Properties of Bees' -wax and Lead Cloride. 137 



electricity like a metal (that is, without decomposition) — a 

 conclusion, however, which at first sight would appear to be 

 negatived by certain experiments of M. Wiedemann published 

 in Pogg. Ann. eliv. 318-320, from which he found that the 

 resistance of lead chloride diminished by increase of tempe- 

 rature. 



I first had made a small carbon box containing a carbon 

 plate, but prevented from touching it by three small pieces of 

 clean glass. The carbon plate had a carbon electrode attached 

 to it, the whole being cut out of a solid piece of carbon so as 

 to have the shape of an inverted T. Into the box lead chloride 

 was poured in a fused state until it covered up the plate, but 

 leaving the carbon electrode of the plate protruding for con- 

 nexion with the battery. The whole was then allowed to cool 

 very slowly. The outer part of the carbon box and the end 

 of the carbon electrode were now electrotyped, and copper 

 wires soldered on, the junctions of the carbon and copper being 

 quite clear of the lead chloride. 



With this condenser the results given on the next page were 

 observed. 



In addition to the resistance of the condenser being mea- 

 sured while the battery was connected, time-readings were 

 also taken with the galvanometer of the discharge from the 

 condenser after the removal of the battery, as well as time- 

 readings with an electrometer of the electromotive force in 

 the condenser producing the discharge. As, however, the 

 diminution in the discharge-deflection was in each case quite 

 regular, the curves are not given. 



It is interesting to observe in the Table (p. 138) that in 

 every case there is a diminution of resistance by electrification, 

 although in some cases there was an increase during the first 

 minute. Looking at the first group of tests, taken between 

 November 13th and 15th, we see a gradual increase in the 

 resistance day by day. Looking also at the second group 

 made between November 21st and December 1st, we likewise 

 see a steady daily increase in the resistance ; but in the interval 

 between November 15th and 21st, when no tests were made, 

 there appears to be a decided diminution in resistance. Con- 

 sidering, however, that the tests taken on November 13th, at 

 the beginning, and on December 1st, at the end of the inves- 

 tigation, give almost identical results, it cannot be concluded 

 with certainty that there was any decided deterioration taking 

 place in the lead chloride. But on breaking up the condenser, 

 the lead chloride was found to contain many small holes ; so 

 that it is possible that damp may have collected in these. 

 This solution, however, would at first sight appear to be rather 



