224 PHILOSOPHICAL TRANSACTIONS. [aNNO 1758. 



these cases blistering will produce remarkably good effects, and far from increas- 

 ing, will generally lessen the frequency of the pulse and fever, more speedily 

 than any other remedy. 



On the other hand, when the fever and frequency of the pulse proceed from a 

 true inflammation of the lungs, from large obstructions tending to suppuration, 

 or from an open ulcer in them, blisters will be of less use, nay sometimes will do 

 harm except in the last case, where they, as well as issues and setons are often 

 beneficial, though seldom able to complete a cure. But as in pituitous infarc- 

 tions of the lungs, with cough and fever, repeated blisters applied to the back 

 and sides are far preferable to issues or setons, so these last seem most proper in 

 an open ulcer of the lungs. The former make a greater and more sudden deri- 

 vation, and are therefore adapted to acute cases ; the latter act more slowly, but 

 for a much longer time, and are therefore best suited to chronic diseases. Fur- 

 ther, while blisters evacuate chiefly the serous humours, issues and setons ge- 

 nerally discharge true purulent matter, and on this account may be of greater 

 service in internal ulcers. 



In what manner blisters may lessen the fever and frequency of the pulse at- 

 tending internal inflammations. Dr. W. had endeavoured to explain in his Phy- 

 siological Essays, p. 69 ; and only adds here, that in the cases above recited, 

 where the quick pulse and feverishness proceeded more from a pituitous infarction 

 than a true inflammation of the lungs, blisters, by relieving this organ in some 

 measure of the load of humours oppressing it, would render the circulation 

 through its vessels freer, and consequently lessen the quickness of the pulse, and 

 other feverish symptoms. 



It might not, however, be improper briefly to point out the reason, why 

 blisters which have been observed to be remarkably efficacious, even when early 

 applied in pleurisies,* are less so in true peripneumonies. This difference he 

 imagined might be accounted for from there being no immediate communication 

 between the pulmonary vessels and those of the sides and back, to which the 

 blisters are applied ; whereas the pleura and intercostal muscles are furnished 

 with blood-vessels from the intercostal arteries, which also supply the teguments 

 of the thorax: so that while a greater flow of serous humours, and also indeed 

 of red blood, is derived into the vessels of the external parts to which the ve- 

 sicatories are applied, the force of the fluids in the vessels of the inflamed pleura, 

 or intercostal muscles nmst be considerably lessened. Further, as the inter- 

 costal muscles and pleura are, as well as the teguments of the thorax, supplied 

 with nerves from the true intercostals, blisters applied to the back and sides may 

 perhaps, on this account, also have a greater effect in relieving inflammations there 



• Dr. Pringle's Observations on the Diseas<;s of the Army, part iii, chap. Q, 



