ue 



KtECTRIC At MA^^INE. 



two boards, where it is kept till it is again dry. Thus it Is 

 rendered very flat, and its edge very fliarp, and all its parts 

 will apply to the furface of the glafs. This piece of leather 

 is covered with another a little broader, the rough furface of 

 which is towards the glafs, and its lower edge on the fide to- 

 wards which the plate moves ; and its upper edge on the 

 other fide from which the plate moves, being likewife very 

 Iharp. The piece of filk is applied with accuracy to this 

 leather. Before it is fattened on, it is heated, and befmeared 

 firft with butter of cacao, then with a large quantity of Kieirt- 

 mayer's amalgam*; and after it is fattened on, it iscompreflfed 

 in conjun6tion with the wood, or prefled ftrongly againft the 

 machine. The leather is next covered with amber varnilh, 

 amalgam is fpread over this, and after the varnifli is dry, it is 

 fmoothed with a burnittier. This is repeated feveral tinies. 

 The whole being very dry, and the rubber being prefled fo as 

 to touch the glafs in all points, the leather coated with amal- 

 gam is covered with a piece of fine white paper, as long as 

 the leather, and half an inch broader, fo as to cover the fearti 

 that fattens the lilk to the leather, and the paper is fattened 

 to the wood above or below, accordingly as it is on the afcend* 

 ing or defcending fide of the plate. 



Dry paper is known to be capable of acquiring a high flate 

 of eledlricity, which induced me to try this fiibttance as an 

 immediate rubber. The following are the advantages, that 

 by my experiments, repeated and varied in a great number 

 of ways, I have found paper employed as a rubber to poflefs 

 over every other known fubftance. 



1. The glafs is not rendered dull by the fridlion, as happens 

 at length, and by frequent ufing, when it is4tt ifiimediate 

 contaft with the amalgam, 

 does not be come 2. By the immediate cental: of the amalgam, the glafs fre- 

 fireaky, quently contrads ftreaks here and there, that occafion a 



circulation of the fluid. This cannot take place in the con- 

 ftruclion I propofe. 



3. Neither the glafs nor the filk can be foiled. It is well 



known, that (he cleannefs of the glafs, as well as of the 



nefs of the whole rubber and the whole machine in general, is of importance in 



machine ad- 



Tanug^otts. « I add to this ama]g*m as much filver, as the mercury can dif» 



ibUe in conjunflion with the zinc. 

 ' ' 3 producing 



The rubber 

 covered with. 

 fine white 

 paper. 



What led to 

 thisv 



Its advantages. 



The ghfs not 

 rendered dull. 



and neither it 

 nor the filk is 

 foiled. Clean 



