Galvanically Coating Objects with Pure Nickel.
Year: 1889

page_text: Galvanically Coating Objects with Pure Nickel.
I, GERHARD KRÜSS, lecturer at the University of Munich, doctor of Philosophy, of
Munich, in the Empire of Germany, 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 :-
According to experiments, made by the inventor, metallic nickel, regardless of the
known teclinical impurities contained therein, for instance iron, copper, arsenic,
manganese, silicium etc., not a chemical element, but an alloy. This alloy contains
averagely about 98 per cent. of a metal, similar indeed in its properties to the substance
hitherto named "nickel," but finer in various respects, which metal I will designate
with "Ni," and about 2 per cent. of an element considerably differing from nickel in
its properties and in the nature of its compounds. This element shall for the present
be designated with "X."
Ni, free from X, that is to say, nickel in the new sense of the word, is produced
from common nickel, nickel salts, or direct from the solutions of the raw materials
obtained by concentration smelting, by proceeding according to the different nature
of these elements. It is impossible to separate pure Ni by one operation from the
said alloy of Ni and X, very rich in Ni, as the combinations of X, also if insoluble in
the residue of their precipitant, are soluble in Ni-salts, therefore, resist separation
from the latter. It is therefore necessary to repeat one of the hereafter mentioned
operations several times or, preferably several of these operations are succesively per-
formed to obtain pure nickel. Said operations are derived from the following peculiar
properties of the compounds of the element X.
The neutral chloride, which is colourless
1) when treated with concentrated alkali lyes or melted with caustic alkali is not
changed into a hydroxide insoluble in water, but any hydroxide produced is wholly or
partly converted into a combination of alkali soluble in water. The snow-wbite
hydroxide precipitated by means of common alkali lyes, for instance normal solution,
is however very little soluble in the latter, also with the addition of a large residue of
the precipitant

page_text: 2) is but incompletely precipitated in solution through oxalic acid at a low as well as
at a high temperature, more completely however through oxalate of ammonium even at a
low temperature after short standing. A very great residue of the latter precipitant
can return the precipitant into solution.
3) is not precipitated in solution through fixed alkali lyes or ammonia, oxalate of
ammonium or oxalic acid even at a high temperature, if the solution has been
previously acidified by the addition of organic acids, for instance acetic acid, citric
acid, pyrotartaric acid etc., whereas the soluble double oxalates of Ni are decomposed,
on heating their solution, by one of the said acids and deposit insoluble oxalate of
nickel. If the combinations of the element X are, in solution or otherwise, brought
in contact with a metal which is more electro-positive than Ni, for instance with zinc,
the compounds are not reduced even by short heating.
All these properties inherent on the pure X-compounds are to a different extent or
completely altered and concealed, if a solution contains besides X salts also combina..
tions of Ni. This is the case in the nickel salt solutions of former designation. The
white hydroxide of X, for instance, is not at all precipitated by ammonia, if, in a
nickel salt solution of former designation, more than 70 per cent. of the dissolved
substance consists of Ni salt.
If the nickel raw materials obtained by concentration smelting contain mixtures,
rich in X, of Ni and X or of their salts, or solutions rich in X, of commercial nickel
or commercial nickel salts, the neutral solutions, to separate the Ni from the X, are
mixed with ammoniacal oxalate of ammonium, till the precipitate produced is redis-
solved. Subsequently they are allowed to stand for some time, white, basic oxalate of X
being thereby precipitated, and some more ammoniacal oxalate of ammonium is added.
This addition is repeated until, after some longer standing, the quantity of the white
precipitate ceases to increase. The blue liquid above the precipitate having been
evaporated, its residue is thoroughly glowed and then mixed with such a quantity of
muriatic acid as is required for solution. The solution of chloride is subsequently
concentrated and while heating it, solid hydrate of soda, up to five times the weight of
the chloride, is incorporated therein, the doughy mass thereby produced being kept
melting for a short time. The molten mass when cooled is broken up and brought in
small pieces into ice-cold water, care being taken, if necessary by the addition of ice,
to prevent the temperature of the liquid from rising above 10° Centigrade. Thereby
the natrium compound of the oxide of X is dissolved, while rather pure hydroxide of
Ni remains undissolved. The alkaline liquid containing ✗ having been poured or
drawn off after some standing, the hydroxide of Ni is washed by decantation and dis-
solved in weak mineral acids or in acetic acid. This solution is mixed with such organic
acids as are also capable of preventing the aluminium from being precipitated through
alkalis, for instance with acetic acid, pyrotartaric acid or citric acid. On adding soda
lye to the liquid thus obtained, while heating, pure hydroxide of Ni, free from X, is
precipitated; or pure oxalate of Ni, free from X, can be produced in boiling beat by
precipitating the said solution of nickel, acidified with an organic acid, with soluble
oxalates, for instance oxalate of ammonium, all X being thus kept in solution, as by
the preceding operations the greater part of X has already been eliminated from the
commercial nickel or its salts.
In lieu of this however, also the solutions of commercial nickel, of its salts or of the
nickel raw materials obtained by concentration smelting, and the nickel compounds
produced by the above treatment may be decomposed into pure nickel (Ni) or its salts
and the element X or its compounds respectively by bringing the nickel compounds
or solutions referred to in contact with a metal which is more electro-positive than the
Ni-metal itself. Nickel salts are in this manner more easily reducible and, for instance
a solution of sulphate of nickel, chloride of nickel, or nitrate of nickel is soon almost
completely decoloured when warming it with zine dust or fine zinc chips, nickel metal
being precipitated and zinc brought in solution as sulphate. The compounds of X are
thus not reduced and remain in solution.
If the neutral or weak acid solutions of the nickel raw materials, obtained by con-
centration smelting, or like solutions of commercial nickel or nickel salts contain but

page_text: few X-compounds, pure nickel can be obtained from them by performing once or twice
one of the two last described operations.
The pure nickel obtained by the above described process is particularly adapted for
galvanically coating objects. While the nickel obtained by the processes already
known has a brownish yellowish hue, owing to the metal herebefore nanied X,
inherent thereto. the colour of pure nickel (Ni), if not perfectly free from a yellowish
shade, is decidedly more like silver and lighter, its application consequently preferable
to the galvanic nickeling heretofore in use. To this end, any of the known processes
may be applied hy using nickel salts free from X for producing the alkaline neutral or
acid nickel baths, and as nickel anodes such of nickel free from the element X, or
from its oxide.
Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed. I declare that what I
claim, is
1) The process for decomposing commercial nickel and its salts into pure nickel (Ni)
or into pure nickel salts and into an element, designated with "X" in the specifica-
tion, or its salts, that is to say the process for producing such metals (Ni and X) and
their compounds, substantially as described.
2) The application of nickel, free from the element designated with X in the
specification, or of the salts of such nickel for galvanically coating objects.
Dated this 25th day of January 1889.
GERHARD KRUSS.
By Huelser & Co.,
His Agents.