When you open a bottle of rose or lavender scent, do you wonder how it came to be there? Let's have a look at how the fragrance of a rose is trapped and bottled!
You might have read an earlier article about what made perfumes smell nice. In this article, we'll have a look into the many steps of chemistry required to make a perfume from the original flowers.
Every flower or leaf has a few chemicals unique to it. For example, lemon leaves contain a chemical called limonene. This is the one that gives them the unique 'lemon' smell. The reason they smell is because they evaporate easily, and when they enter our nose, the nerves can detect them.
Such chemicals are called 'essential oils'. They are oils because when liquid, they don't mix with water. The word essential refers to the fact that they represent the 'essence' of the plant. Lemon wouldn't seem lemony without limonene.
So how do we get them out?
Over hundreds of years, chemists have found ways and means to separate these essential oils from their plants. Scientists like Al-Kindi and ibn Hayyan were among the first to describe methods.
A common method is steam distillation. You can try it with the help of your chemistry teacher. Set up a distillation apparatus. Get some flowers and crush them (you'll need a lot). Put them on a steel net and put the net in the part where the water boils (but the water shouldn't touch the flowers). Now you're ready to start.
As the water boils, the steam will pass through the crushed flowers. The heat makes the essential oils in them evaporate. As the steam and the evaporated oil pass into the condensation chamber, they'll cool back to water and oil. Keep this vessel overnight. The water and oil will separate, giving you a layer of oil on top.
Carefully collect the oil from the upper layer into a fresh bottle. You can add some alcohol to build up the volume. Now you've got a scent ready!
You need several kilograms of flowers to make just a tiny amount of essential oil. That's why essences tend to be very expensive.
Another common way is to grind the flowers or leaves in alcohol (or other organic solvent). This way you get a mixture of essential oils called a tincture. In some scent factories, they use supercritical carbon dioxide to extract the essential oil. This is an environmentally safer way, as you don't have to use harmful organic solvents.