Why must a sample reach boiling water temperature in specific heat capacity experiments?

[theintarnets]

Recently, I did a physics lab experiment to find the specific heat capacity of an unknown sample material. The lab instructions kept insisting that the sample had to be kept in boiling water for at least 10 minutes. My question is why? Could I have found the specific heat capacity if the sample were just placed in hot--but not boiling--water for 10 minutes?

 

[mfb]

Boiling water has ~100°C everywhere, and if you wait long enough your whole sample has this temperature. With hot water, it might be more difficult to find the temperature.

 

[theintarnets]

But we used a thermometer and data collection program to obtain the temperature of the water anyway, so does it still matter then?

 

[Integral]

The long soak in boiling water is to ensure that the sample is at 100C clear to the center, it may not take 10min but then how long does it take? Do you know?