历史上，“比重”有多种含义：当其单位为 kg/m3时，应称为体积质量；当其单位为 1，即表示在相同条件下，某一物质的体积质量与另一参考物质的体积质量之比时，应称为相对体积质量 定义为热容除以质量，单位为 J/(kg· K)定义为定压热容除以质量，单位为 J/(kg· K)。称为定压 Historically, “weight” has a variety of meanings: When its unit is kg / m3, it should be referred to as volumetric mass; when its unit is 1, it means that under the same conditions, the volumetric mass of one substance and that of another reference substance The mass-to-volume ratio shall be defined as the mass of heat divided by the mass in J / (kg · K) defined as the constant pressure heat capacity divided by the mass in J / (kg · K). Called constant pressure