(5 7 ) 
Acid, which fo far aftringes and corrodes its Subftance, 
as to deftroy its Tranfparency. This, Maitrejan con- 
firms by an Experiment of immerging the Cryftalline 
Humour in a Compofition of three Parts Water and one 
of Aquafortis, by which he tells us it may be render’d 
hard and opake but in this Point I cannot help fiding 
with the learned Dr. ' Pitcairn , who has fufficiently 
proved, that there is nofuch Serous Acidity in an animal 
Body. To me nothing feems more eafy than to deduce this 
Opacity of the Cryftalline Humour from an Inflamma- 
tion in the Blood, or an increas’d Momentum in the Fluids, 
with which it is fupply’d : for in that Cafe grofler Particles, 
inconfiftent with the Tranfparency, may be impell’d in- 
to the Lymphatick Vdfels of which it is compos’d:, and 
that there is an Inflammation is fufficiently demonftra- 
ted from hence ^ firft, the Patient feels often a pungent 
Pain in the Eye, which as it is generally the forerunner 
of a Catarad, fo it certainly indicates an Inflammation of 
the Part. Secondly, Thofe Macula , which appear as 
it were fwimming in the Air, plainly prove that there are 
opake Particles already enter’d the Lymphatick Veflels, 
which compofe the Vitreous Humour. 
Thirdly, the Iris , whofe Colour arifes from the 
Blood Veflels, as it changes from a lighter to a darker 
Colour, fhews the Violence of the Inflammation, and is 
therefore efteem’d a Symptom of the worft Confequence c 
FINIS . 
L 0 N D 0 N : Printed for W. and J. Inn Y s>. 
Printers to the Royal Society, at the Weji End of 
St, Paul’r Churchyard, 
