of a Leather Strap : Voltaic Series. 127 



It is no other than a leather strap, which connects two 

 drums in a large worsted mill in the town of Keighley. 



The dimensions and particulars of the strap are as follows: 



It is in length 24- feet 



Breadth , 6 inches 



Thickness i do. 



It makes 100 revolutions in a minute. 



The drums, over which it passes at both ends, are two feet 

 in diameter, made of wood fastened to iron hoops and turnino- 

 on iron axles; these drums are placed at 10 feet distance from 

 each other, and the strap crosses in the middle between the 

 drums, where there is some friction ; the strap forming a figure 

 of eight. There is no metal in connexion with the strap, but 

 it is oiled. If you present your knuckle to the strap above the 

 point of crossing, brushes of electrical light are given off in 

 abundance, and when the points of a prime conductor are held 

 near the strap, most pungent sparks are given off to a knuckle 

 at about two inches ; I charged a Leyden jar of considerable 

 size in a few seconds by presenting it to the prime conductor. 

 Thegendeman who told me of this curious strap has frequent- 

 ly charged his electrical battery in a very short time from it, 

 and he informed me that it is always the same, generating 

 electricity from morning to night without any abatement or 

 alteration. If this strap had the advantage of silk flaps and a 

 little amalgam, it would rival the machine in the lecture room 

 in Albemarle-street. 



Pray excuse the earnestness of 



Your most faithful Servant, 

 Keighley Rectory, Yorkshire, Theodore Dkury. 



Dec. 17, 1838, 



XXIV. On Voltaic Series and the Comhinatio7i of Gases hy 

 Platinum. By W. R. Grove, Esq. M.A. 



Gentlemen, Swansea, Dec. 14, 1838, 



TN a letter on an ccconomical constant battery which you 

 did me the honour to publish in your number for the present 

 month, (Dec. 1838. vol. xiii. p. 4.30) I ventured to suggest the 

 more extensive employment of the porous septum as an instru- 

 ment of analysis for voltaic combinations. I am not unaware 

 of the experiments of De la Rive, Porret, &c., and meant to 

 allude less to its use in the decomposing cell, than in the trou'di 

 itself, and to its practical application to the improvement of ap- 

 paratus. The following experiments instituted with this view 

 may not be uninteresting to your readers; they difler, it will 



