found reduced upon the lining membrane of the cavities. The action on the sense is very strong, notwithstanding the minuteness of the dose; there is an intensely bad smell, as of decaying cabbage, and the irritation of the membrane causes catarrh.

These facts so far as they go, prove that there is a chemical action at work in smell, and that this action consists in the combination of the oxygen of the air with the odorous substance.

6. We pass now from the physical to the mental phenomena of smell; the sensations, or peculiar states of consciousness, that all those physical antecedents end in giving birth to. Unavoidable allusion has already been made to these mental effects in the description of the smelling substances.

'Linnæus has divided odours into seven principal classes: 1st. aromatic, as the carnation, the laurel, &c.; 2nd. fragrant, as the lily, the crocus, the jasmine, &c.; 3rd. ambrosiac, among which are musk and amber; 4th. alliaceous, which are agreeable to some persons and disagreeable to others, and more or less of the character of garlic, assafoetida, for example, and several other gum-resinous juices; 5th. fetid, as those of the goat, of the rag-wort (orchis hircina), valerian, &c.; 6th. virulent, as those of Indian pink (l'aillet d'Inde), and many plants of the family of the solanea (from solanum, the night-shade); 7th. nauseous, as the gourd, the cucumber, and those of its class.'-LONGET, p. 151.

Of several classifications quoted by the same author, the above seems to me the best, but even that one is by no means free from objections. The three first classes, the aromatic, fragrant, and ambrosiac, do not appear to have very strongly marked differences; nor is the distinction between fetid and nauseous a generic one.

I shall attempt a classification, on the principle of selecting such tastes as seem to have a well-marked character, and to prevail widely among natural objects. In this attempt, it will be convenient to commence, as in Taste, with those smells that owe their peculiarity to the sympathies of other organs, as the stomach, and the lungs.

7. Fresh odours, those that have an action akin to pure air, or coolness in the midst of excessive heat; an action. mainly respiratory, or tending to increase the activity of the lungs, and with that the physical energy of the system. Many of the balmy odours of the field and garden have this effect; eau-de-Cologne and other, but not all, perfumes are included in the same class. We may recognise them by their effect in stimulating and reviving the system, under the oppression and suffocation of a crowded assembly. Such odours are not always fragrant in their character, for we might cite cases of unpleasant effluvia that seem to refresh and stimulate the system. The odour of a tan-yard is perhaps a case in point. The close connexion of the nostrils and the lungs enables this reaction of the one upon the other to take place; a connexion that doubtless extends to the nervous system, although not traceable there. Or the influence of the gases may be on the surface of the lungs rather than in the nose, a thing not at all unlikely in many cases coming under both freshness and the opposite. On this supposition these would be smells falsely so called, and would correspond to the relishes and disgusts described under taste.

8. The opposite of freshness is shown in the close or suffocating odours. The effluvia of crowds, by acting on the lungs, have pre-eminently this damping and discouraging action on the powers of life, whence it is that we seek the open air, and the solitudes of nature, to shake off the depression of rooms and cities. The effluvia of warehouses, stores, and mills, where cotton, wool, cloths, &c., are piled up, and ventilation is defective, are of a like unwholesome description The smell of a pastrycook's kitchen is peculiarly sickening. The action of highly-heated iron stoves seems of the same nature; also the smell of a woollen screen when held too close to the fire. In these last instances, there is believed to be an evolution of the unwholesome and suffocating gas, cyanogen, from the destructive decomposition of the woolly particles floating in the air, or making part of the screen.

9. Although we may not be able to affirm that any class of odours stimulates the stomach by a direct influence, as fresh

odours do the lungs, there can be no doubt about the existence of a class of the opposite kind, the disgusting or nauseous odours. That is to say, there are certain gases, of which sulphuretted hydrogen is an example and a type, that pervert the action of the alimentary canal, as some tastes do. It is doubtful, at least so far as my information goes, on what surface these effluvia operate, whether on the membrane of the nose exclusively, or partly on it and partly on the mucous surface of the tongue, throat, and stomach. But whatever be the seat of action, the fact in question is one sufficiently well marked to make the specific difference of a class.

10. It may be a question whether the foregoing classes are true and proper effects on the organ of smell; no such ambiguity adheres to the odours that we term sweet or fragrant; these therefore I recognise as a general group with many varieties included under it. They represent the pure or proper pleasures of smell; the enjoyment we are able to derive through the olfactory nerves and ganglion. They include the substances that convey along this channel to the mind a perfectly pleasurable stimulus. The sweetness may accompany freshness or it may not. The odour of the violet I take as a pure instance, there being many such among the flowering and fruit-bearing plants. The cases of sweetness enjoyed with some other quality are also extremely numerous.

The feeling that we term sweetness, is one of the most remarkable experiences of the human mind. It is an effect that recurs upon us in many ways and from very different causes. We have seen it already under taste, and we shall find in the other senses, and in the emotions that pass beyond the scope of Sensation, an effect that is considered as falling under the same general term. This is one of our pleasurable feelings, not of the voluminous or massive kind, like exercise, warmth, or digestion, but intense or keen in the first degree. It stimulates a vivid expression and gesture of the kind marking acute pleasure: and the pleasure is one that is closely allied with tender emotion.

In the region of Volition, we remark an absence of the spur of appetite. We class the state among the serene

emotions,-like repose, warmth, the refreshment and satisfaction of a wholesome meal. In other words the pleasure of smell proper, and of taste proper, has a tendency to satisfy the mind, yielding contentment rather than craving. This is to be a pure emotion. In the case of excess, the state is characterised by the terminating sensation of satiety, which as regards sweetness is a state of peculiar and well-marked unpleasantness, the ennui of sense. The feeling is also one that must be craved for as an agreeable recollection and not as a want; and hence to be an object of pursuit, would need to have a considerable persistence in the memory: but this persistence is not alike for all the forms of it, that is for tastes, smells, sounds, sights, beauty, &c. Of smell in general, as of taste, we cannot affirm any very high persistence or endurance in the absence of the original; it being a matter of some difficulty to imagine the odour of a violet or an orange, while there is far less difficulty in imagining a sweet sound. The conclusion of the whole is that a sweet smell and a sweet taste are serenely pleasurable while they last, characteristically painful if carried to satiety, but not much desired in their

absence.

11. The opposite of sweet in odours can only be described by the general name stinks; the expressive word bitter is not usually applied to smell. The term 'mal-odour' has been proposed, and would be a convenient word. If we leave out both the nauseous odours, and certain other forms of the disagreeable to be afterwards described, this class will be limited considerably. Assafoetida may be given as an example of an odour intensely repulsive by its action on the olfactory nerves alone. The cadaverous odour is of the repulsive kind, but it is only one of many forms of disagreeable effluvia arising from animal decay. The aroma of some plants, as those quoted by Linnæus, has an intensely unpleasant action. The disagreeable marsh smell may be experienced in its strongest form by squeezing in the fingers the brown scum of a stagnant pond, and applying them to the nose. The varieties of bad odours are endless.

As sweetness is the proper pleasure of smell, the effect of

a stink is the proper pain of the organ, the influence that breeds the peculiar forms of misery that we are adapted to receive by means of this sense. The emotion may be specified as the nose-pain. Of an intense, rather than a massive character, we are stunned and discomposed, but not necessarily depressed or prostrated by it. We may compare it to a bitter taste, in this respect, and may contrast both with the massive pains of chillness, indigestion, or disgust. The expression also testifies to the acuteness of the sensation, being an intense contortion of the features, chiefly about the nose. A sort of hysteric smile may likewise be provoked, which, like all emotional outbursts, renders the state less unendurable, that is less volitional.

The Volitional stimulus to get rid of the feeling is simply proportioned to the degree of badness, and is no specific criterion of character. As regards Intellect, the action of a bad odour is sometimes such as to leave a very strong impres sion behind, which, however, would be an exception to the usual nature of smells. The peculiar feeling of an ill smell is often appealed to metaphorically to express the feelings caused by human conduct.

12. The name pungent is applicable to a large class of odours, and enters as an ingredient into many more. Ammonia is the type of substances producing this sensation. Nicotine, the snuff odour, is the best known example, a substance having a chemical analogy to ammonia. Many of the acid effluvia have a pungent action. This effect, however, is not an olfactory effect in the proper sense of the word; like astringency and acidity in taste, it would probably act on the sensibility of the nose independently of the power of smell. Snuff-takers are often devoid of smell; they lose the sense of sweet or repulsive in odours properly so called, but are still susceptible of the nicotine pungency. The influence flows through the same channel to the brain, and is of the same nature, as pricking the nose, or pulling out hairs, being conveyed by the nerves of common sensation.

Nevertheless, the excitement of pungency is a characteristic variety of the human consciousness, a species of agreeable