236 HOSACK ON THE LAWS OF CONTAGION. 



bade intercourse with the infected portion of our city, and ordered an 

 abandonment of that part of the town, threatening violent measures if 

 their orders were not immediately complied with. In a short time 

 after, the infection extended a few streets further; the board of health 

 again defined its limits, and again declared that still not a case had 

 occurred that could not be traced to this part of the city as its source.* 



Will not the same assimilating or fermentative process furnish the most 

 satisfactory solution of the fact noticed by Boerhaave, Cullen, Lind, 

 Russell, and many others, that fomites are more to be dreaded than 

 the excretions alone proceeding from the diseased body? Not, how- 

 ever, in the manner those authors suppose, that such fomites acquire 

 greater virulence ; but, that by the same process the specific poison has 

 been more extensively multiplied by means of the atmosphere and foul 

 excretions which are involved in the clothing worn by the sick ; and that 

 by the same means the danger of the infection has been increased in the 

 same degree that the poison has been multiplied. As a further evi- 

 dence, too, that the contagion is multiplied, but not more concentrated, 

 as those writers have imagined, it is a fact established by every writer 

 on those contagious diseases, that the first cases of every epidemic are 

 uniformly the most fatal; but that, as the season advances, the danger 

 of taking the disease is increased, while the disease itself has, perhaps, 

 become even milder than it was in the commencement. 



Let me further ask, do not the processes lately introduced for disin- 

 fecting the air by means of the fumes of the acetic acid, the oxygenated 

 muriatic acid gas, the nitric, and sulphuric acid vapours, operate by 

 making new combinations with some of the ingredients constituting the 



* Chisholm's Letter to Haygarth. — See Note L. 



