many new odours—smells, that is to say, which have no fellow in the world of Nature—and he emphasises the fact that the nose is nevertheless capable of appreciating such novel sensations.
In this connection we may mention that the art of modern perfumery can imitate closely many of the natural perfumes, and more particularly the natural flavours, by mixing together essences, or components, which in no way resemble the final product.
Thus the flavour of peaches can be compounded artificially of aldehyde, acetate, formate, butyrate, valerianate, œnanthylate, and sebate of ethyl, and salicylate of methyl, with glycerine, glycerine being added to the fruit essences, as it is to wines, in order to restrain the evaporation of the volatile bodies. (The fruit essences are used only in the making of flavours. They cannot be employed as perfumes, as they are too irritating to the nose.)
The union of components to form a product different from any one of them is found also in vision, When the colours of the spectrum, for example, are commingled, the resultant white light is devoid of any colour.
Thus the potential responsiveness of the olfactory organ seems to be practically inexhaustible. So far, at all events, it has not yet reached the limits of its capacity.
