Piesse's gamut of odours

The 1855 edition states the idea in a few sentences. Odours act on the olfactory nerve in definite degrees, like sounds; there is an octave of odours in which certain odours coincide like the keys of an instrument. He gives two groups: almond, heliotrope, vanilla and orange blossom give one impression; citron, lemon, orange peel and verbena make a higher octave. Rose and rose geranium are a half note; petitgrain and neroli a black key before orange flower.

Right after, in a recipe for sweet pea, Piesse explains why he fixes it with vanilla rather than musk: vanilla strikes the same key as orange blossom, so as the ingredients evaporate the scent on the handkerchief does not turn into a different idea. Blends not built this way, he says, soon turn sickly. This is a compounder's argument, not a physicist's.

The third London edition of 1862 expands this into a chapter. Piesse cites contemporary theories linking colours to musical notes, then prints the gamut on two clefs: the treble from F (civet) down to D (violet), the bass from C (rose) down to C (patchouly). The almond group of 1855 remains, but orange flower is replaced by clematis. He writes that he knows no odour in a chemical laboratory to which he could not assign a key.

The easiest way in is to group odours by note name across octaves. The D row shows that the gamut grew out of the 1855 paragraph: vanilla, clematis, heliotrope and almond all sit on D, the very group he called one impression. Piesse held that odours which chord together give a harmonious bouquet; he printed a few bouquet recipes written as chords, and called citronella the complementary of vanilla.

The order from low to high does not follow volatility consistently. Patchouly, vanilla and benzoin sit at the bottom of the bass clef, in line with a sense of weight. Yet civet, a long-lasting animal material, is the highest note of the treble, and ambergris also sits in the treble, beside cedrat and bergamot.

Odour names follow the 1862 printing. In Piesse's own book, Portugal is orange peel essence and Castor is the beaver secretion (castoreum). Stocks and Pinks are stock (Matthiola) and garden pinks.

Sound has a measurable physical quantity, frequency, and an octave is a doubling of it. That is why a C in different octaves really is related. Odour has no matching quantity. An odour's place on Piesse's gamut rests only on his own perception, and he gives no way for anyone else to check it.

In 1916, when building his smell prism, Hans Henning stated plainly that odour space has no repetition like the octave, no pairs that cancel like complementary colours, and no contrast. Twentieth century biology went further: in 1991 Linda Buck and Richard Axel described a large family of receptor genes; humans have about 400 working odorant receptors, and each odour is coded by a combination of them. There is no single axis on which odours run from low to high.

The gamut is no longer used, but the way of speaking is. The 1862 chapter already has the full set of words: key, note, chord, harmony, discord, treble clef, bass clef. Perfumers today speak of top, heart and base notes, and call a group of materials blended into a new impression an accord. Jean Carles, in articles of the early 1960s, built a whole method of composition around the word accord.

Piesse's value lies somewhere other than what he claimed. He did not find a physical law of odour. He offered a shared way of talking for people who work with odour, in a trade that until then passed its knowledge on mostly by word of mouth.

Publication year: the main history page gives 1857 after the Gutenberg copy; the first edition is London 1855.