Answer:
Josef Loschmidt was an Austrian physicist who derived a formula to calculate the number of molecules in a gas, and in 1865 calculated the size of a gas molecule to be approximately 10^-10 meters in diameter. Amedeo Avogadro proposed the hypothesis that equal volumes of gases contain the same number of molecules, and in 1811 suggested that the number of particles in one mole of a substance is proportional to the volume of gas under standard conditions. Avogadro's number was named by Jean Baptiste Perrin, but the name can be misleading. Therefore, the number should be called the "Loschmidt-Avogadro number" or "the Avogadro-Loschmidt constant" to recognize both scientists' contributions to the concept.