The three chief alkaloid constituents of opium are morphine, narcotine, thebaine, of which the first is the principle peculiar to the poppy, and gives it its stupefying power. The second, narcotine, which in spite of its name has nothing narcotic in it, is a febrifuge and stimulant like quinine; the third, thebaine, affects the nervous system, and is credited by the Chinese with having certain aphrodisiac qualities. Needless to say, however, it is not as a medicine that the opponents of opium find fault with its use, but as a luxury that ensnares the appetite, and enfeebles the mind and body of its hapless votaries. We shall have occasion to show that in the case of the Chinese at least there is an intimate relation between its use as a luxury and as a medicine. There are three ways in which opium may be consumed: it may be eaten in the shape of pills, drunk as a solution, or smoked as a highly-concentrated extract. And it may here be remarked at once that opium smoked is a quite different thing from opium swallowed, so that arguments proving the pernicious effects of the latter will not of necessity apply to the former at all; while, on the other hand, arguments tending to show the harmlessness of opium eaten or drunk will _a fortiori_ prove the innocuousness of opium smoked. The opponents of opium have disregarded this important distinction. Hence much of their evidence against opium-smoking is wholly irrelevant. Sir George Birdwood,[36] relying on the authority of Sir Robert Christison, and on the knowledge derived from personal experience, asserts that opium-smoking _must_ be absolutely harmless, as the active principles contained in opium are not volatizable. Theoretically this may be sound enough, but its practical effect upon Asiatics at least can scarcely be reconciled with this supposition. However this may be, opium-smoking is probably not much worse than tobacco-smoking, and far less injurious than dram-drinking; while opium smoked, whatever be its effect upon the system, certainly has not one-tenth part the potency of opium swallowed. And it is obvious that this must be so, for, when swallowed, all the various constituents of opium are admitted into, and retained by, the stomach; whereas, when smoked, only the narcotizing agent, which is volatizable, finds its way into the system, and that merely momentarily. No doubt opium smoked produces its effect _sooner_ than opium swallowed, for it is brought at once into contact with the blood in the lungs, and thus quickly permeates the whole system. The Chinese are generally credited with being the first people to smoke the drug, and the practice is almost confined to them now.