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the influence of the temperature on the progress of the vomito at Vera Cruz; but nothing proves that when the malady has ceased to prevail for several years, a very warm and very humid summer is sufficient to re-produce it; and the heat really does not alone produce what is very vaguely designated by the name of bilious constitution. Notwithstanding the yellow colour which the skin of the patient assumes, it is nowise probable that the bile passes into the blood *, and that the liver and the system of the porta act the principal part in the yellow fever as has been frequently supposed. The black matter in the vomito prieto bears a feeble analogy to the bile : it resembles coffee grounds, and I have sometimes seen that it left indelible stains on linen, or on the wall. It disengages itself from the sulphuretted hydrogen when slightly heated. According to the experiments of M. Ffirth t, it contains no albumine,
* Human bile abounds in albumine : in 1100 parts, it contains 42 of albumine, 58 of resin, yellow matter, soda and salt, and 1000 of water. Thenard in the memoires d'Arcueil, T. i. p. 57.
+ From the experiments made with great care by M. Thenard, there is no bile in the blood of persons attacked with the icterus. M. Magendie who has enriched physiology with ingenious experiments on the action of poisons, has observed that a dog of a moderate size, dies if more than seven grammes of bile is injected into his veins. In this case the serum does not assume a yellow colour, and the
but a resin, or oily matter, phosphates and muriates of lime and soda. The same anatomist has proved from the opening of dead bodies in which the pylorus was totally obstructed, that the matter of the romito is not furnished by the hepatic canals, but is poured into the stomach by the arteries diffused throughout the mucous membrane. He asserts, and the assertion is very remarkable, that we find after death, the black matter still contained in these same vessels *
Some of the physicians of New Spain admit that the epidemics of the comito as well as the small pox, are periodical in the torrid zone, and that the happy time already approaches when Europeans may land on the coast of Vera Cruz, without incurring greater risk than at Tampico, Coro, Cumano, or wherever the climate is excessively warm, and at the same time
conjunctive of the animal remains white. Immediately after the injection, the bile is not recognized in the blood by its savour, although the smallest quantities of bile are sufficient to give a bitter taste to a censiderable mass of water. M. Autenrieth has observed that in man the serum of the blood becomes yellow in diseases which announce no bilious complications (Physiologie, B. ï. p. 93. Grimaud second Memoire sur la nutrition, p. 78.) We know also that the skin becomes yellow in a state of health, with old men, and that it takes a yellowish tint in contusions, and wherever there is extravasated blood.
* Stubbins Firth, p. 37 and 47.
very healthy. If this hope is realised, it will be of the greatest importance carefully to examine the modifications of the atmosphere, the changes which shall take place at the surface of the earth, the draining of marshes, and in a word, all the phenomena which shall coincide with the termination of the epidemic. I should not be surprised, however, that these researches led to no positive result. The beautifal experiments of M. M. Thenard and Dupuytren, have taught us that extremely small quantities of sulphuretted hydrogen mixed with atmospheric air, are sufficient to produce asphyxia *. The phenomena of life are modified by a great number of causes, the most powerful of which escape our senses f. We see diseases arise wherever organized substances, impregnated with a certain degree of humidity and heated by the sun come into contact with the atmosphéric air. Under the torrid zone the smallest marshes are the more dangerous, being surrounded as at Vera Cruz and Carthagena with an arid and sandy soil, which raises the temperature of the ambient air. We may conjecture some of the conditions under which the gazeous emanations which are designated
* A dog is asphyxiated in an air containing two thousand parts of sulphuretted hydrogen.
+ Gay-Lussac, and Humboldt, Exp. sur les princ. constituans de l'atmosphere, p. 25 and 28.
by the name of miasmata are formed, but we are ignorant of their chemical composition. We are no longer permitted to attribute intermittent fevers to the hydrogen accumulated in warm and humid situations; ataxical fevers to ammoniacal emanations; or inflammatory diseases to an increase of oxygen in the atmospheric air. The new chemistry to which we owe so many positive truths, has also taught us that we are ignorant of many things which we long flattered ourselves we knew with certainty.
Whatever be our ignorance respecting the nature of the miasmata, which are perhaps ternary or quaternary combinations, it is not the less certain that the insalubrity of the air of Vera Cruz would be sensibly diminished, if they could but drain the marshes in the neighbourhood of the town; if they could supply the inhabitants with potable water; if the hospitals and church-yards could be removed to a distance*; if frequent fumigations of oxygenated muriatic acid were made in the apartments of the patients, in churches, and especially on board of vessels; and finally, if the walls of the town which force the population to be con
* In 1804 the richest merchants of the town, in order to overcome by their example the prejudices of the lower orders, made a formal declaration that themselves and families should not be interred within the town.
XII.] KINGDOM OF NEW SPAIN. 201 centrated in a small space of ground, and prevent the circulation of air without preventing contraband trade, were to be thrown down.
If on the other hand the government fall upon the extremity of destroying a town, the building of which has cost so many millions ; and if it forces the merchants to settle at Xalapa, the mortality of Vera Cruz will not diminish so much as may at first be believed. No doubt the Negro muleteers or natives of the coast might carry the goods to the farm of l'Encero which is the superior limit of the vomito, and it would not be necessary for the inhabitants of Queretaro and Puebla to descend to the port for their purchases; but the seafaring people among whom the vomito com, mits the most cruel ravages would be always obliged to remain in the port. The persons who should be forced to remain at Xalapa would in fact be those who are habituated to the climate of Vera Cruz, because for a long time their commercial affairs have fixed them on the coast. We shall not examine in this place the extreme difficulty with which affairs which comprehend an annual capital of 250 millions of livres tournois* can be carried on at so great a distance from the port and magazines; for the beautiful town of Xalapa where
* Upwards of €10,200,000 sterling. Trans.