Safety precautions to be taken in fractional distillation of petroleum

[jadelamlam]

Homework Statement

My textbook states that one of the safety precautions to be taken in the fractional distillation of petroleum(in school laboratory) is using a small flame to heat the rocksil(rocksil is soaked with petroleum),and avoil using stationary flame for heating.
Can anyone explain?

Homework Equations

The Attempt at a Solution

I guess the reason of using a small flame is to avoid the breaking of test tube(test tube is used to hold the rocksil)?But I have no idea on why shouldn't we use a stationary flame for heating.

 

[jadelamlam]

I have attached a diagram.

 

[chemisttree]

You have a flammable distillate and small apparatus. What might happen if you heat too strongly?

 

[jadelamlam]

So it will burn?

 

[chemisttree]

Only if something bad happens. Think 'strong heat vs. gentle heat' in this small apparatus.