Oil burners are perfect to spread aroma around your home. 
 
To use, put water in the cup and top with a few drops of your favorite essential oil. Light a tea light to warm the water and diffuse the aroma. 
 
After use, allow to cool then gently wipe the oil well with a clean, damp cloth or mild detergent. Dry thoroughly. Brass will oxidise with age, effecting a natural patina. Allow its evolution, or restore the original finish with a brass polishing solution.
 
Please be very careful with these - never leave a tealight unattended.