The first law of thermodynamics and energy conservation
The concept of conservation of matter and motion, although early in the middle of the eighteenth Century by the Russian scientist Lomonosov has been put forward, but the heat is a form of thermal motion, the mechanical motion is concept until can convert each other more than 100 years later by the physicists have known phase. Before this, "phlogiston" also occupy dominant. This theory that heat is a kind of to be special, not the quality of the liquid, called "phlogiston". How much depends on the hot and cold objects with "hot house". "Phlogiston" from warmer objects to cooler objects to exist in the nature of heat in Beijing. Can neither be created nor destroyed, that is, "phlogiston" conservation. Hot house said "the heat as a material, that it is a form of the motion of matter, that can convert between other forms of exercise and substances. Although the use of" hot "can explain many hot phenomenon, but after the invention of the steam engine," phlogiston "and cannot explain the relationship between the heat phase mechanical movement, it has become obstacles to scientific development.
The first experiment to refute the "phlogiston theory" is Furong (Coum Rumford, 1753 - 1814) and David (HumphryDa "Y, 1778 - 1829). Aaron Furong found in drill barrel, barrel and iron temperature, produce a lot of heat, as long as continue to drill, heat is not broken, thus he asserted:" heat can be produced by the motion, it is not a matter. "But," phlogiston "advocates have proposed all sorts of untenable argument, attempt to bring Lun Fude findings into the" phlogiston "track, defend their creed.1799 years, David in London Furong inspiration, is a very convincing experiment: he is in the air friction with two blocks of ice, and has the temperature lower than the temperature of ice, the ice into water. Cut dimension experiment, by the ice to water heat may not be from outside into the" phlogiston ", because the temperature lower the surrounding, also may not be discharged because of specific heat change" phlogiston ", because the specific heat of water than the ice. The experiment proved
"Hot in Beijing said" error, unfortunately, Rumford and Dai Jidou did not find the heat and the work
The number of Customs exemption
N42, the German doctor Mayer (J.R.M, y6r, 1614, 1878) published - 'papers, the energy conservation theory, that heat is a form of energy, with each conversion of mechanical energy from the air, and the specific heat at constant pressure and constant volume specific heat difference calculated for the mechanical equivalent of heat. This is not a direct experimental data, his theory has not been admitted to the physics community at that time. The first law of thermodynamics finally lay thanks to the British physicist Joule (J.P.JoMLe, 1818 l 889), before and after he used twenty years time, determination of mechanical equivalent of heat through various means, consistent results were obtained by L. 850 years, the results of his experiment has the scientific community accepted the validity of the law of conservation of energy.
The first law of thermodynamics is the law of conservation of energy, it has a lot of ways of expression,
For example:
Heat is a form of mechanical energy into heat energy, heat energy into mechanical energy or when the energy, their ratio is certain.
Heat can change into the work, work can also be converted into heat, a certain amount of heat loss, will produce a certain amount of work; consumes a certain amount of work, will have a certain amount of heat.
When a system state after a cycle of change, the algebraic equal to the system in the system of heat power algebra and outward, mathematical expression for it

The first law of thermodynamics and a simple form of expression: the first kind is
Can not be made.