermy, with the Terries and Ferrmies destroying a column, forcing them to use another escape route. They eventually find themselves under the Tulebug River, with the river water solidifying the magma.

They then arrive at the Money Bin (given a lift by Gus Goose), with the top of the shaft about to erupt like a volcano. Gyro is able to stop the eruption with the Omnisolve umbrella, which causes the magma to be reduced into a super-dense dust that kept falling back on itself. Scrooge also gets the super-pure diamonds he wanted in the first place (due to them be carried by the magma, but the Omnisolve umbrella couldn't destroy them). Scrooge's Money Bin is also safe, although it is severely tilted, with Scrooge musing he could still have his workers work there by "wearing some special shoes". In the end, Scrooge deems the solvent as a failed investment. While it did succeed in getting him thousands of flawless diamonds from the bowels of the Earth, he didn't take into account that these diamonds are super-dense, and thus even the smallest ones weigh over 100 kg (200 pounds) each, making them useless as jewellery. He then destroys the Omnisolve notes with the Omnisolve itself, much to Gyro's relief.

This story was inspired by the novel A Journey to the Center of the Earth and was based on a Pertwillaby Papers adventure titled Vortex. It was also likely a partial sequel of the classic Carl Barks story, Land Beneath the Ground!. Don Rosa wrote two sequels to this story, called The Black Knight and The Black Knight Glorps Again.