124 
MR. DANIELL ON VOLTAIC COMBINATIONS. 
inch in the first five minutes: so that the superiority of the former, under these cir- 
cumstances, was even greater than before. 
I will only add, that 1 have kept six inches of platinum wire, -^-g-th of an inch dia- 
meter, permanently red hot for a considerable length of time when the battery was 
merely connected in single series, and that the spark between charcoal-points is re- 
markably beautiful ; and shall reserve for a future communication, if you will permit 
it, some observations upon the different modes of combining the plates, for which 
it affords great facilities, and the different important applications to which, from the 
invariableness of its action, it is applicable. 
My principal object in these researches has been the attainment of this constancy; 
but, in addition, this new combination will be found, I think, to possess advantages 
which will secure to it a more general application than I at first contemplated. 
First, the abolition of all local action by the facility of applying amalgamated zinc: 
Second, the trifling expense of replacing, the zinc rods when worn out (for they 
are easily cast and fitted in the laboratory) ; and the total absence of any wear of the 
copper : 
Third, the non-necessity of employing nitric acid, and the substitution of the cheaper 
materials, sulphate of copper and oil of vitriol ; to which I may add, the absence of 
any annoying fumes : 
And, fourth, the facility and perfection with which all metallic communications 
may be made, and different combinations of the plates arranged. 
Hoping that I may not have wearied you by these details, 
I remain, dear Faraday, 
Your very faithful friend, 
King's College , 
23rd January, 1836 . 
J. F. Daniell. 
