The fact is that Zwaardemaker’s classification is based upon a chemical foundation, that is to say, upon properties which, as we shall see later on, do not necessarily correspond with the odours as we smell them. That, no doubt, explains his inclusion of iodoform among the “fruity” odours.—Iodoform fruity!—Shades of George Saintsbury and his “Cellar Book”! A shorter classification is that of Heyninx, who, aiming at objectivity, bases his arrangement, to some extent at all events, upon the spectrum analysis of odorous molecules in the atmospheric medium, of which more anon. His list is: acrid, rotten, fœtid, burning, spicy, vanillar or ethereal, and garlicky. But here, also, the coupling of vanillar with ethereal odours seems a little inappropriate. We stand, perhaps, on rather firmer ground when we turn to the manufacturer’s classification, founded as it is frankly upon subjective sensation, and therefore devoid of any surprises to the logical faculty. Here is Rimmel’s arrangement: rose, jasmine, orange, tuberose, violet, balsam, spice, clove, camphor, sandal-wood, lemon, lavender, mint, anise, almond, musk, ambergris, fruit (pear). It may be objected, perhaps, that this is a catalogue merely, not a scientific classification. That is quite true. But what is also true is that the others we have quoted are little, if any, better. The fact is that we do not yet possess the knowledge necessary to enable us to arrange odours in classes. The manufacturers, of course, concern themselves with agreeable and attractive odours only. To the great and growing company of the stinks they pay no attention whatever. For that reason their contribution to our knowledge is necessarily but partial and limited. In their own proper domain, however, they can point to several great successes. They recognise, for practical purposes, about eighty primitive scents. Many natural (to say nothing of many unnatural) perfumes can now be prepared artificially, and some so prepared are said to be even more powerful than the natural productions. Artificial musk, for example, is one thousand times stronger than natural musk, Parker tells us. Deite, on the other hand, says that the smell of artificial musk is not equal to that of the natural! Indeed, according to this authority, although synthetic perfumes play an important part in the concocting of scents, there are only a few of them which can be used instead of the natural product. What happens is that the artificial and the natural are generally used in combination. Thus the “mignonette” of the shops is prepared by passing geraniol, an artificial odorivector made from citronella oil, over the natural mignonette flowers, the resulting product being an essence smelling strongly of mignonette, and not at all of geraniol.