376 Mr. Sturgeon on some Magneto-electrical Experiments. 



your Magazine has the appearance of a cloudy surface, the 

 separation of the lines being scarcely distinguishable. 



If now I employ convex lenses, I find that by using a lens 

 of two inches' focus, I can read your Magazine with perfect 

 ease, the letters appearing black and distinct. 



I pretend not to offer any explanation of these phenomena, 

 but as the facts may be relied upon, their statement may pos- 

 sibly tend to promote further inquiry on so interesting a sub- 

 ject. One practical advantage may be drawn from them, viz. 

 that where the power of reading is unhappily lost by amaurosis 

 of both eyes, it may possibly be restored by the use of a con- 

 vex lens of about two inches' focus. 



I may add, that with the diseased eye I am able to per- 

 ceive the outline, though not the details, of the objects around 

 me. 



I am, Gentlemen, yours, &c. 



London, Oct. 1834. K. 



LIII. Account of some Magneto- electrical Experiments made 

 with the large Magnet at the Exhibition Room, Adelaide- 

 street. By Mr. Sturgeon. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



tTAVING obtained permission of the proprietors of the 

 ™ ■* Exhibition Room, Adelaide-street and Lowther Arcade, 

 to employ their large magnet in any new experiments which 

 I might wish to undertake, I availed myself of that privilege 

 for the first time on Thursday evening the 28th of August 

 last. The following results were produced. 



The decomposition of hydriodate of potassa in solution : 

 First, by paper moistened in it placed on a platinum plate at- 

 tached to the negative side of the circuit; and with a platinum 

 point connected with the positive side, the upper part of the 

 paper was occasionally touched, whilst the magnet was at 

 work. At each touch, however short the interval, iodine was 

 evolved at the positive point. 



Second : a solution of the hydriodate and starch was placed 

 in a rectangular glass box, with a gauze partition to separate it 

 into two compartments. A platinum plate, properly con- 

 nected, was placed in each compartment. In half a minute 

 the positive cell was completely obscured by liberated iodine. 

 A more striking experiment was never exhibited. Platinum 

 wires, properly connected in the circuit, were placed in solu- 



