What I had to do was to build a calorimeter. A calorimeter to measure specific heats. You know the specific heat tells you how much energy you have to put into the material to increase the temperature by 1°C. And that amount of heat tells you where the energy is going, it goes into the vibrations, it goes into the rotation and the translation of the molecule, so the specific heat is an indicator of the energy states of the molecule which they can assume. Of course, it also gives a contribution to the interaction among the molecules, especially to the hydrogen bonding, so when you heat up water you break some of the hydrogen bonds and there is a bond energy involved, and so that shows up in the specific heat. That's why Eucken wanted to have measurements of specific heat, and I had to build a calorimeter, which is a very precise instrument. To give you an impression of that, it's a so-called adiabatic calorimeter, which means that the whole vessel containing the heavy water is surrounded by a mantle, and then there is a differential thermocouple which measures the temperature between the inside and the outside, and you regulate the heat at the mantle such that there is no temperature difference between inside and outside, so heat loss cannot occur. That's the adiabatic calorimeter. And to give you an impression, the thermocouple measures a temperature precise by one thousandth of a degree, and the whole measurement went over about 100°C, so hundred and a thousandth, that gives you the five decimals which we needed for the measurement.
Well, I built such an instrument and started my...
[Q] You mean the glass shop built this sophisticated instrument?
Oh yes, the glass shop and the mechanic machine shop...
[Q] According to your [design]...
The other thing, there'd be the heating which is electric and so on, precise measurements of course, you have to measure very carefully the voltage and the current and so on. But the big question which appeared was, to what temperature can we go? Eucken, of course, wanted to go as high as possible with the temperature, and since the water was melted into the glass vessel, the question is: what pressure does a glass vessel withstand?
