ADDITIONAL NOTES ON CONTAGION. 273 



prisoners in other apartments of the bridewell. The progress of the disease, which I 

 have thus briefly noticed, was arrested by the removal of the sick, and the materials im- 

 pregnated with the morbific poison ; by the introduction of pure air, by ablution, and by 

 other means now most generally had recourse to for the purification of fever-wards and 

 houses of recovery, as recommended by Dr. Ferriar. 



" It has again and again been observed, by the keepers of our prisons, that those crimi- 

 nals who have long been accustomed to breathe the vitiated air of the crowded apart- 

 ments of these institutions very frequently escape febrile contagion: the poison itself 

 might, at first view, appear to have lost a portion of its virulence ; but it has with more 

 propriety been maintained that the individuals thus inured to its influence are, from habit, 

 exposed to it with impunity ; while, on the other hand, the reverse is the case with the 

 unassimilated, when subjected to the operation of an impure air, deriving its noxious pro- 

 perties from concentrated human effluvia. It is a remark of most writers, that the in- 

 fection of typhus, whether occurring in jails, ships, or elsewhere, becomes concentrated, 

 and, consequently, more active by the cold of winter. This opinion is strengthened by 

 the well-known fact, that a greater number of deaths takes place from fevers of this 

 nature, in our prisons, during the winter than in the summer season." 



NOTE H. (Seepage 232.) 



I have expressed the belief that the changes which the atmosphere undergoes during 

 (he prevalence of certain pestilential disorders are ascribable to a fermentative or assimi- 

 lating process. I am strengthened in this opinion, which I have for many years maintained, 

 by the recent and elaborate investigations of MM. Gay-Lussac, De Saussure, and other 

 distinguished chemists, which have thrown much light upon the subject of fermentation, 

 and also by some interesting observations lately published in the Edinburgh Review. 

 See Edinburgh Review for April, 1814. 



For a perspicuous elucidation of the manner in which the poison of diseases of specific 

 contagion operates upon the human constitution, in assimilating the mass of fluids to its 

 own peculiar nature, the reader may consult an Essay lately published by Dr. J. W. 

 Francis, Professor of Materia Medica in the University of the State of New-York, and 

 inserted in the American Medical and Philosophical Register, (vol. 4. p. 474 — 519:) 

 also a valuable Dissertation on the Pathology of the Human Fluids, by Dr. Dyckman, 

 of New- York. 



37 



