NOTE I. (See page 233.)

THERE is scarcely to be found on record a series of facts which so conclusively prove the specific character of the pestilential or yellow fever, or points out the circumstances under which it is propagated or extinguished, as those referred to in the text: e. g. we have seen this disease introduced at the Wallabout on Long Island in the summer of 1804; and the poison diffusing itself in that neighbourhood as far as the impurity of the air extended; while the same disease conveyed, from the Wallabout into the city of NewYork, was instantly extinguished by means of the relative purity of the atmosphere, the effect of the rigid system of police then observed. See American Med. and Phil. Register, vol. 2.

In like manner, in the summer of 1809, (see Statement by Dr. Gillespie, Amer. Med. and Phil. Register, vol. 1.) the yellow fever was introduced and spread in the village of Brooklyn, Long Island; at the same time that the city of New-York, within eight hundred yards' distance, enjoyed the most perfect exemption from it; a fact which at once disproves the dependence of yellow fever upon a general constitution of atmosphere which many physicians believe to be necessary both for the origin and propagation of this form of fever. We are led to the same conclusion by perusal of the report relative to the introduction of the yellow fever into the city of Amboy, New Jersey, in the summer of 1811. See Amer. Med. and Phil. Register, vol. 3.

NOTE K. (See page 234.)

THE following extract of a letter from the Rev. Dr. Samuel S. Smith, the late president of Princeton College, shows that the fact I have stated of an interval taking place between the first and the subsequent cases of fever is of so frequent occurrence, that it even attracts the notice of those who are unconnected with the medical profession.

DEAR SIR,

Princeton, July 24th, 1808.

I have not any doubt but that yellow fever contains a specific contagion, essentially variant from that of small pox, with which it has so often been compared in order to

deny contagion being incident to it. It requires a certain putrid state of the atmosphere as a conductor, in order to impart it and it may inoculate and assimilate any confined portion of atmosphere which has been exposed to the requisite causes of contamination, so that every part of it shall have power to communicate the poison. In the pure atmosphere of the country the poison is commonly so diluted, that it is too weak to excite the fever, except under peculiar circumstances.

In every instance in which yellow fever has been introduced into Philadelphia one circumstance has invariably taken place after the persons who have first taken the disease have either died, or recovered, there has been an interval of health for several days, usually from ten to thirteen or fourteen, before the alarm has been renewed. From this circumstance, I have concluded, that during that space of time the infection secretly works in the blood before it appears in fever. Often there is a second interval of арраrent health, but not of so long continuance. I hope that your view of the subject will carry more conviction with it than we have hitherto perceived; and I hope it will even contribute, among the more sensible part of the profession, who do not think merely by authority, to unite jarring opinions, and to settle common principles.

SAMUEL S. SMITH.

By physicians who have recorded our epidemics such interval has been repeatedly observed. In Dr. Caldwell's Essay on the Yellow Fever of Philadelphia of 1805, it is very circumstantially noticed by that ingenious and able writer.

NOTE L. (See page 236.)

IN the official document of the Board of Health of New-York, published on the 14th of September, 1805, they thus addressed the inhabitants of this city: "The board have formed a decided opinion, that the principal seat of the prevailing disease [the malignant epidemic fever] is that part of the city included between Burling-slip and Oldslip as far west as Pearl-street. Almost all the cases of disease which have occurred, can be distinctly traced to a communication with that part of the city. It is a matter of extreme regret, that the repeated admonitions of the board, to remove from this quarter, have been disregarded by a number of individuals who have remained the self-devoted victims of disease and death. They conceive it their duty again to enjoin it upon their fellow citizens, who have continued there, to remove immediately." Again, and in the same address: "All persons who do not comply forthwith with this advice of the board,

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to remove from the above described part of the city, which is deemed the principal seat of the disease, and which does not contain more than thirty-three acres, will be considered guilty of a wanton exposure of their lives, and will justify the board in resorting to compulsory measures." The epidemic fever which prevailed in Philadelphia in 1793 spread in a similar manner, according to Dr. Rush and others. "For a while," says Dr. Rush, "this fever was confined to the above-mentioned part of the city, but the disorder is spreading, and now appears in other places, so that several are affected in other parts of Waterstreet; some in Second-street; some in Vine-street; some in Carter's-alley; some in other streets; but, in most cases, the contagion can be traced to Water-street." Proofs of the same kind might be taken from the most authentic accounts of the yellow fever as it has prevailed at other seasons, and in other cities and seaports of the United States: proofs wholly irreconcilable with the assertions of those who have declared that the malignant yellow fever arises at "distant and unconnected points;" that "no relation is observed between the source of the supposed contagion and the spreading of the disease to individuals or families;" and who have maintained that there" never was any successful attempt to trace, in regular series, the propagation of it to any number of persons from the first case, or from any single point of infection.' See Rush's Account of the Bilious Remitting Yellow Fever as it appeared in Philadelphia in 1793; Account of the Yellow Fever of New-London in 1798; Hardie on the Malignant Fever of New-York in 1805; Chisholm's Letter to Haygarth; Official Documents published by the Board of Health of New-York; Amer. Med. and Phil. Register, &c. &c.

NOTE M. (See page 237.)

Hints on Purifying the Air of Infected Apartments, by the late Dr. T. Gurnett, Professor in the Royal Institution, &c.

"IF the air contained in a phial be rendered offensive by the putrid animal and vegetable substances, it may almost instantly be made sweet by dropping into the phial a few drops. of oxygenated muriatic acid; or more effectually still, by introducing into it a small quantity of oxygenated muriatic gas.

"This experiment may be easily made; and it will be found that the air will, in this way, be deprived of the most putrid taint possible. Morveau and Berthollet have found, that if oxygenated muriatic gas be disengaged in a dissecting room, the bad smell from the subject will be corrected for a time; and that if the subject be washed with oxygenated

muriatic acid, it will exhale no bad smell for a considerable time. These curious, but well-ascertained facts, naturally led us to inquire into the action of the oxygenated muriatic acid, in correcting the putrid effluvia.

"It is now well known, that almost all the putrid smells disengaged by putrefying substances, are owing to the extrication of inflammable air, or hydrogen gas, loaded with some or all of the three following substances, sulphur, phosphorus, or ammonia; and these substances do not give out any very disagreeable smell, except when dissolved in hydrogen gas; but in that state we know the smell to be very unpleasant.

"Sulphurated hydrogen gas, or hepatic air, smells very disagreeably; but the hydrogen gas in which phosphorus has been dissolved, often smells most intolerably, resembling the refuse of blubber. The superabundant oxygen of the muriatic acid unites with the hydrogen, and forms water; and the sulphur and phosphorus, being no longer in a state of solution, become concrete, and the bad smell disappears.

"Though it is not yet proved, it seems very likely, from the experiments of Mr. Wall, and others, that the effluvia from the human body communicating infection, is hydrogen gas, charged with some animal substances.

"Is it not natural, from analogy, to conclude, that if these were deprived of their solubility in hydrogen gas, they would become innocent? and may we not reasonably suppose, that the oxygenated muriatic gas will deprive them, as well as other putrid effluvia, of their solubility?

"It certainly, I think, deserves a trial, which may be made at a very small expense, in the following manner:

"Take an ounce of the black oxyd of manganese in powder, and mix with it a quarter of a pound of common salt; put this mixture into an earthen vessel, and place it upon a chafing dish of coals in the room where the person labours under an infectious complaint; then pour upon it two ounces of sulphuric (vitriolic) acid, diluted with the same quantity

of water.

"Oxygenated muriatic acid gas will be instantly disengaged, and perceived in all parts of the room, and will at least destroy any putrid or offensive smell; and I am inclined to hope, that it will likewise correct the contagious effluvia.

"When this gas is extricated in too great quantity, it will excite a cough; but I think that will not be the case with the quantity I have mentioned; if it should, a less portion must be used, or the mixture may be made without heat; but we know that bleachers are continually inhaling this gas in considerable quantity, without any disagreeable consequences. I should think there could be no difficulty in doing it in the house of any poor person; but it certainly might be very easily done in a fever-ward."

As connected with the same subject, and illustrative of the condition of atmosphere produced by the introduction of an infectious ferment, and the means of destroying the noxious compound, I subjoin the following valuable communication from Dr. Samuel Bard, the venerable and learned President of the College of Physicians and Surgeons in the University of the State of New-York.

DEAR SIR,

Hyde Park, July 27, 1803.

I have read, with great pleasure, your arrangement and explanation of contagious diseases, and am, by your arguments, confirmed in the opinion of the agency of a ferment, sui generis, in the propagation of contagious and infectious diseases. I use these terms here indiscriminately: indeed, I believe the analogy between fermentation and its various products, and the progress and fomes of contagious distempers, applies more closely, and to a greater extent, than has been generally supposed.

For instance: under certain circumstances of heat and moisture, all vegetable and animal matters run into fermentation; that of vegetables passes through the stages of vinous and acetous to a species of putrefactive; that of animals likewise has its stages, as is evident in the fermentation of milk; and its products differ conspicuously, according as flesh, fish, fat, blood, or eggs are the subjects of it.

An increased degree of heat always increases the rapidity with which fermentation goes on; and other circumstances of the atmosphere, a greater or less degree of moisture and dryness, a violent storm, thunder and lightning, moonlight, and probably many other less evident causes combining with the heat, variously change, hasten, or retard the process of fermentation, as every person conversant with these subjects well knows.

Again, the different constitutions, (or, if you please, a certain predisposition in vegetable and animal substances,) have the same effect in hastening, retarding, and variously modifying the products of fermentation: thus rich vegetable juices readily assume, and stop at, the vinous stage, and with difficulty can be made to go on to the acetous; poor and crude vegetable juices can hardly be arrested at the vinous stage, but run rapidly into the acetous; and cabbages, and all vegetables of that class, can hardly be made to produce either wine or vinegar, but quickly run into a kind of putrefactive fermentation, Fish putrefies more readily than flesh; and there is a great difference in this respect between the flesh of different animals.

All these circumstances are hastened, rendered more certain, and variously modified, by the addition of a ferment; and, lastly, a certain degree of cold prevents all fermentation, and stops it where it has already begun. So it is with infectious epidemics; certain de