Only sugar, Sir !

It was a clear winter morning when Mr.X left hotel.He found 

a nearby stall  and ordered for a cup of tea.Soon he found the

owner, strangely occupied in an unusual task. Every now and

then he would remove the cap of a container,inspect for a while

and put it back.

Unable to control his curiosity Mr.X asked, 

"Is there anything special there?"

"Only sugar,Sir-doctor's advice to check it regularly !"