5. Conclusions

The choice of which method to use will depend on a number of factors:

• the temperature range of interest to the experimenter;

• the shape of the product and, for example, the dropping method excludes powders;

• the precision required ;

• the time the experimenter is prepared to devote to the measurements, since, as we have seen, some methods can take one or more days, others several months, or even two or three years.