It is because in that time science was not established. This is, the experimentation to test hypotheses, which is a fundamental part of the scientific method, was not applied.
Atoms can not be seen, then they could only reflect or philosophize on this matter. This method is not able to give good answers to so complicated scientific matters.
Answer:

Explanation:
Hello,
In this case, by knowing that the heat due to a change of temperature is given by:

Whereas Q accounts for the heat, m for the mass, Cp the heat capacity and ΔT for the change in temperature. In such a way the required heat results:

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