Hare on the Galvanic Deflagrator. 101 
trough is situated as when not subjected to the acid. In the 
representation of the lower trough, the galvanic series is 
omitted, in order that the interior may be better understood. 
The series belonging to this trough, may be observed be- 
low it, in three boxes, each containing 50 pairs, fig. 2. In 
placing these boxes in the trough, some space is left be- 
tween them and that side of the trough on which the acid 
enters, so that instead of flowing over them, it may run 
down outside, and rise up within them. 
The pairs of the series consist of copper cases, about 7 
inches long, by 3 inches wide, and half an inch thick; each 
containing a plate of zinc, equidistant from its sides, and 
prevented from touching it by grooved strips of wood. 
Each plate of zinc is soldered to the next case .of copper, 
on one side. ‘This may be understood from the diagram, 
fig 3. It must be observed, that the copper cases are open 
only at the bottom and top. . They are separated from 
each other by very thin veneers of wood. 
Fig. 4. represents a smaller trough, differing from the 
others only in length. This I made, with a view to some 
experiments on the comparative power of the galvanic pairs 
of the form of copper cases, with zinc plates, above describ- 
ed, and those made on Cruickshank’s plan, or of the form 
used by Sir H. Davy, in the porcelain troughs. 
Fig 5. represents a box, containing 100 Cruickshank 
plates, (each consisting of a plate of zinc, and copper, sol- 
dered face to face,) and slid into grooves, at a quarter of 
an inch distance from each other; all the copper surfaces 
being in one direction, and all the zinc surfaces in the oth- 
er. In this case the zinc plates are exposed only on one 
side. The sum of the surfaces on which the acid can act, 
is therefore the same as in a deflagrator of 50 pairs, in 
which each zinc plate is assailable on both sides. It ought to 
be understood, that the box containing the 100 Cruichshank 
plates is open at bottom, and is of such dimensions as to 
occupy the place of a box, containing 50 pairs of the de- 
flagrator, receiving the acid in its interstices from below, in 
the same manner, by a partial revolution of the trough, 
fig. 4. 
Fig. 6. represents a box, containing 200 Cruickshank 
plates. This differs from the common Cruickshank trough, 
only, in having the interstices as narrow as those between 
