378 Miscellaneous Intelligence. 
the copper disc with the other, and then lift this disc from the zinc. 
As soon as the separation is effected the gold leaf will strike the ball, 
usually if the one be not more than +3, of an inch apart from the 
other.” “That the phenomenon arises from the dissimilarity of the 
metals is easily shewn by repeating the experiment with a zine disc, 
in lieu of a disc of copper. ‘The separation of the homogeneous discs. 
will not be found to produce any contact betweenthe leaf and the ball.” 
** Itis probable that the sensibility of this instrument is dependant 
on that property of electricity which causes any surcharge of it 
which may be created in a conducting surface, to seek an exit at the 
most projecting termination or point connected with the surface,” 
this disposition being increased of course by the proximity of the ball. 
These effects are not to be expected in weather unfavourable to elec- 
tricity, but in favourable circumstances they have been produced by 
a smaller instrument, the discs being only two inches and a half in 
diameter. 
8. Hare’s V oltate Trough.—Dr. Hare states that, having had occasion 
to remark the surprising increase in the deflagrating power of a series 
of galvanic pairs, when, after due repose, they were simultaneously 
exposed to the acid, he was induced to devise means of accomplishing 
this object in various, ways, and that ultimately the following method 
occurred to him as the best: Two troughs are joined lengthwise edge 
to edge, so that when the sides of the one are vertical, those of the 
other are horizontal. Then by a partial revolution of the two troughs, 
thus united upon pivots which support them at the ends, any fluid 
which may be in one trough must flow into the other, and on revers- 
ing the motion, must flow back again. The galvanic series being placed 
in one of the troughs, the acid in the other, by a movement such as 
above described, the plates may all be instantaneously subjected to 
the acid, or relieved from it. 
The pivots are made of iron, coated with brass or copper, as less 
liable to oxidizement ; they are connected within with the galvanic. 
series, and move on pieces of shcet-copper, which are easily made 
the extremities of connecting pieces, and thus the whole can be ar- 
ranged in any way found convenient. 
9. Dobereiner’s Instantaneous Light Apparatus.—Since the very 
curious observation made by M. Doberciner of the power possessed 
by spongy platina of determining the combination of oxygen and hy- 
drogen at common temperature, that substance has been applied, 
among other uses, to the construction of an instantaneous light ap-= 
paratus; a jet of hydrogen is thrown on to a portion of the spongy 
platinum, and is by it inflamed. Various modes of presenting the 
plantinum to the hydrogen have been devised, but none surpass or 
even equal that originally adopted by M. Dobereiner. The extre- 
mity of a fine platina wire is to be rolled into a spiral form, and then 
