Year: 1886

page_text: Date of Application, 14th Dec., 1886
Complete Left, 13th. Sept., 1887.
Complete Accepted, 14th Oct., 1887
I, Alfred JULIUS BOULT of 323 High Holborn in the County of Middlesex,
M.I.M.E. do hereby declare the nature of this invention to be as follows:―
The construction of electric accumulators in which the salts of lead are formed in
an electro-chemical way presents serious inconveniences which I remedy in the
following manner; 1. Formation of the salts of lead;
Instead of leaving the oxidising of the lead exclusively to the oxygen of the water 1
produce the oxidation by an acid solution with an addition of an oxidising acid or
salt, which produces by the passage of the current a soluble salt of lead which is con-
tinuously decomposed by the sulphuric acid and passes into the state of peroxide of
lead.
In employing ordinarily the alkaline nitrates I obtain with a bath composed of ;
10 Kilogrammes of water; 2 Kilogrammes of sulphuric acid and 1 Kilogramme of
nitrate of soda a formation of nitrate of lead transformed continuously into sulphate
and then into peroxide of lead. In a few hours without either discharge or back
current the positive lead strips will be covered by an adhering and crystalline coat of
peroxide of lead of a great electric capacity and which even may exceed milli-
mètre in thickness.
2. To increase and regulate the formation of the salts of lead, I find it indispensable
to introduce great volumes of air into the bath. This is done either by blowing the
air in or by lifting the pole plates out or by any other convenient means. The action
is doubled in this manner irrespective of the composition of the bath.
3. To give the coat of peroxide a greater adherence to the lead the strips are
covered with small cells of very small dimensions which are arranged in the thickness
of the lead but do not pierce it. The peroxide even at the expense of the lead fills
these cells in a few hours with a perfect adherence to the lead.

page_text: 4. The leaden strips submitted to an energetic formation elongate at least 10% of
their length it is therefore impossible to place them rigidly into a frame; to this end
I suspend these strips from rods to which they are soldered or otherwise suitably
connected. This rod is so bent that when placed across the accumulator vessel it will
be immersed in the bath as well as the strips. In this manner the elongation can take
place without difficulty towards the bottom of the vessel.
5. To prevent the lead strips piling up against each other so as to impede the free
circulation of the gases the strips are obliquely undulated so that when they touch each
other they are only in contact at a small number of points.
It is well understood that the composition of the bath as well as the percentage and
the nature of the salts and acids employed may be varied, without deviating from the
principle of the invention, this latter being the continuous formation of peroxide of
lead by continually forming a soluble salt which is immediately peroxidised.
Dated the 14th day of December 1886.
COMPLETE SPECIFICATION.
Improvements in or relating to Electric Accumulators.
A communication from PAUL JOSEPH RUDOLPH DUJARDIN, of Paris, in the
Republic of France.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
M.I.M.E. do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and by the
following statement :-
The construction of electric accumulators in which salts of lead are formed by
electro-chemical agency is attended with serious inconveniences which may be remedied
in the following manner :-
1. As regards the formation of the salts of lead :-
Instead of deriving the oxygen necessary to effect the oxidation of the lead entirely
from the water it is derived from an acid solution of an oxidising salt added to the
water such acid solution being capable by the passage through it of an electric current

page_text: of producing a soluble salt of lead which is immediately decomposed by the acid of
the bath into an insoluble salt assuming the state of peroxide of lead.
-
Thus by employing alkaline nitrates the bath may be composed as follows:-
10 kilogrammes of water.
2 kilogrammes of sulphuric acid.
1 kilogramme of alkaline nitrate (of soda ammonia potash or other suitable alkali).
By the passage of an electric current nitrate of lead is formed which by the acid of
the bath is converted in a continuous manner into sulphate of lead and afterwards into
peroxide of lead. In some hours, without discharging or reversing the current, the
positive plates become covered with an adherent layer of crystalline peroxide of lead
which may be over a millimetre thick, of a great electrical capacity.
2. In order to increase and regulate the formation of the salts of lead it has been
found that it is useful to introduce large volumes of air into the bath. This may be
effected either by forcing the air into the bath by raising and lowering the plates or
by other convenient means. The reaction is thus doubled whatever may be the com-
position of the bath.
3. In order to facilitate the adhesion of the peroxide upon the plates the latter are
constructed in a cellular manner as shown in figure 1, a representing the surface of
the plate and b an edge view thereof. The form of the cells c may be varied as well
as the size thereof those in the drawing being magnified to about four times the
original size.
It will be observed that in forming the cells the lead plate is not perforated in such
a manner as to afford a passage from one side to the other. In a few hours the
peroxide which is formed at the expense of the lead fills the small cells and adheres
strongly thereto.
4. To prevent the plates from coming into contact with each other in such manner
as to interfere with the free circulation of the acid and the gases they are corrugated
as shown in figure 2 the corrugations running obliquely across the plates the obliquity
of adjacent surfaces being in opposite directions. Thus the surfaces of the plates de
which are opposed to each other in figure 2 are shown opened out bookwise in figure 3
the oblique lines indicating the direction of the corrugation which in this position
of the plates are all in the same direction but if one plate be turned and laid with its
face downwards or towards the other then the corrugations will be in opposite
directions and will cross each other and will only be able to come into contact at points
separated by the width of the corrugations.
Instead of corrugating the plates projecting points f (see figure 1, b) may be
formed thereon which will prevent too close contact and leave a free passage for the
circulation of water and gas.
5. As the dilatation or expansion of the corrugated plates subject to an active
formation may amount to 10 per cent. of the length of the plates it is practically
impossible to pack them in a rigid frame. To allow for this dilatation the plates may
be suspended from a bent rod or bar g shown in elevation in figures 2 and 4 (the
latter figure representing vertical sections of a cell-at right angles to each other—)
so that the plates are free to expand towards the bottom of the cell H.
The plates may be soldered to the bar g and also at their bottom edges to a second
bar g¹ parallel to the bar g as shown in figures 2, 34 and 5.
It will be readily understood that the composition of the bath described in the first
part of the specification may be varied as to the quantity or proportions of the salts or
acids employed and also as to the particular salt or acid employed as others might be
used having the same properties of giving rise to the continuous formation of peroxide
of lead by the continuous formation of an insoluble salt of lead capable of being
immediately peroxidised.
Having now particularly described and ascertained the nature of this invention as
communicated to me by my foreign correspondent and in what manner the same is to
be performed I declare that what I claim is :-
1. In electric accumulators the method or process of causing a crystalline and

page_text: adherent deposit of peroxide of lead upon the plates by the employment of a bath
composed of sulphuric acid and of one or more oxidizing salts such as the alkaline
nitrates and capable of being decomposed by an electric current substantially as
described.
2. In electric accumulators the method or process of causing the formation of a
deposit of peroxide of lead upon the plates by the employment of a bath composed of
an acid such as sulphuric and an oxidizing salt such as nitrate of soda capable of
giving rise during the passage of an electric current to a soluble salt of lead ready to
be transformed by the decomposition of the acidulated water into peroxidized sulphate
of lead without discharge or reversal of current substantially as described.
3. In electric accumulators the method of accelerating the oxidation of the lead by
means of air either forced into the bath or otherwise brought into contact with the
plates substantially as described.
4. In electric accumulators the method of increasing the adherence of the salts of
lead to the plates consisting in forming small cells of any desired form therein without
penetrating entirely through the plate substantially as described.
5. In electric accumulators the method of preventing too close contact between the
plates consisting in corrugating the plates obliquely and disposing them in such
manner that the corrugations on surfaces opposed to each other cross or are inclined
in opposite directions substantially as described.
6. In electric accumulators the method of preventing too close contact between
the plates consisting in forming projections such as fat various points of the surface
of the said plates substantially as described and shown in figure 16 of the accom-
panying drawings.
7. In electric accumulators the method of fixing the plates to two supports such
as G G the one at the top the other at the bottom in such manner as to leave the
plates free to expand towards the bottom of the cell substantially as described and
illustrated in the accompanying drawings.
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