Newton's Cannon (The Age of Unreason, Book 1)

Come on a journey sideways through time, and lose yourself in a world both deeply familiar and wondrously strange. In 1681, Sir Isaac Newton turns his restless mind to the ancient art of alchemy, and successfully unleashes Philosopher's Mercury, the key to manipulating the four elements. Powerful kings will battle to control it, till London itself is threatened with obliteration by a hellish device - unless a pair of unlikely geniuses can defuse it in time. This is a fantasy woven from the stuff of history, an enthralling quest whose outcome may raise humanity to unparalleled heights ... or bring down the curtain of endless night.