Gustur, here is the current thinking, that differs greatly from Fahrenheit's work.

Basically, the specific heat of a liquid fuel is how close it is already to its boiling point at a given temperature.  It is somewhat counter-intuitive in that the colder a fuel feels when you touch it, the higher its specific heat.  That all depends on pressure.  The greater the pressure, the greater the temperature, though total heat remains constant.  Hence, we have refrigeration. 

Here is the link:

http://en.wikipedia.org/wiki/specific-heat