: a7 s ‘ * ‘ 
158 _ Blectrography. : % 
3. A connection must also be established between the two fluids) * 
by means of a metallic strap or wire; to the end of this strap 
which is in the metallic salt, must be soldered the object to be 
copied, which must also be a metal or at least have a metallic sum — 
‘face ; to the other end of this metallic connection, which is in the 
acidulated water, a piece of zinc must be attached by soldering. — 
The accompanying figure taken from Mr. Fig. 1. 
Spencer’s pamphlet, will render the forego- 
ing conditions of the experiment quite plain. 
A, is a glass vessel, (a common drinking tum- 
bler answers very well;) B, is a straight tube 
of glass, in this case an argand lamp chim- 
ney, having the lower end closed by a dia- 
phragm of plaster, brown paper, or animal 
membrane; C, the object to be copied; H, 
a piece of zinc; F, the copper connecting 
wire siete C and E; D, acover of any 
convenient material, (a cork or piece of wood,) ; 
fitting A, and provided with two holes, one in the center for hold- 
ing the glass B in its place and another to permit the wire F to 
pass. The apparatus being thus arranged, pour into A, a satura 
ted solution of sulphate of copper ed to 100° or 120°F., 
and into B, a warm weak acid water to the same level as the s0- 
lution in the outer vessel.* 
A more simple form of apparatus, Fig. 2. 
and one which we have used with good = 
success, is shown in the following fig- 
ure ; we describe it because we believe 
it is much better adapted to the means 
of the inexperienced experimenter than 
the foregoing, and its manipulation is 
also much simpler. 
A, is an earthen ware pot of any requi- 
site capacity ; B, 6, the porous division, 
which may be made by casting plaster 
of Paris across from side to side, and 
* 
* 
tes are vertical, 
* Mr. $ bjects to th 
r. Spencer objects to the use of an apparatus where the p — no difficulty 
because the deposition is of unequal thickness; but we have foun 
if the solution is kept saturated. , 
