Suspend the reservoir (the tip) of the thermometer in the gas. Do not allow the tip to touch the walls or bottom of the container. If the thermometer bulb touches the container, the temperature of the glass will be measured instead of the temperature of the gas. Readings may be incorrect, particularly if the flask is on a hotplate or in an ice bath.
Note any flow rate or circulation of the gas. If the gas is not circulating, it is possible that the temperature observed is not accurate for the entire sample due to local temperature gradients (hot or cold spots).
