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the use of a membranous partition, and two different liquids, 
to separate the respective metals ; but added, that the form 
this philosopher adopted was imperfect, in consequence of 
the difficulty of affixing the membranous portion staunchly 
to the sides of the square glass box which contained the 
two different fluids. 
The author, after referring to the sustaining battery of 
Professor Daniel and to the modification of that appara- 
tus adopted by Mr. Mullins, exhibited to the Academy a 
battery which he had devised to remedy a defect affecting 
all previous combinations, and in which each surface of the 
hollow zine cylinder had, as first recommended by Mr. 
Wollaston, a surface of copper opposed to it. An account 
was also given of several experiments which shewed the 
advantage of his form in calorific and electro-magnetic ex- 
periments. : 
Mr. Clarke’s improvement consists in attaching a ring of 
zinc by zinc rivets to the top part of the outside of the hollow 
cylinder of zinc used in the arrangement of Mr. Mullins, 
and drawing a bladder over this cylinder, to which it is 
secured by a cord to the ring ; and in replacing the earthen- 
ware jar by a copper cylinder, which is furnished with a 
mercury cup, as are also the zinc cylinder and the central 
copper. The central copper and the outer copper case are 
connected by a wire dipping into the cups. A solution of 
sulphate of copper is poured, as well into the outer case of 
copper, as into the bladder surrounding the central copper, 
and muriate of ammonia into the bladder enlosing the zinc. 
The author concluded by detailing some experiments, 
tending to shew that, (contrary to the opinions of M. Mari- 
anini and Mr. Mullins,) the maximum effect is obtained when 
the surface of the zinc element is equal, or nearly so, to that 
of the copper. 
ReEsotvep, on the recommendation of the Council,—That 
Q 
