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VIII. Intelligence and Miscellaneous Articles. 
NOTE ON THE QUESTION—IS THERE ANY ADVANTAGE, IN CHE- 
MICAL DECOMPOSITIONS, IN INTRODUCING AN INDUCTION 
APPARATUS OF ONE WIRE IN THE CIRCUIT OF A VOLTAIC PILE ? 
BY C. DESPRETZ. 
[ a battery with one or two liquids in which the amalgamated zine 
is scarcely, if at all, attacked by dilute sulphuric acid, when the 
current is not established, the loss of weight of the zine corresponds 
with the oxygen of the water decomposed in the voltameter. This 
result shows that the pile is the most perfect of machines, when its 
force is measured by the decomposition of water ; for in this case the 
effective work is equal to the motive work within a hundredth, or 
sometimes a two-hundredth part. The pile is supposed to be com- 
pletely isolated, and the amalgamated zine not sensibly attacked by 
the dilute sulphuric acid. 
An experiment of M. De la Rive has shown that a pile which de- 
composes water very weakly, acquires the power of decomposing it 
in a very marked manner, if an induction apparatus be introduced 
into the circuit. M. De la Rive has given the name of voltaic con- 
denser to the induction apparatus of one wire which he employed. 
It has lately been asserted, that by an arrangement analogous to 
that of M. De la Rive, there is an actual economy in the consump- 
tion of zinc. Such an opinion can only he founded upon exact 
experiments. If the quantity of zinc consumed were less than that 
corresponding with the oxygen of the water decomposed, the union 
of a pile and an induction apparatus would form a more than perfect 
machine. Its useful effect would exceed the motive work, which would 
be a singular result. To settle this question, the only course is to 
weigh the amalgamated zinc before and after the experiment, and to 
compare the loss of the metal with the weight of oxygen and hydro- 
gen of the water decomposed in the voltameter. 
To make the necessary comparison, eight Bunsen’s elements were 
arranged in two sets of four elements. This arrangement is equivalent 
to two elements in tension, of four times the dimension. In the cir- 
cuit was placed a small induction apparatus with a single wire. 
When half a litre of gas (oxygen and hydrogen) was evolved in the 
voltameter, the loss of the zinc was 1°578 grm., on the average of five 
nearly concordant experiments. The average duration was an hour 
and two minutes. 
1°578 grm. of z:uc corresponds with a quantity of water represented 
by a voluine equal to 0°8131 litre of dry oxygen and hydrogen at 
32° F. and a pressure of 0'76 metre. The experiment only furnished 
0°500 litre of moist oxygen and hydrogen gas at a temperature of 
60°75 F., and a pressure of 0°7435 metre. In a dry state, at 32° 
F. and the pressure of 0°76 metre, the 0°500 litre is reduced to 
0°4531 litre. ‘Thus the induction apparatus causes a loss of 0°36 
litre, or four-ninths of the internal work, or four-fifths of the actual 
work obtained; in other words, nearly half the zinc is not repre- 
sented by the water decomposed in the yoltameter. If time were 
