Calorimeters for making measurements at pressures above 1000 bars

A calorimeter suitable for measuring the latent energy of a sample at a pressure of at least 1,000 bars, especially the latent energy of change of state, comprising:

• a thick walled test chamber able to withstand very high pressure,
• means for changing the state of a sample in said test chamber essentially comprising means for pressurizing said test chamber including pressure measuring means,
• a connecting means having a small flow section disposed between said test chamber and said pressurizing means,
• a reference body thermally equivalent to said test chamber,
• respective thermally insulating jackets surrounding said test chamber and said pressurizing means,
• an isothermal enclosure in which said test chamber and said reference body are symetrically arranged,
• means for holding said isothermal enclosure at a set temperature,
• a differential gas thermometer comprising respective bulbs in thermal contact with said reference body and thick walls of said chamber externally to this latter, and
• a two inputs differential pressure measuring unit, each input respectively connected to said thermometer bulbs by capillary connections, where the sensitivity of said differential pressure unit is such that temperature differences lesser than 10.sup..sup.-5 .degree. C, may be detected within the range - 30.degree. to + 150.degree. C.