123 
The deflagrator of Dr. Hare was first described in 1821,* and as 
above mentioned consisted of eighty concentric coils of copper and 
zinc, each coil having its glass jar of acid; the coils being attached 
to a common beam which was raised and lowered by means of levers. 
Subsequently he adopted the form of flat, hollow, copper cascs into 
which the zinc plates were made to slide, being secured in their 
places and prevented from actual contact with the copper by 
grooved pieces of wood which receive the edges of the zinc and 
rest against the inside of the copper cases ; each zinc plate being 
connected to the next copper case by a metallic strip. These cases 
were supported in frames and well insulated from one another, these 
frames being movable and capable of being lowered into the troughs 
containing the acid, or being stationary, and the troughs raised in 
order to immerse the plates. ‘This construction was the one adopted 
in the deflagrator made by Dr. Hare for the laboratory of Yale Col- 
lege. In his last form of instrument, called the Cruikshank defla- 
grator, the copper and zinc plates, soldered together in pairs at their 
edges, were fixed in a box supported on pivots; so that by rotating it 
through go°, the acid surrounding the plates flowed into a second 
and similar box attached to the first and at right angles to it. By 
reversing the motion the acid flowed again upon the plates.+ 
‘‘ Both in producing ignition and combustion,’’ says Prof. Silliman, 
“‘the deflagrators far surpass any other form of galvanic instru- 
ments. Combustion is exceedingly vivid ; the metallic leaves van- 
ish in splendid coruscations ; a platinum wire several feet in length 
fixed between the poles while the metals are in the air becomes red 
and white hot, and melts the instant they are immersed ; the largest 
wire of this metal fixed in one pole and touched to charcoal in the 
other, melts like wax in a candle and is dissipated in brilliant scin- 
tillations; a watch-spring or a large steel knitting-needle fixed in 
the same manner and touched to the charcoal point burns com- 
pletely away with a torrent of light and sparks; a stream of mer- 
cury fiowing from a funnel is deflagrated with brilliant light, and 
an iron wire is fused and welded to another under water.’’ { It was 
with this instrument that Prof. Silliman, in 1821, observed for the 
first time the transfer of the carbon from the positive to the nega- 
tive pole, this carbon rapidly collecting on the negative side into a 
* Amer. Jour. Science and Arts, Vol, iii, p. 105, 1821. 
+ Amer. Jour. Science and Arts, Vol. vii, 347 (1824) ; Vol. xxxii, 285 (1837). 
t Elements of Chemistry, Vol. ii, p. 672, 1831. 
