I can't rmb whether emf measured by the thermocouple is directly
proportional to the difference of temperature between the cold
junction and the hot junction.
If it is,
E = ad
where E is the emf, a is a constant and d is the difference in
temperature between the cold junction and hot junction.
When E = 12 mV, d = 100 - 0 = 100,
12 = a(100)
a = 0.12
E = 0.12 d
When E = 4.20,
4.20 = 0.12 d
d = 35
Therefore, temperature of the liquid = d + 0
= 35
