OS THE ELECTRIC COLUMN. 03' 



npparatusses ; but the elecfric matter moves easily along its 



BurFace, as I have visibly shown by the Lichtcnberg figures 



produced on its naked surface, where they dissipate in a 



littie time, while they last many days on resinous surfaces. 



This is the reason of covering the glass pillars destined to Varnishes dif- 



insuhite with some resinous varnish; but all these varnishes tJs* ^ ^'^°^^'* 



are not equally fit for the purpose, and this is one of the 



objects of the following process, as well as the trial of the 



different conducting faculties of other bodies. 



For tlsese experiments, the bodies to be tried must be Trials of th? 

 reduced into slips or rods, which are to be laid on the powersof bo- 

 hooks, 5 and 6, of the column, in order to observe the ef- dies, 

 feet produced on its electroscopes', but there are necessary 

 precautions to be used in laying them on the hooks. For 

 instance, in respect to the bodies with which I shall begin, 

 4hose which have different conducting faculties, belonging 

 mostly to the vegetable and animal kinds, when they are 

 placed on the hooks with t^e fingers, as it is almost impos- 

 sible to lay them on both Looks at the same instant, the end 

 which touches first disturbs the equilibrium of the electric 

 fiuid in the coliLmn; and I have shown above, that it is but 

 slowly restored. In order to obviate this defect, and for 

 another purpose that will follow, two brass wire brackets, 

 12, 12, are fixed in the front of the base of the instrument, 

 on which the slips are first laid, and there taken up by 

 two glass hooks covered with sealing wax, with which they 

 are placed on the hooks of the column, I shall give a gene- 

 ral idea of these trials under the following head. s 



Exp. 11. The substances of this class having more or Exp. n. 

 less conducting faculty, they lessen in diiferent degrees the 

 divergence 'n\ the electroscopes, by transmitting more or less 

 electric fiuid from A to B. This is a curious kind of ex- 

 periments, but as the partic ilars are not here my object, I 

 •hall relate only one^ concerning the physiology of vegeta- 

 bles, which may lead to others of the same kind. Having 

 repeated in presence of Dr. Lind these experiments on the 

 different conducting faculties of various bodies, I showed 

 him a phenomenon, which had surprised me. A thin slip Difference in 

 o^ deal, cm along the fibres, being applied to the aolumji, ^^^^^ ^ ^J^q^^' 

 there remained but little divergence in the electroscopes ; 

 wh^ileaslip of the same wood, of the same thickness and 



breadth, 



