Robert Boyle was born on 25 January 1627 in Ireland. He is considered as " founder of modern chemistry" by many people. We all know him for the Boyle's Law. What he did was to take a J-shaped glass tube and to trap some air in it over mercury. He found that when he doubled the weight of the mercury, the volume of the trapped air was half. Then he did many other experiments by changing the ratios. He also realized that it wasn't possible to compress gas, so he deduced that air must consist of particles.
His masterpiece is The Sceptical Chymist.
He was also very religious and published a lot of religious books.
more on Boyle : http://plato.stanford.edu/entries/boyle/