Steam digester Torricelli and further developed by German scientist Otto von Guericke with his Magdeburg hemispheres. Guerike's demonstration was documented by Gaspar Schott, in a book that was read by Robert Boyle. Boyle and his assistant Robert Hooke improved Guericke's air pump design and built their own. From this, through various experiments, they formulated what is called Boyle's law, which states that the volume of a body of an ideal gas is inversely proportional to its pressure. Soon the ideal gas law was formulated. Based on these concepts in 1679 a Boyle's associate, named Denis Papin, built a "bone digester", which is
Combined gas law pressure as long as it is at a constant volume. The inter-dependence of these variables is shown in the combined gas law, which clearly states that: This can be stated mathematically as: where: For comparing the same substance under two different sets of conditions, the law can be written as: The addition of Avogadro's law to the combined gas law yields the ideal gas law. Boyle's Law states that the pressure-volume product is constant: Charles's Law shows that the volume is proportional to the absolute temperature: Gay-Lussac's Law says that the pressure is proportional to the absolute temperature: The algebraic