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On Electrotyping Operations of the U. S. Coast Survey. 317 
ing vat is shown at V, and that of the horizontal vat at H. Sis 
alarge tub for washing plates. The tub C contains the solution 
of chlorid of iron. Q is the quicksilver tub, and W, W, are 
fresh water tubs. F is the furnace, and d, d, ¢, c, are heating 
tubes connecting with the vat H. T' isa flat iron table. 
Fig. 2 exhibits a cell and its included plates, with their mode 
of suspension. 
Fig. 3 represents the suspending frame of wood and the at- 
tached plate, P, prepared for immersion in the vertical vat. 
Fig. 4 shows the vertical vat and the plates suspended in ity 
Pig. 5 represents the adjustable plate-supporting frame used in 
the horizontal vat. 
Fig. 6 exhibits the interior arrangement of the horizontal vat, 
a blank plate and an engraved original being in position; also the 
Naches a heat of 180°, In principle this furnace is similar to a 
bath-heater. A tubular helix of lead is coiled within it like the 
worm of a still, and the terminating branches c and d lead to the 
horizontal vat, the branch ¢ uniting the top of the vat just below . 
8¢ shows it to be plane. It is then weighed aud fixed in the 
Vettical plate frame ee two copper hooks. The engraved plate 
'S then Similarly fixed in a similar frame, when both are placed 
a vertical vat and connected with the battery. 
_.& process does not go on well when the plates are vertical, 
bat it is Necessary to start the castings in this position to preven 
dust, motes, or specks of impurities, from settling on the face. 
rd € rolled plate dissolves, its impurities rapidly render the so- 
lution muddy, and endanger the face of the forming plate. For 
rommon electroty pes dust or mote specks are not detrimental ; 
~ the coast survey copper plates being not inferior in fineness 
lines to fine steel plates, the effect of impurities settling on the 
of their copies is to give the impressions a clouded appear- 
