dying and the dead for several weeks, and breathed the same air as the rest of the inhabitants, with the exception of that confined in the apartments of the sick.

Circumstances like these establish the fact more forcibly than a whole volume of arguments, that the disease was not an epidemic, or derived from any general cause existing in the atmosphere, or from any derangement or alteration in the quality or proportion of its constituent principles, but was propagated by contagion alone, otherwise the persons circumstanced as just mentioned could not possibly have escaped more than the rest of the inhabitants but on the contrary, the emigrants from St. Domingo, not accustomed to this climate, would have been the first to experience its effects, and would have suffered much more severely from the impurity of the atmosphere, if that had been the cause of the disease, than the native inhabitants; for it is a fact confirmed by long and extensive experience, and which admits of no exception, that strangers are the greatest and most certain sufferers from exposure to the causes of the indigenous diseases of the climate into which they migrate. But a contagious fever is communicated only from the sick, or articles contaminated by them. No sick persons were admitted into the prison, the Pennsylvania hospital, or the almshouse, during the prevalence of the yellow fever ; and the emigrants from St. Domingo, having arrived at Philadelphia just as the disease began to make its appearance, had formed little or no acquaintance with the inhabitants, and of course had no intercourse with the sick. This, and this alone is the true reason of their escape, and is a very strong and direct proof that the disease was not derived from the causes which have been

assigned by those who contend that it is of domestic origin and not contagious.

If the disease had arisen from the domestic sources already enumerated, or from the joint effect of these and a deranged state of the atmosphere, all that breathed the air of the city, at least, if not all round the world in the same latitude, would have suffered more or less by it, and nearly at the same time, and not in that gradual and successive manner as they have done every time the yellow fever has made its appearance in any of the seaport towns of this country, and as is observed always to be the case with all the diseases that are acknowledged to be contagious.

The symptoms, also, by which the yellow fever is distinguished from the most dangerous cases of the bilious fever that occur in any part of the world, not excepting the indigenous fevers of Batavia, Calcutta, Goree, or Surinam, which are universally acknowledged to originate from the exhalations of putrefying animal and vegetable substances, furnish additional evidence of their being different not only in degree, but in kind, and consequently that they are derived from different sources.

To infer that the yellow fever is only a variety or higher grade of the indigenous intermittent fever of this country, because it generally occurs, progresses, and terminates at the same time of year as the intermittent, is confounding or mistaking coincidents for causes. By this mode of reasoning the plague of the Levant, with all its complicated horrors, is nothing more than a common intermittent, rendered malignant, or increased in power

by the influence of a deranged state of the constitution of the atmosphere upon its cause, or upon the constitution of the patient; for, when it has been imported into the temperate climate of Europe, from Egypt, Syria or Turkey, it has generally commenced, progressed, and terminated in the same seasons as the common intermittent. For proof of this, see Hodge's account of the plague in London, in 1665, and Martin's account of its rise and progress in Moscow, in 1771.

If coincidence of events always depended on identity of cause, the pleurisy and the meazles would depend on the same cause, and though differing in degree, and in the character of their symptoms, they would be the same in kind, and agree in their nature, and would require a similar mode of treatment; for, according to Sydenham's account, they both begin in the month of February in the climate of England, increase during the spring months, and terminate about the summer solstice.

The only circumstance in which the yellow fever and the intermittent or bilious fever do agree, is, in being both destroyed or disarmed of their noxious power by frost. This, however, only proves that the contagious principle, which is the cause of the yellow fever, requires the same portion of caloric to preserve its volatility, and keep it suspended in the atmosphere as the miasmata of marshes, or the exhalations from putrefying substances, and that it requires considerably less caloric to render the contagion of the typhus of temperate climates volatile, and to keep it suspended in the atmosphere. But the contagion of the yellow fever, like that of the typhus or jail fever, requires to be accumulated or concentrated in the atmosphere in confined and unventilated situations, in order to render it

capable of producing any disorder in those exposed to it; and as the poison of arsenic becomes harmless by copious dilution in water, that also becomes harmless by diffusion in the open air. This is the reason why the disease is so rarely communicated from one to another in country situations, where there is a constant circulation of fresh air. They, therefore, who deny the yellow fever to be contagious in any situation, because it is rarely so in the open and free air of the country, might with equal reason deny that the jail or hospital fever, the typhus gravior of systematic writers, to be contagious, because it only operates in confined and unventilated situations, where cleanliness is neglected, with sufficient power to produce any morbid effect; but like the noxious gases, or other volatile poisons, becomes impotent and inactive by diffusion, or by mixture with a certain portion of fresh and untainted air. Those, therefore, who seem to think it so very extraordinary that the yellow fever, if contagious, does not produce the same noxious effects in the country as in the confined and less pure air of a populous city, I refer for a satisfactory explanation to a collection of facts on this subject published in Dr. Barton's Medical and Physical Journal, vol. 2d, part 1st. I shall now conclude with observing, that if the circumstances stated and detailed in the preceding pages are authentic and correct, and I challenge any person to disprove them, every disinterested and unprejudiced enquirer that examines and compares them with the facts and arguments of the advocates of the domestic origin of the disease must be convinced, that the yellow fever has never originated from domestic causes in this climate, but is exclusively of foreign origin.

I remain your friend, &c.

DR. D. HOSACK.

WM. CURRIE:

VII.

Extract of a Letter from Dr. FELIX PASCALIS, of NewYork, to Dr. ALIRE R. DELILE, on the subject of the Poisons of the UPAS TIEUTE of Java, and other Strychnos.

New-York, February 10, 1810.

DEAR SIR,

I lately received your inaugural dissertation on the poisonous effects of the Upas Tieuté of Java, and other Strychnos, which you have presented to, and defended before, the faculty of medicine in Paris. I hasten to tender you my thanks for your attention, and to bear evidence of the excellence of your memoir. The subject was entirely new, and you have connected it with as many interesting physiological questions as your experiments could embrace. The means by which that violent poison rapidly pervades the sources of life; those by which it may be expelled or rendered inert, and in fine, the progress of its influence, which is chiefly active on the spinal marrow; all these different points form a highly interesting. inquiry. I see also, with infinite pleasure, that you illustrate the new doctrine lately introduced by the celebrated Gall and others, that the spinal marrow is a centre of action totally distinct from that of the brain.

While you prove that tetanus and asphyxia are the immediate effect of the upas, I am prompted to inquire whether this latter is the exclusive and necessary consequence of the former; that is, of the stiffness and immobility of the thorax, as you call it, without any other cause?