INFLAMMATIONS. 29 



vitriol or sugar of lead. It is commonly employed in the form 

 of the coagulum aluminosum, but I have found the solution in 

 water to be still more effectual, employing from two to five grains 

 of alum to the ounce of water. 



The astringent powers of the preparations of copper have es- 

 pecially appeared in the application of them to the eyes, and we 

 have known a weak solution of verdegris useful in restraining 

 inflammation ; but it is so ready to prove irritating to that sen- 

 sible organ, that a great deal of nicety is necessary in the em- 

 ployment of it ; and we seem to have a milder preparation in 

 the aqua sapphirina. 



It has been commonly supposed that the aqua sapphirina was 

 suited to take off specks or opaque spots that appear upon the 

 cornea, and which has been supposed to imply an escharotic 

 power ; but this certainly is seldom the case, and it seems to act 

 only by an astringent power, diminishing the impetus of the 

 fluids in the vessels which terminate in the opaque spot. M.M. 



CCLXXXVII. In the cure of Ophthalmia, much care is 

 requisite to avoid all irritation, particularly that of light ; and 

 the only safe and certain means of doing this is by confining the 

 patient to a very dark chamber. 



" It is obvious that light cannot be admitted without occa- 

 sioning more or less motion in every part of the eye ; it not only 

 necessarily occasions the different motions of the iris, and those 

 of the palpebrae constantly corresponding to them, but we know 

 that no part of the human body moves so frequently as the eye ; 

 it requires an effort to keep it fixed but for a moment, and it is 

 impossible to suppose any illapse of light, that does not occasion 

 a constant motion of the whole eye, and therefore affect every 

 part in which an inflammation may be seated. 



" But light also operates in another manner. If the sensi- 

 bility of the retina is any how increased, then light is a very 

 strong irritation, and we may suppose this to be the case in the 

 deep seated inflammations of the retina or choroidea. This inter- 

 nal inflammation is of more rare occurrence ; but even a slight in- 

 flammation of the adnata, though not sufficient to communicate an 

 inflammatory state to the internal membranes, can give such' a 

 tension to their vessels, as will greatly increase their sensibility, 

 so that the slightest irritation of light will be extremely hurtful, 



