The inhabitants of large, over-crowded cities, those who work in close, ill-ventilated manufactories, and at the same time have barely a sufficiency of food, and even that of an inferior description, those who habituate themselves to the use of large quantities of spirituous liquors, equally with those who, having ample means at their command, indulge in all kinds of luxury and sensuality, cannot bear the same active treatment as the robust resident in the rural districts, whose avocations are chiefly outdoor, who does not addict himself to the vice of drunkenness, nor indulge in vicious or luxurious habits. The same active treatment necessary to effect the cure of an acute disease in the latter instance, would probably only tend to cause a fatal termination in the persons forming the first class.

It is extraordinary the degree of tolerance which habit establishes, even with respect to the most poisonous substances: thus, Mustapha Shatoor, an opium-eater in Smyrna, took three drachms of crude opium daily.* Suleyman Yeyen, of Constantinople, is said (if it may be credited) to have taken Corrosive Sublimate daily, for thirty years. His usual daily dose was about a drachm; and Mr. Baker, a surgeon on the Bengal establishment, mentions that in Northern India, some of the inhabitants, beginning with one-eighth of a grain of Nux Vomica, gradually increase the dose until twenty grains, or an entire nut, is taken daily. Of course, in these instances, the peculiar article given in ordinary therapeutic doses would be of no avail to individuals habituated to its use. To produce an ordinary effect, under such circumstances, these articles must be given in extraordinary doses; and it should be remarked, that whenever a person accustomed for a long period to a certain amount of stimulus, is suddenly deprived of the article in which he indulges, he is apt to become alarmingly depressed; and in order to sustain the powers of life, it is necessary to continue the accustomed stimulus. Whilst in charge of the jail at Mergui, I was often obliged to give to Chinese prisoners large doses of Opium, not only to prevent their falling sick, but to enable them to perform their daily tasks. When I first assumed medical charge, I attempted, in several instances, to break them of the habit, by gradually decreasing the accustomed quantity; but in almost every case, such an alarming degree of nervous depression supervened, that I was unwillingly obliged to have recourse once more to the use of Opium in the accustomed dose. It is nearly the same with alcoholic drinks; every one is aware of the necessity of continued stimulus, in reduced quantities, in the treatment of Delirium Tremens. It is always a matter of importance, therefore, to ascertain, as far as possible, the previous habits of a patient, in order to enable the practitioner properly to regulate the treatment of the case. (See also some most judicious remarks of Dr. Prout, on the habitual use of mercurial purgatives, Art. Hydrargyrum.)

* Philosophical Transactions, vol. xix. p. 289.

Thornton's Present State of Turkey, Iond., 1807, p. 295.

Bengal Dispensatory, p. 439.