82 THE LEMON 
Let the spray fly through a match flame. What 
happens ? 
What do you conclude that the lemon spray is? 
20. Our problem is now solved. The lemon spray is 
oul. , 
If, now, you will look again at the skin, you will 
see the spots that you found in § 9. These 
spots are little bags or sacs and contain the oil. 
When the skin is pinched, the sacs are pinched 
and the oil flies out. 
21. We can therefore put the following table on the 
blackboard : — 
Oil Lemon spray 
Marks paper Marks paper 
Floats on water Floats on water 
Burns Burns 
Lemon spray is oil 
