CLASS II. 1. 3. OF SENSATION. 1$3 



coagulates; and is said to be dissolved, and is by some supposed 

 to be in a state of actual putrefaction. See Sect. XXXIII. 1. 

 3. where the truth of this idea is controverted. But in the fevers 

 of both this genus and the preceding one, great heat is produced 

 from the chemical combinations in the secretions of new vessels 

 and fluids, and pain or uneasiness from the distention of the old 

 enes; till towards the termination of the disease sensation ceases, 

 as well as irritation, with the mortification of the affected parts, 

 and the death of the patient. 



Dysenteria, as well as tonsillitis and aphtha, are enumerated 

 amongst the diseases of external membranes, because they arc 

 exposed either to the atmospheric air which is breathed and 

 swallowed with our food and saliva; or they are exposed to the 

 inflammable air, or hydrogen, which is generated in the iutes- 

 tines; both which contribute to produce or promote the conta- 

 gious quality of these fluids; as mentioned in Class II. 1. 6. 



It is not speaking accurate language, if we say, that, in the 

 diseases of this genus, the fever is contagious; since it is the ma- 

 terial produced by the external membranes which is contagious, 

 after it has been exposed to air; while the fever is the conse- 

 quence of this contagious matter, and not the cause of it. As ap- 

 pears from the inoculated small-pox, in which the fever does not 

 commence, till after suppuration has taken place in the inoculat- 

 ed arm, and from the diseases of the fifth genus of this order, 

 where contagion exists without fever. See Class II. 1. 5. and 

 II. 1.3. 18. 



The existence of contagious miasmata in the atmosphere was 

 believed even in the time of Homer, and was allegorized under 

 the title of the arrows of Apollo. See catarrhus contagiosus, II. 

 1. 3. 6. Of these it is probable, that some contagious matters 

 are only diffused in the atmosphere, as that of the small-pox, as it 

 seems only to infect those who are very near the variolous pa- 

 tient; and seems to be swallowed with the saliva, and thence to 

 affect the tonsils. Other contagions may be dissolved in the at- 

 mosphere, as that of the measles, and of epidemic catarrhs, which 

 therefore first affect the membranes of the nostrils in men, and of 

 the maxillary sinuses also in dogs and horses. 



Contagious materials have been also believed from remote an- 

 tiquity to lodge in the walls of rooms where the sick have been 

 confined; as in the wards of hospitals, jails, ships, as well as in 

 the bedding or clothes of the infected* The methods of purifying 

 infected houses seem also to have been studied in the remotest 

 times; the Levitical law directs the walls of the house of a leprous 

 person to be scraped; and in modern times white-washings with 



