52 PRACTICE OF PHYSIC. 



ing everywhere the surface of the pleura, and particularly those 

 parts where the lungs adhere to the pleura costalis, or medias- 

 tinum ; and this crust seems always to be the cement of such ad- 

 hesions. 



The same exudation shows itself also by a quantity of a ser- 

 ous whitish fluid, commonly found in the cavity of the thorax ; 

 and some exudation or effusion is usually found to have been 

 made likewise into the cavity of the pericardium. 



" These two states, effusion and adhesion, are matters of 

 fact, and past all doubt. In the three following paragraphs I 

 add others, which are at least probable, and which are proper 

 matters of inquiry and speculation for you. 1 ' 



CCCXLVIII. It seems probable, too, that a like effusion is 

 sometimes made into the cavity of the bronchiae : for, in some 

 persons who have died after labouring under a pneumonic in- 

 flammation for a few days only, the bronchiae have been found 

 filled with a considerable quantity of a serous and thickish 

 fluid ; which, I think, must be considered rather as the effu- 

 sion mentioned having had its thinner parts taken off by respir- 

 ation, than as a pus so suddenly formed in the inflamed part. 



CCCXLIX. It is, however, not improbable, that this effu- 

 sion, as well as that made into the cavities of the thorax and 

 pericardium, may be a matter of the same kind with that which, 

 in other inflammations, is poured into the cellular texture of 

 the parts inflamed, and there converted into pus ; but, in the 

 thorax and pericardium, it does not always assume that appear- 

 ance, because the crust covering the surface prevents the ab- 

 sorption of the thinner part. This absorption, however, may 

 be compensated in the bronchiae by the drying power of the 

 ah* ; and therefore the effusion into them may put on a more 

 purulent appearance. 



In many cases of pneumonic inflammation, when the Sputa 

 are very copious, it is difficult to suppose that the whole of 

 them proceed from the mucous follicles of the bronchiae. It 

 seems more probable that a great part of them may proceed 

 from the effused serous fluid we have been mentioning ; and 

 this, too, will account for the sputa being so often of a purulent 

 appearance. Perhaps the same thing may account for that pu- 

 rulent expectoration, as well as that purulent matter found in 



