= 
ais 
= | +" 
2. ings of the Ainerican Philosophical Society, 49 
* consists of four troughs, each’containing 100 pairs within a space of 
about 30 inches in Jength. The pairs, severally, are of the Cruickshank 
& pattern, and about 62 inches square, independently of the grooves, so as 
to expose about 42 inches of zinc surface. Every fifth plate is eineioae 
into its groove by a compound of rosin and suet. The plates, interme- 
diate between those thus cemented, are made to fit tightly into their 
groove in consequence of a slight obliquity in their sides, can be 
extracte the aid of forceps, so as to be cleansed, and, when expedi- 
ent, scraped. The cementing of each -fifth plate tends to prevent any 
injurious retrocession of the voltaic fluid ; and yet when the intermediate 
four plates are removed, an interstice is vacated sufficiently large. to allow 
the stationary metallic surfaces to be reached by a scraper. The plates 
strip of wood 13 inches wide and 2 inches deep, is bored by a centre bit, 
60 as to have eight vertical and cylindrical holes, which are all supplied 
with mercury. By means of ropes of copper wire, these holes,are made 
to communicate severally with the poles of each of the troughs, so that 
every one of these has its corresponding mercurial receptacle. Arches 
of twisted copper wire are provided of such various lengths, that the re- 
ceptacles may be connected in such manner as to cause the associated 
troughs to act either as one series of 400 pairs each of 42 inches of zinc 
surface ; as a series of 200 pairs each of 84 inches of zine surface ; or 
a$ a series of 100 pairs each of 168 inches of zinc surface. In the usual 
mode of constructing the voltaic apparatus, the diversities of power that 
appertain to an apparatus in which the ratio of the size of the pairs to 
their number varies, as above described, can be produced only by chan- 
ges in the arrangement, which are too inconvenient to be employed; but, 
according to the contrivance described, are attainable simply by shifting 
the connecting arches, so as to alter duly the mode in which the recep- 
tacles are connected with each other. 
By means of this apparatus, the deflagration of metals, the arched flame . 
between charcoal points, the fusion of platina by contact with the aqueous 
Solution of chloride of calcium, the welding of iron wire to a rod of the 
Same metal under water, were all accomplished with the most striking 
Success, 
In repeating Davy’s experiment, in which the arched flame between. 
charcoal points was subjected to the influence of a permanent magnet, 
the reaction between the voltaic and magnetic fluids was so violent, as to 
Ve productive of a noise like that of small bubbles of hydrogen inflamed 
mM escaping from the generating liquid. This last mentioned experiment 
Was performed by request of Prof. Henry, who manipulated in the per- 
Tmance of it. 2 
Ol. xz, No. 1—Oct.-Dec, 1840. 7 
Mo. Bot. Garden, 
{901. 
