“In regard to the time requisite for the complete evaporation of the infectious aura, in what proportionate gradation its activity is impaired by ventilation, and the specific quantity required to produce effect on the human body, they are matters which I apprehend will not readily be admitted to be clearly and certainly known. That the first porters were not taken ill before the 23d of June, is very true; but that the goods had been airing and purifying for twenty-six or twenty-eight days, has been shown above to be an error. The Doctor also makes two other suppositions equally erroneous. The first, that the whole of the cotton contained in a number of bales is equally imbued with infectious aura; the second, that all the bales of a ship’s cargo are opened nearly about the same time. But, as the cotton contained in these bales may not only have been collected from different villages at different times, but packed up under various circumstances relative to the materials used for embalage, and the persons employed in embaling or steeving them; it may easily be conceived how the cargo of a ship, coming even from a place where the plague actually rages, may be only partially infected, or not infected at all. The warmest advocate for contagion never contended for every bale of a ship’s cargo being equally infectious. As to the airing of the bales, it is a laborious and a tedious process. Where there is a considerable number, it takes up several days to open and arrange them, goods of different kinds must be disposed separately, accounts taken, and the cordage, &c. laid up with care where it may be found again. The laborious part of these operations is performed by the porters, who also transport the goods from the water side to the enclosure where they are to be aired: and, as the days of quarantine do not begin to be reckoned till all the goods are landed, the porters for some days at the beginning are sufficiently employed in receiving and arranging the cargo, that being the business requiring the first dispatch. When these circumstances are considered, it will appear no extravagant supposition, that some of the last opened bales of Chataud’s cargo might still retain enough of infectious aura to infect the porter on the 23d of June. To set this retardment, almost unavoidable in the opening of bales, in a still clearer light, it should be observed, that, by the regulations at Marseilles, all suspected goods are subject to what is termed _sereines_; that is, a certain number of bales are taken out of the hold, and, being opened at both ends, are exposed to the air for two, three, or six days, by way of trial, in order to see if any signs of infection should appear among those employed in handling the merchandise. When these have been aired, more or less, according to circumstances, another parcel is opened and exposed to ventilation in like manner: so that, according to the burden of the ship, there may