Medical German surgeon, whose physical studies enabled him to enunciate the first law of thermodynamics. He/She also calculated the difference between the specific heat of a perfect gas pressure and constant volume, and the mechanical equivalent of heat.
He was born on November 25, 1814 in Heilbronn, and died on March 20, 1878, in the same city. He/She studied medicine in Tübingen and completed their knowledge in Munich and Paris. In 1840, he/she embarked for a trip to the West Indies, where he/she traveled as a naval physician, and spent a few months on the island of Java. In the course of this trip he/she studied the variations produced in the human body and, in particular, in the blood, due to the influence of warm climates. Java noted, to operate a native, the venous blood of this had an intense red color, almost as much as the blood, in contrast to what was observed in venous blood of individuals from other parts of the planet; and as you know, this blood is coming into the lungs to breath. Mayer explained this phenomenon with the affirmation that in the tropics, with a warm climate, high consumption of oxygen is not required to maintain the temperature of the body, and therefore requires a degree of oxidation under food. Over the years, the idea became the first statement given by Julius, of the principle of the conservation of energy or the first law of thermodynamics.
On the other hand, taking into account the equivalence between the heat and the energy of movement, in 1842, Mayer suggested a general equivalence between all forms of energy conservation. It postulated that in nature there are forms of energy that are not necessarily associated with the movement, case of the kinetic energy, or with the lifting and lowering of a body, which would be the potential energy, and therefore considered the existence of other forms of energy. It established a clear equivalence between heat and mechanical energy (kinetic or potential), taking into account that the heat can be generated by friction and therefore had to be a form of movement. Three years later, in 1845, Mayer managed to determine the "equivalent mechanical heat", i.e., the amount of heat for a given amount of kinetic or potential energy (1 calorie = 4,184 joules). Also is credited with the calculation of the difference between the specific heat of a perfect gas at constant pressure and volume (R = 1.98 cal/mol c).
However, he/she was ridiculed and attacked by the physicists, which taking advantage of the lack of clarity of the writings of Julius, did not accept these discoveries, and less if they came from a doctor, by what his work went unnoticed by the scientific community and not received any credit for the next 20 years. In addition, when Joule basically stated the same principle of conservation of energy, both came into a controversy by priority, that led to the internment of Julius in a toilet, which later came.
His scientific thoughts, that not both experiments, were reflected in his essay comments on the powers of inorganic nature (1851). He/She also wrote the organic movement in its dealings with the metabolism (1845).