 In 1761, Joseph Black discovered that heating a body doesn’t always raise its temperature. In particular, he noticed that heating ice at 0°C converts it to liquid at the same temperature. Similarly, there is a latent heat of vaporization which must be supplied for the conversion of liquid water into steam at the boiling point without raising the temperature. It was some time before the modern interpretation of Black’s ground-breaking discovery was fully developed. He had shown that heat must be distinguished from the state of warmth of a body and even from the changes in that state. But it wasn’t until the development of thermodynamics that heating was distinguished as a process from the property or quality of being warm without reference to a transferred substance.