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
Gas collecting tube evacuated tube and the liquid-containing tube gives the mass (formula_7) of the sucked-in liquid, that took the place of the extracted amount of gas.) The given mass-density formula_8 of the liquid permits to calculate the displaced volume (formula_9). Thus giving mass formula_10 and volume formula_11 of the extracted amount of gas, consequently accessing its mass density (formula_12) under atmospheric pressure The mass density of a fluid can be measured by using a gas collecting tube, an analytical balance and two other fluids of known mass densities, preferably a gas and a liquid (with mass densities formula_13, formula_8). Overview: First, mass