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
Molar volume an ideal gas: Hence, for a given temperature and pressure, the molar volume is the same for all ideal gases and is known to the same precision as the gas constant: "R" = 0.082 057 338(47) L atm K mol, that is a relative standard uncertainty of 5.7×10, according to the 2014 CODATA recommended value. The molar volume of an ideal gas at 100 kPa (1 bar) is The molar volume of an ideal gas at 1 atmosphere of pressure is For crystalline solids, the molar volume can be measured by X-ray crystallography. The unit cell volume ("V") may be