Self-contained breathing apparatus pressure changes with ambient temperature. As temperature decreases, the pressure inside the cylinder decreases. The relationship between the temperature and the pressure of a gas is defined by the formula "PV" = "nRT". (See Universal gas constant.) What is particularly important to understand from the formula is that the temperature is in kelvins, not degrees Fahrenheit. Consider the freezing point of water at 32 °F (0 °C, 273.15 K) and compare it to 96 °F (35.6 °C or 308.71 K; normal human body temperature is 37 °C). While 96 is arithmetically three times 32, the difference in temperature from a
Centigrade 232 another Centigrade 232 poem ("Ode To A Crystal Set") appear on the CD's opening track "Second Degree Soul Sparks". In October 2007, Voiceprint Records re-issued "Centigrade 232" in a package containing both a reprint of the 1977 book and a CD of the 1986 recitations. Voiceprint Records label head Rob Ayling passed a copy of the cassette tape of Calvert's recitations to Dave Brock and asked him to set some of the titles to music. The music was played by the then current line-up of Hawkwind, but some titles were lost at the mixing stage delaying the release until August