a 
a 
On Electrotyping Operations of the U. S. Coast Survey. 315 
_ Such an apparatus I have devised, and is now in use. A peck 
of charcoal furnishes fuel for twelve hours, and maintains 100 
lons of copper solutions steadily, at any required point be- 
tween 100° and 200°. 
_ With the above arrangement in use, I have made a large re- 
verse or alto, and returned the original to the engraving depart- 
ment in 55 hours from its being placed in my hands. This time 
eevee trimming the edges and the preparations to prevent ad- 
on. 
Again recurring to Ohm’s formula, the relative value of R i 
oe 1 . 
rwas once more experimentally found. This gave R:r:: 
rO= 71 = 920, a great improvement as compared with the 
. : , 
first determination of R:r::1: 19, or Qrris Having 
how made r so small compared with R, the size of the battery can 
be profitably increased until the result is about 0:24. Moreover, 
using a double arrangement of cells with double surfaces, for a 
doub| (eran ‘40, As the rela- 
ible effect, we now have 2 i 0 s 
live resistance of the electrolyte becomes now still smaller, we may 
yet more increase the battery surface until the result is nearly 0°5. 
he electrotype has now ceased to be a mere experiment, un- 
certain, expensive, and slow. I have lately formed plates of 
most excellent quality, at the rate of three pounds to the square 
foot, in 24 hours. This rate will require but two days to form 
ste of our largest plates, having ten square feet surface, and one- 
th of an inch thick. 
in the electrolytic solution. 
besited metal is governed solely 
Wantity of the electricity passing throug 
‘mount of metal the solution contains. 
—The quality of the de- 
the relations between the 
h any solution and the 
The usual supposition 
-S that the acid of the salt goes to one electrode and the me 
ite other, but it is now ascertained that no such spine, ees 
®s place ; for, while the acid is carried to the positive elec “a . 
the metal is not carried to the negative electrode. Hence, how- 
“et strong the solution on commenci 
and the electrode is soon sur- 
With a weak solution. This state of things must be 
ih, ized in adjusting our battery arrangements. Electrotypists 
“ot aware of this fact find themselves much perplexed by 
