CO₂ is not a simple, immediately graspable substance like water, salt, or mercury. It has to be conceptually and instrumentally constructed since, as an air-like GE 241 substance, CO₂ is almost invisible, almost odorless and quickly diffuses into the surrounding air; and it is only through special instrumental apparatus (such as a pneumatic trough) or in hermetically sealed locations that it can be(come) sufficiently concentrated for it to be recognizable as a unique individual substance. This constructive work was carried out between the seventeenth and early nineteenth centuries. The older belief in the special status of 'spirits' was displaced by the concept of gas - but only in laboratories. In public communication, 'gases' continue to be emotionally charged substances that are in no way normal. Further investigation of the history of CO₂ shows that the substance has been increasingly politicized and moralized since around the 1980s in the context of the climate change debate. Chemical CO₂ is being reconstrued as a 'pollutant' that threatens the earth and future generations.