In the evening, when the cooking test was concluded (about
7 pm local time), the gas holder was completely emptied. The values
given by the calibration were written down in order to obtain
the daily production by subtracting this value from the one of the
day before. It was assumed that other impurities apart from carbon
dioxide were negligible, thus, the difference in volume of gas produced
before and after scrubbing were used to estimate the methane
content.