54 



is, however, a mistake, for both are pus (ori- 

 ginating in the coloured blood, which, during 

 inflammation, is carried into the capillary ves^- 

 sels) which exudes on the membrane of the tra- 

 chea, mixed with mucus, but whicli in the cellu- 

 lar texture has no other outlet, than that, which it 

 can procure to itself by the dissolution of the ad- 

 joining parts; hence, when chemically analysed, 

 it must be found to contain more constituent 

 parts, than the matter produced on the mucous 

 membrane. I am convinced, that by a proper 

 comparative examination, the difference might 

 be discovered, and the physician enabled, through 

 the analysis of the expectorated matter, to deter- 

 mine whether it proceeds from an open ulcera- 

 tion, or is formed only in the mucous membrane. 

 But, hitherto, we have no such examination. 

 GEORGE PEARSON has indeed lately described 

 the different varieties of the expectorated mu- 

 cous matter, and fully examined the relation of 

 the different kinds to heat, water, spirits, and ace- 

 tic acid ; he has alsp made some attempts toward 

 their analysis, which evince both attention and 

 diligent research ; but as lie could not know some 

 of the substances, which are generally found in 

 animal humours, and as he seemed to want the 

 experience, \* hich in every research is so neces* 



