of Edinburgh, Session 1874-75. 587 
We must therefore, it seems, be careful lest in correcting Ylacq 
by help of Prony’s calculations, we do not put him wrong where 
he is right. 
Postscript by M. Lefort . 
Les erreurs signalees sur le 10 rae chiffre decimal pour les logar- 
ithmes des nombres 24580, 26188, 26699 et 29163 sont moindres 
qu’une unite du 12 me ordre decimal. Or M. Lefort, dans son article 
sur les tables du Cadastre a prevenu que “ le 12 me chiffre decimal 
pent etre accidentellement en erreur de pres d’une unite,” page 26. 
Monday, 21 st June 1875. 
The Hon. LORD NEAYES, Vice-President, in the Chair. 
The following Communications were read : — 
1. Note on Electric Resistance of Solutions. By William 
Durham and P. R. Scott Lang, M.A. 
This note contains the results of experiments we have made on 
the electric resistance of solutions by a method brought under the 
notice of this Society by Messrs Ewing and M‘Gfregor, and de- 
scribed in their paper printed in the Transactions, vol. 27, page 
51. Our results, so far as they have gone, are as follows : — 
1. Resistance of solutions of sodium-chloride, and potassium- 
chloride, varying in strength from *002 grains to 4 and 5 grains to 
25 cubic inches of water. In these weak solutions the polarization 
was very little and easily got rid of, and the results satisfactory. 
On plotting these out in the usual manner, we found the curves 
described to be hyperbolas, as shown in the diagram, where the 
ordinates represent the strengths of the solutions and the abscissae 
the resistances. Becquerel, in his experiments on this subject, 
found the hyperbolas to be rectangular for the solutions he used, 
while Ewing and M‘Gregor found theirs not to be rectangular. 
We find some of our curves to be rectangular and others not. 
Thus we have — 
4 G 
vol. vnr. 
KC1 — not rectangular. 
