Resistance by Fluids to Electrie Conduction. 37 
sulphate of copper, free from this varying influence, has been 
measured.* i 
_ As T wished to know the conducting power of several other 
liquids, I embraced the opportunity offered to me in Prof. Buff’s 
Physical Cabinet at Giessen, to enter upon a proposed: investi- 
gation, having this end in view. It was unfortunately impos- 
sible for me to complete the labor which my original plan em- 
braced, before the time fixed for my return to America. Well 
wishing friends have neveriheless advised me to publish the 
essential results of my investigation, since several of them may 
have a practical value. 
The apparatus and general facilities for this investigation, and 
above all the counsel of Prof. Buff-in the difficulties which were 
constantly presenting themselves, were extended to me in the 
Same spirit of generosity that distinguishes the great leader of 
the Chemical School at this University. 
_ For the reception of the fluids, whose bearing against the elec- 
tric current was to be proved, I employed a rectangular trough of 
thick, firm wood 0:3 meter long, 0075 meter wide, and of 
0-075 meter in depth. The interior was thickly overspread with 
Shellack varnish to prevent, or as long as might be, delay the ab- 
Sorption of liquids. Upon this trough lay the blocks, of which 
one was fixed, the other movable. They served to hold the 
plates that sink into the liquid, and to regulate at pleasure their 
distance from each other. ‘The plates equal in area to the cross 
Section of the trough, were secured to copper plates, which were 
Made fast to the blocks, and put in connection with the termini 
of the electromotor. 
* Fora battery, the constant coal and zine pairs of Bunsen, from 
one to several in connection, were employed. ‘The mtensity of 
the current was measured with an exceedingly accurately con- 
intain a current of un- 
Th 
_ 
Structed Weber’s galvanometer. To maintain 
changing strength, a Wheatstone’s Regulator was used. 
wire of the latter was of German silver, whose conducting power, 
the distance of the two plates was increased by carry- 
e movable one, and the amount of German silver 
Silesia OOO 
Ware ek ~ be aon 
. is: ee Le= a 
ee ae ee id. xliv, 349. 
foo sf es 
