Patchouli 30 Sandal wood 32 Geranium 33 Oil of cloves 33·5 Otto of roses 36·5 Bergamot 44 Lavender 60 Lemon 67 Orange 67 Thyme 68 Rosemary 74 Oil of laurel 80 Chamomile flowers 87 Spikenard 355 Anise seed 372 The absorption of thyme and lavender shows how much aroma is lost when plants are dried. So great is the absorption of heat, that the perfume of a flower-bed may be more efficacious than the entire oxygen and nitrogen of the atmosphere above it. The enormous absorption and consequently radiating power of the perfumes of plants and flowers is a proof that their constituent parts are molecules and not simple atoms, incredible as it may seem. The absolute weight of the substances producing these wonderful effects is unknown, but there must be great differences: some perfumes are carried to vast distances, others are less volatile, and that of mignonette was remarked by Dr. Wollaston to be absolutely so heavy that it was quite as powerful below a balcony containing a box of that plant, as in the balcony itself. The perfumes during the experiments adhered to all parts of the apparatus so pertinaciously, that after a continued stream of dry air had been pumped through the tube till the exhaustion seemed to be complete and the needle stood at zero, after a few minutes’ repose, the residue of the perfume came out so powerfully from the crannies of the apparatus as almost to restore the original deflection. ‘The quantities of those residues must be left to the imagination to conceive. If they were multiplied by billions they probably would not obtain the density of the air.’ The absorptive power of the odour of musk was 72 or 74 times that of the air that conveyed it into the experimental tube; the quantity that produced it was quite inappreciable, yet the perfume was so persistent that the pieces of the apparatus through which it had passed had to be boiled in a solution of soda before they were fit for other experiments.