Henry Cavedish, the eldest son of Lord Cavendish, was an English chemist and physicist who was born on October 10, 1731, died on February 24, 1810, and had an amazing life in between. He was the first to recognize hydrogen gas as a distinct substance. He also described the composition of water and made the first accurate measurement of the density of the Earth. These things may seem irrelevant to us and looked at as common knowledge with the advancements in our lifetime, but these were serious and amazing discoveries in Candish's time.
Cavendish approached most of his investigations through quantitative measurements. In order to establish that hydrogen gas was a substance entirely different from ordinary air, he calculated their densities as well as the densities of several other gases. He found that common air, as well as air brought by a balloon from the upper atmosphere, is made up of nitrogen in a 4 to 1 ratio by volume.
He also showed that water is composed of oxygen and hydrogen. He measured heats of fusion and evaporation as well as specific heats and those of the mixing of solutions in water. Cavendish's measurements of the freezing points of various solutions showed the existence of compositions that yield maximum and minimum freezing points.
As for Cavendish's schooling accomplishments, there isn't much to be said. Cavendish did attend Cambridge University from 1749 to 1753, but left without a degree.
After touring Europe with his brother, he lived frugally in London, even after an inheritance made him one of the wealthiest men in England. He immersed himself in scientific studies, but did not bother to publish a number of his important discoveries. Exceedingly shy and retiring, Cavendish was sociable only with his scientific friends.
Cavendish compared the electrical conductivities of equivalent solutions of electrolytes and expressed a version of Ohm's law. His last major work was the first measurement of Sir Isaac Newton's gravitational constant, together with the mass and density of the Earth. The accuracy of this experiment was not improved on for nearly a century.
Cavendish was nearly obsessed with making scientific observations, even, as legend has it, until the very moments of his death. It was reported by Lord Brougham that on his deathbed Cavendish wanted to be left alone so he could accurately observe and record the progress of his disease throughout his body.
Cavendish truly is a first class scientist and should be considered with some of the great physicists of all time.