first smelt it, immediately recurred. Everybody experiences such associations in great number, and in examinations a little trouble will bring them up, especially when the question deals with remote events, and a witness tells about some “accidental” idea of his. If the accident is considered to be an association and studied in the light of a memory of odor, one may often succeed in finding the right clew and making progress. But accurate as the sense of smell is, it receives as a rule little consideration, and when some question concerning smell is put the answer is generally negative. Yet in no case may a matter be so easily determined as in this one; one may without making even the slightest suggestion, succeed in getting the witness to confess that he had smelled something. Incidentally, one may succeed in awakening such impressions as have not quite crossed the threshold of consciousness, or have been subdued and diverted. Suppose, e.g., that a witness has smelled fire, but inasmuch as he was otherwise engaged was not fully conscious of it or did not quite notice it, or explained it to himself as some kitchen odor or the odor of a bad cigar. Such perceptions are later forgotten, but with proper questioning are faithfully and completely brought to memory. Obviously much depends on whether anybody likes certain delicate odors or not. As a rule it may be held that a delicate sense of smell is frequently associated with nervousness. Again, people with broad nostrils and well developed foreheads, who keep their mouths closed most of the time, have certainly a delicate sense of smell. People of lymphatic nature, with veiled unclear voices, do not have a keen sense of smell, and still duller is that of snufflers and habitual smokers. Up to a certain degree, practice may do much, but too much of it dulls the sense of smell. Butchers, tobacconists, perfumers, not only fail to perceive the odors which dominate their shops; their sense of smell has been dulled, anyway. On the other hand, those who have to make delicate distinctions by means of their sense, like apothecaries, tea dealers, brewers, wine tasters, etc. achieve great skill. I remember that one time when I had in court to deal almost exclusively with gypsies, I could immediately smell whether any gypsies had been brought there during the night. Very nervous persons develop a delicateness and acuteness of smell which other persons do not even imagine. Now we have no real knowledge of how odors arise. That they are not the results of the radiation of very tiny parts is shown by the fact that certain bodies smell though they are known not to give off particles. Zinc, for example, and such things as copper, sulphur, and iron, have individual odors; the latter, particularly when it is kept polished by a great deal of friction,--e.g., in the cases of chains, key-rings kept in the pocket.