of the Galvamec Deflagrator, &c. 349 
Each plate of zinc is soldered to the next case of copper, 
on one side. ‘This may be understood from the diagram, 
- 3. It must be observed, that the copper cases are o- 
pen only atthe bottom and top. They are separated from 
each other by very thin veneers of wood. 
ig. 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 
described ; and those made on Cruickshank’s plan, or of 
the form used by Sir H. Davy, in the porcelain troughs. 
if 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 in the other. In this 
case the zinc plates are exposed only on one side. The 
surface on which the acid can act, is therefore the same 
as in a deflagrator of 50 pairs, in which each zine plate is 
assailable on both sides. It ought to be understood, that 
the box containing the 100 Cruickshank plates is open at 
bottom, and is of such dimensions as to occupy the place 
of a box, containing 50 pairs of the deflagrator, receiving 
ns acid in its interstices from below, in the same manner, 
y a partial revolution of the troug Bi Seqqoo. 
8 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 
the copper and zinc surfaces of the deflagrator pairs, rep- 
resented by fig. 2; and that the mode in which the acid is 
thrown off, or on, the whole series, does not differ, materi- 
ally from that described in the instance of fig. 1. 
On contrasting the deflagrating power of the seri 
50, represented at fig. 4, with Craickshank’s plates in the 
box, that of the latter was _s nates tera feeble, and 
even when compared with the Cruickshank trough, Hg. 
in igniting indeole: or carbon, the power of the deflagrator 
