Must light the flame goes out, [2] paragraphs fractionation liquid into a round bottom flask, round bottom flask to cool a few minutes. Otherwise, it will easily lead to the burning of the toluene steam encounter the fire source, causing the accident.

[ 2] to the distillate is poured into a round bottom flask fitted, they must first be in light flame goes out, and let cool for several round-bottom flask fitted. Otherwise, it will be easy to cause the toluene vapor ignition sources encountered ignite, causing an accident.

(2) pours into in the round flask each section of fractionation fluid when must first the lamp flame extinguishment, lets the round flask cool several minutes.Otherwise, can easy cause the toluene steam to meet fire hazard burning, creates the accident.

[2] paragraphs distillation liquid poured in the round-bottomed flask must first be light when flame dies, round-bottomed flasks to cool for a few minutes. Otherwise, prone to combustion of toluene vapor encounters the source of fire, caused the accident.