90 Mr. Tribe on the Influence of Current Sfc. 
Table V. shows that the degree of accuracy did not mate- 
rially differ under the three varying conditions. The magnet 
therefore does not appreciably interfere with the measure- 
ments. The mean error of all three positions of the magnet is 
022 per cent., which is very low. 
In conclusion, I may mention that a smaller model of the 
galvanometer, intended for practical use, is now being made, 
which will contain all the recent improvements, viz. the fine- 
wire coil besides the solid ring, the tangent-scale, the secant- 
marks, the air-damping, and the compensating-magnet. The 
latter will be so arranged that the " constant " will be consi- 
derably increased as compared with that due to the earth's 
magnetism alone ; thus the needle should be much less 
influenced by outer disturbances than before. 
Woolwich, June 1883. 
XIV. The Influence of Current, Temperature, and Strength of 
Electrolyte on the Area of Electrification. By Alfred 
Tribe, F.Inst. C, Lecturer on Chemistry in Bulicich College. 
IN the study of the subject of this paper I have employed 
the " electro-chemical method " described by me in the 
Philosophical Magazine, 1881, xi. p. 446. It will be remem- 
bered that by this method images of the electrifications pro- 
duced on metallic plates are rendered evident to the eye, and 
also that I have almost invariably employed as analyzers plates 
of silver, and as the electrolyte a solution of copper sulphate. 
The areas of the electrifications were found by measuring the 
copper and peroxide of silver respectively deposited or formed 
on the analyzing plate, the copper giving the area of the 
— electrification, and the silver peroxide that of the + elec- 
trification. The sum of the two electrifications subtracted 
from the total area of the plate, it will be seen, gives the area 
of non-electrification, i. e. the intermedial space, or that part 
of the plate which separates the + and — , and where the 
electromotive force is incapable of initiating electro-chemical 
action. These measurements are of course only relative. 
The following conditions were common to the several 
experiments to be described: — an electrolytic cell 120 millim. 
broad, 128 deep and 305 long, filled to within 8 millim. with 
copper-sulphate solution ; copper electrodes of the same area 
as the ends of the cell ; a plate (analyzer) of fine silver, 
67 x 7 millim., weighing 0*75 gram, placed lengthwise mid- 
way between the electrodes, and between the surface of the 
liquid and the bottom of the cell. The time of each experi- 
ment was six minutes. The diagram shows the general 
