bottom of the hood! Once everything is secure, vent the apparatus to nitrogen and then remove the heating apparatus and let the set-up cool to room temperature 10)Once everything has cooled, record the weight of your tared collection flask(s) and calculate the weight of your product(s).bottom of the hood! Once everything is secure, vent the apparatus to nitrogen and then remove the heating apparatus and let the set-up cool to room temperature 10) Once everything has cooled, record the weight of your tared collection flask(s) and calculate the weight of your product(s). 62