As to the analogy to be found between the alleged action of the infinitely attenuated doses, and the effects of some odorous substances which possess the extraordinary power of diffusing their imponderable emanations through a very wide space, however it may be abused in argument, and rapidly as it evaporates on examination, it is not like that just mentioned, wholly without meaning.  The fact of the vast diffusion of some odors, as that of musk or the rose, for instance, has long been cited as the most remarkable illustration of the divisibility of matter, and the nicety of the senses.  And if this were compared with the effects of a very minute dose of morphia on the whole system, or the sudden and fatal impression of a single drop of prussic acid, or, with what comes still nearer, the poisonous influence of an atmosphere impregnated with invisible malaria, we should find in each of these examples an evidence of the degree to which nature, in some few instances, concentrates powerful qualities in minute or subtile forms of matter.  But if a man comes to me with a pestle and mortar in his hand, and tells me that he will take a little speck of some substance which nobody ever thought to have any smell at all, as, for instance, a grain of chalk or of charcoal, and that he will, after an hour or two of rubbing and scraping, develop in a portion of it an odor which, if the whole grain were used, would be capable of pervading an apartment, a house, a village, a province, an empire, nay, the entire atmosphere of this broad planet upon which we tread; and that from each of fifty or sixty substances he can in this way develop a distinct and hitherto unknown odor:  and if he tries to show that all this is rendered quite reasonable by the analogy of musk and roses, I shall certainly be justified in considering him incapable of reasoning, and beyond the reach of my argument.  What if, instead of this, he professes to develop new and wonderful medicinal powers from the same speck of chalk or charcoal, in such proportions as would impregnate every pond, lake, river, sea, and ocean of our globe, and appeals to the same analogy in favor of the probability of his assertion.

All this may be true, notwithstanding these considerations.  But so extraordinary would be the fact, that a single atom of substances which a child might swallow without harm by the teaspoonful could, by an easy mechanical process, be made to develop such inconceivable powers, that nothing but the strictest agreement of the most cautious experimenters, secured by every guaranty that they were honest and faithful, appealing to repeated experiments in public, with every precaution to guard against error, and with the most plain and peremptory results, should induce us to lend any credence to such pretensions.