20 
Proceedings of Eoyal Society of Edinlurgli. [sess. 
A Preliminary Communication on the Electrical Resist- 
ance of Various Urines. By Dawson Turner, M.D., 
F.B.C.P. Edin., M.R.C.P. London. 
(Read December 21, 1891.) 
The object of this enquiry was to ascertain and compare the 
electrical resistances of various kinds of urine, both in states of 
health and of disease. 
The measurements were made by means of a Wheatstone’s bridge, 
with alternating currents, and a telephone according to Kohlrausch’s 
method. 
The fluids were held in a U-shaped electrolysis tube (a drawing of 
which accompanies this paper), of an internal diameter of about 
P55 centimetres, and containing a delicate thermometer. Two disc 
shaped platinum electrodes, each with a diameter of P4 c’m., were 
arranged so as just to rest upon the surfaces of the urine, with a 
very thin film of the fluid upon their upper surfaces. 
The electrodes were connected to the bridge by stout copper wires. 
An endeavour was made to maintain the temperature during the 
experiments at 65° Fahrenheit; and where this was not the case, 
a correction for temperature, from the result of some observations 
conducted for that purpose, has been made. 
The amount of urine used in each experiment was 21 c’c’s. 
I made an ordinary physical and chemical examination of each 
urine whose electrical resistance was tested, taking the specific 
gravity, reaction, colour, amount of urea, in certain cases also of the 
chlorides, and, if present, of sugar and of albumen. 
About three hundred experiments under these conditions have 
been made. 
With regard to the specific resistances, which together with the 
observed resistances are given in the Table, I found that the resist- 
ance of a saturated solution of zinc sulphate amounted under the 
above conditions {i.e.^ those under which all the urines were tested) to 
125 ohms. ; if we take, then, the specific resistance of such a solu- 
tion to be 21*5 ohms, as given in Lupton’s tables, we find that the 
numerical ratio of the specific to the measured resistance is 21*5/125 
