Graham's law has come to denote an important class of finely divided materials. Around the time Graham did his work, the concept of molecular weight was being established largely through the measurements of gases. Daniel Bernoulli suggested in 1738 in his book Hydrodynamica that heat increases in proportion to the velocity, and thus kinetic energy, of gas particles. Italian physicist Amedeo Avogadro also suggested in 1811 that equal volumes of different gases contain equal numbers of molecules. Thus, the relative molecular weights of two gases are equal to the ratio of weights of equal volumes of the gases. Avogadro's insight together with
HAZMAT Class 2 Gases HAZMAT Class 2 Gases The HAZMAT Class 2 in United States law includes all gases which are compressed and stored for transportation. Class 2 has three divisions: Flammable (also called "combustible"), Non-Flammable/Non-Poisonous, and Poisonous. This classification is based on the United Nations' Recommendations on the Transport of Dangerous Goods - Model Regulations. In Canada, the "Transportation of Dangerous Goods Regulations", or TDGR, are also based on the UN Model Regulations and contain the same three divisions. A gas is a substance which Division 2.2: Non-Flammable, Non-Toxic Gas This division includes compressed gas, liquefied gas, pressurized cryogenic gas, compressed gas in