VOL. LXXXV.] VHILOSOPHICAL TRANSACTIONS. 547 



On seeing a body opened some time ago, where there was a great collection of 

 water in the cavity of the thorax, I observed that the surface of the lungs was 

 covered with a whitish crust. I remarked to a friend, that I thought this crust 

 was owing to some combinations which had taken place between the lungs or 

 pleura and the serous fluid effused, similar to what I had observed between flesh 

 and water; or that the serous fluid had acted on the coagulable matter, and had 

 produced a similar change. Dr. Cleghorn mentions a circumstance, which in 

 some measure seems to agree with the observation then made. As the fact is a 

 curious one, I shall subjoin the following extract. He is speaking of abscesses 

 formed in the lungs. " These abscesses had sometimes emptied themselves into 

 the cavity of the thorax, so that the lungs floated in purulent serum, their ex- 

 ternal membrane, and likewise the pleura, being greatly thickened, and con- 

 verted as it were into a white crust, like melted tallow become cold." In a note 

 he says, " I am now doubtful if this crust was the pleura and external coat of the 

 lungs, changed from a natural state by soaking in a purulent fluid, and if it was 

 not altogether a preternatural substance, formed by fluids deposited on those 

 membranes, and compacted together by the motion of the lungs." 



Much has been said by many authors on the subject of secretion. It was at 

 one time supposed that it depended on some peculiar property of the living prin- 

 ciple; audit was thought impossible to form any secretion but through the 

 medium of secreting organs. M. Fourcroy has however contradicted this, by 

 the experiments where he forms bile. Spermaceti is an animal substance, se- 

 creted in a particular species of whale, and the substance formed in the fore- 

 going experiments, as far as I can judge, agrees with it in every particular. M. 

 Fourcroy says, that M. PouUetier de la Salle found a crystallized inflammable 

 substance similar to spermaceti in biliary calculi. May not the suety matter in 

 steatomatous tumours arise from something of this kind ? 



By attending to the various secretions of the body, by examining their com- 

 position in the healthy and morbid states of the system, may we not expect to 

 derive great advantage, particularly when accurate experiments are applied 

 towards the relief of disease ? Some excuse may perhaps seem necessary for 

 the little attention which has been paid to the accurate results in the different 

 experiments; particularly so, as the analysis of every part of the animal body, 

 except the bones, is at present so incomplete; but I hope that the time necessary 

 for my medical pursuits, and the want of a complete chemical apparatus, will 

 not render the simple facts I have here related less useful. I have not attempted 

 to account for the various phenomena which appear in the experiments, because 

 the facts seem too few to admit of any general conclusion. 



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