In liquid perfume, the liquid is a mixture of alcohol, water and molecules that evaporates at room temperature. A smell is basically a molecules that is light enough to float in the air, although not every molecule that is light enough to float in the air, has a smell- carbon monoxide. What creates the fragrance is that cells in your nose recognize the evaporating molecules and send electrical messages to your brain, which creates a perception. In fact, most perfumes are engineering to have a three- part smell, which unfolds after you apply it to your skin. You smell top notes within the first 15 minutes of applying. These chemicals first evaporate off your skin. Designers often put weird, unpleasant or spicy smell in this phase so that they interest you but do not hang around long enough to offend. Heart notes appear after 3 to 4 hours. The chemicals creating these smells evaporate more slowly from your skin. They are probably what you remember about the perfume, if it is a floral perfume, flowery smells go here. Base notes stick stubbornly to your skin. You smell them within 5 to 8 hours of application. The sense of smell, or olfaction, varies dramatically from one person to the next. What we can and cannot smell is often genetic, scientist are finding. Some people are simply born with the ability to smell more substances, and with greater sensitivity, than others. Perfumers are some of those people. A good nose is critical to the work, as curiosity. Temperature and humidity affect odor because they increase molecular volatility. This is why trash smells stronger in the heat and cars smell musty after rain. A smell can bring on a flood of memories, influence people’s moods and even affect work performance.
