﻿Dr. Paalzovv on the Galvanic Resistance of I A quids, 271 



the powdery form described in the paper referred to above. The 

 mineral is reported to be most abundant in a " black band " of 

 gypsum, and to be met with in nodules which .are sometimes 

 very much larger than any seen by myself near Windsor ; a good 

 deal is said to have been thrown away by the quarrymen as being 

 of no value compared with the plaster ; this is worth about 90 

 cents a ton, shipped, while the borate would probably realize 

 nearly as many dollars, or, roughly, be a hundred times as 

 valuable. It was mentioned in the paper already twice alluded 

 to, that, from what I had observed, the lowest beds of gypsum 

 would probably afford the largest quantity of this mineral and 

 its fellow borate : the new locality, as I understand, is one of 

 those where the lowest members of the carboniferous series con- 

 taining beds of gypsum are found. 



XXXVI. On the Galvanic Resistance of Liquids. 

 By Dr. Paalzow"*. 



^^HE first trustworthy values for the galvanic resistance of a 

 liquid (that of sulphate of zinc) are contained in a paper 

 by Beetzf. The paper also contains the reasons for placing no 

 confidence in previous statements obtained by other methods. 

 It is only by the combination of zinc with sulphate of zinc, which 

 Beetz made use of, that it is possible to avoid polarization and 

 other changes of the electrodes as well as of the adjacent elec- 

 trolytes. 



I proposed to determine the resistance of other liquids as well 

 as of sulphate of zinc, retaining, however, unpolarizable elec- 

 trodes and their advantages. 



In order more clearly to detect a possible influence of the 

 chemical nature of the liquid on the resistance, I made the solu- 

 tions of the acids and salts under investigation in chemical equi- 

 valents ; for it may be reasonably supposed that such an influ- 

 ence exists, as the conduction of electricity in liquids is always 

 accompanied by chemical decomposition. 



I then also examined the resistances of mixtures of saline 

 and acid solutions in water with equal equivalents of water, in 

 order to decide whether the current divides in accordance with 

 Ohm's law. 



In order, moreover, to ascertain whether there is with elec- 

 trolytes, as with metals, a connexion between the conduction for 

 heat and for electricity, I investigated the conducting- powers 

 for heat of certain liquids whose galvanic resistances were known. 



* Translated from the Berlin Monatsbericht, July 1868. 

 t Poggendorff's Annalen, vol. cxvii. p. 1. 



