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very cheap compared with the latter: a plate of platinized or 
gilded lead, one foot square, may be made for a shilling, but 
a platina plate of the same size will cost nearly three pounds ; 
secondly, the expense of working the former for any time is 
much less than the expense of working the latter for the same 
time ; thirdly, the nitre leaden battery does not emit fumes of 
nitrous gas. 
‘*¢ The leaden battery, when charged with nitro-sulphuric 
acid, appears not to exhaust the nitric acid so rapidly as the 
platina battery ; probably, a good deal of the hydrogen, which 
would otherwise unite with the oxygen of the nitric acid, is 
dissipated by the gold or platina powder on the surface of the 
lead. 
‘The advantage of the platinized or gilded leaden battery 
over Smee’s battery, is, that platinized or gilded lead costs far 
less than platinized silver. A plate of the former, six inches 
square, will not cost more than three-pence, whilst a plate of 
the latter of the same size, will cost about three shillings. 
‘* I shall now mention a few more experiments which I have 
made with the leaden and platina batteries. I compared their 
power in magnetizing our large electro-magnet, and in pro- 
ducing heat. ‘The magnetic power and heat produced by the 
platina, excited by concentrated nitric and sulphuric acid, was 
equal to that produced by the platinized lead excited by a 
mixture of nitre and sulphuric acid diluted with an equal bulk 
of water. Lach of the batteries fused the thinner of the two 
wires which I enclose. In each battery there was but a sin- 
gle voltaic circle. ‘The platina and leaden plates contained 
each about ten square inches; they were about five inches 
long and two broad. Neither of these batteries was able to 
_ fuse the thick wire; but when about a tea-spoonful of nitric 
acid was poured. into the cell containing the leaden plate, and 
the current sent through the thick wire, it was fused. The 
platina battery only raised the thick wire to a white heat. 
Hence, | infer that platinized lead, excited by a mixture of 
