120 On the Phcenomena of Platinum 



line lens ; on the contrary, I think that a convex glass of a less 

 magnifying power than that usually required after the removal of 

 cataract, may he frequently employed to great advantage in 

 cases of conical cornea. 



Were any further arguments than those adduced necessary to 

 prove that the short sight of the patient is occasioned by the 

 morbid thickness of the cornea, and not by the superabundant 

 quantity of the aqueous humour, as has been supposed, it would 

 be, the well-known fact, that water possesses little comparative 

 refractive power ; while, from the dense structure and the form 

 of the conical cornea, it is as evident that its powers of refraction 

 must be very considerably increased. Indeed, giilta sercrni would 

 certainly be produced by the backward pressure of a superabun- 

 dant quantity of aqueous humour against the vitreous Inunour 

 and retina, long before it would occasion a protrusion of so dense 

 and firm a tunic as the transparent cornea ; and I have actually 

 seen giilta serena result from this cause, without any material 

 convexity of the cornea being perceptible, although from over- 

 distention it felt to the touch nearly as hard as an egg-shell. 



Although I may have failed in convincing my readers of the 

 accuracy of some of the opinions which I have ventured to sub- 

 mit in this paper, yet 1 have the gratification of knowing that I 

 have fully proved the important fact, of having successfully carried 

 into effect a mode of treatment capable of restoring vision in a 

 case incurable by other surgical means, and which, as far as I 

 have been able to ascertain, has hitherto never been employed 

 by any other person. 



XXVIII. On the Phcennrnena of Platinum and other Wires in 

 inflammable Media. 



To Mr. Tillocli. 



Sir, — x\.DMiRiNG, as I did, the important and beautiful com- 

 munication of Sir H. Davy on the Phenomena of Platinum Wire 

 and that of Palladium in some inflammable Media, it may not 

 be uninteresting for you to receive an account of my experiments. 

 *' Experimentum fiat" is the impression which will ever govern 

 my philosophical studies; and seeing that the noblest erection of 

 theory which the human mind can rear, must yield the prece- 

 dency to a single fact established by the hand of experiment, I 

 shall in the present imposing march of chemical discovery be 

 fearful of trusting to the illusions of fancy, and tegard with a 

 jealous eye the portraiture drawn by the pencil of hypothetical 

 dogma. 



l.Plati- 



