Robert Boyle How exactly did Robert Boyle arrive at the law relating pressure and volume of a gas? Check it yourself and see. This site provides Boyle's original experimental set up and data. Diffusion of Gases The rate of diffusion of a gas is inversely proportional to the square root of its molar mass. To make sure you understand what this means and to read about gas diffusion applications, visit the site R.H. Logan has created for his chemistry students at North Lake College in Dallas, Texas.