盖-吕萨克定律（Gay-Lussac's law）：定量、定容的理想气体，其压强与温度成正比_1.。温度每升高（或降低）1℃，其压力会增加（或减少）其在0℃时压力的1/273.15_2.。

1.

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1802年，盖-吕萨克证明任何气体当升高相同温度时，体积会膨胀相同的比例，即任何气体 都具有相同的热膨胀系数，而发现一个与查理定律非常相似的定律。

注：其实查理早就发现压力与温度的关系，只是当时未发表，也未被人注意。直到盖-吕萨克重新提出后，才受到重视。早年都称「查理定律」，但为表彰盖-吕萨克的贡献而称为「查理-盖吕萨克定律」。

The expression Gay-Lussac's law is used for each of the two relationships named after the French chemist Joseph Louis Gay-Lussac and which concern the properties of gases, though it is more usually applied to his law of combining volumes, the first listed here. The first law relates to volumes before and after a chemical reaction while the second concerns the pressure and temperature relationship for a sample of gas often known as Amontons' Law.