However before this decimalisation WA Poucher originally classified essential oils according to the 88 notes to be found on a piano hence 'top', 'middle' and 'base' notes which helped him remember and personalise the fragrant compounds he worked with. Like musical notes some essential oils like the floral and citrus fragrances have a sharp quick note which quickly falls away while some a relatively long lived and take upto 24 hours to evaporate. Composing a perfume was like composing a tune with lingering base notes, impressive middle notes and sharp short lived top notes.
Oils containing the smallest and therefore the most volatile of molecules are termed 'top' or 'head' notes, those containing more of the heaviest and least volatile molecules are called base notes, those in the middle as 'middle' or 'heart' notes.
Find out more- see Poucher's scale
One of Shirley Price's contributions is to apply this to the emotional effects of the oils. Top notes being more volatile are indicated when the mind needs a lift as in poor concentration or despondancy. Bottom notes being more relaxing come into their own for relieving intense feelings which are difficult to let go like anxieties and stresses. With this in mind when blending oils for a particular individual oils can be selected from each group. "the fact that you love the smell is healing in itself" ref Aromatherapy Workbook p182A good example of this is Sandalwood which is burned by middle eastern brides on honeymoon to relax their husbands.
WA Poucher is perhaps better known for his love of British mountain photography. Find out more.