314 On Electrotyping Operations of the U. S. Coast Survey. 
To determine the most advantageous working temperature, 
end the resulting gain of effect, a voltameter battery was con- 
nected to a pair of electrodes, in the solution formerly described 
as being generally recommended. Each electrode had five square 
inches of face, and was coated on the back to prevent radiation. 
They were placed one inch apart, and had thin plates of wood 
und against their edges, to prevent any lateral spread of the 
current in passing between them. ‘he following was then ob- 
tained : 
Battery plates in contact gave 300 cubic inches gas per hour. 
Electrodes in contact . 216 do. do. Oo, 
Current through electrolyte, at 58°, gave 16 cubic in. gas per h. 23°15 
do. do. 60° do. 20 do. do. 
18:15 
do. do. 300° «do. 27. «do. do. 13°00 
do. do. 196*..; do. 3%. _.do. do. 8:96 
The last column of figures shows the value of the resistance 
of the solution, as compared with R of the formula. This ¢ 
umn was obtained by first uniting the battery plates, and after- 
wards the electrodes. 
From the above table it appears that heat may be made to di- 
minish the resistance in the decomposition cell in the proportion 
of 2-58 to 1; and the whole resistance by 2:25. Andas nr 
se 
R-++r ; therefore, by heating the electrolyte, we may with a sin- 
gle electrical equivalent make a plate as rapidly as by working at 
atmospheric temperatures with two batteries in consecutive order, 
with double surfaces, (four times the battery and twice the ex- 
se. 
But as Smee’s laws require that, in forming a plate, certain 
mutual conditions of apparatus be maintained, it follows that 
alterations in one element or condition must be attended by co 
responding changes in the others. Hence, if the temperature 
the electrolyte be raised to a certain point, and the apparatus cor 
respondingly adjusted, it is evident that, to aVoid incessant ad- 
justment, the original temperature must be maintained. 
Thus, to avail ourselves of the advantages experimentally 
found from heating the solutions, an apparatus for steadily main 
taining a high temperature in the electrolyte through several sue 
cessive days becomes indispensable. nr gre 
__ As the electrotype operations are not suspended at night, 138 
important that the heating apparatus should perform its office for 
at least twelve hours without supervision or replenishing 1S fuel 
and its action should be sensibly uniform, during all 
between successive replenishings. 
