CERTAIN IMPROVEMENTS IN COATING OR COVERING METALS WITH TIN
Year: 1850

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALFRED
GUILLAUME ROSELEUR, of Paris, in the Republic of France, but now of
4, South Street, Finsbury, in the County of Middlesex, Chemist, send
greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-third day of
March (One thousand eight hundred and fifty), in the thirteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Alfred Guillaume Roseleur, my exors, adiñiors, and assigns, Her especial
license, full power, sole privilege and authority, that I, the said Alfred
Guillaume Roseleur, my exors, admors, and assigns, or such others as I, the
said Alfred Guillaume Roseleur, my exors, adiñors, or assigns, should at any time
agree with, and no others, from time to time and at all times during the term
of years therein expressed, should and lawfully might make, use, exercise, and
vend, within England, Wales, and the Town of Berwick-upon-Tweed, and in.
the Islands of Guernsey, Jersey, Alderney, Sark, and Man, and also in all Her
said Majesty's Colonies and Plantations abroad, my Invention of "CERTAIN
IMPROVEMENTS IN COATING OR COVERING METALS WITH TIN;" in which said Letters
Patent is contained a proviso, that I, the said Alfred Guillaume Roseleur,
should cause a particular description of the nature of my said Invention, and
in what manner the same is to be performed, by an instrument in writing
under my hand and scal, to be inrolled in Her said Majesty's High Court of

page_text: Chancery within six calendar months' next and immediately after the date of
the said in part recited Letters Patent, as in and by the same, reference being
thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Alfred Guillaume Roseleur, do hereby declare that the nature of my said
Invention, and in what manner the same is to be performed, are fully described
and ascertained in and by the following statement thereof, that is to say:-
My Invention consists of certain improved processes of applying tin on all
kinds of metals and their alloys, either by immersion alone or by immersion
with double affinity, and also by a galvanic current. I am well aware that
since the application of electricity to the decomposition of metallic salts
many patents have been obtained, and many trials have been made experi-
mentally to supersede the old process of coating or superposing metals upon
metals, but the only useful and commercial application which has really
resulted from these numerous. trials has been the galvanic reduction. of the
precious metals, or of those little liable to oxidation. Tin has scarcely attracted
the attention of chemists, though I must say that some have endeavoured to
make use of the well-known electro processes for coating with gold and silver
for the application of a film of tin on metals, but either on account of the
wrong mode of conducting the experiments, or that the dissolving agents
employed (such as the cyanides) were too expensive, or that the galvanic
reductions could only be obtained with too many difficulties or with too great
an outlay, it has resulted that no useful and commercial application of the
galvanic reduction of tin upon metals has ever been obtained; as I cannot call
satisfactory and useful the few results, which are defective in point of
appearance, and present no security against oxidation, I can therefore safely
assert, that, by the three improvements herein-after described, I am the first
who rendered commercially useful and profitable the application of tin on all
kinds of metals and alloys of metals.

page_text: salts of the same base, one ounce. A formation takes place by the escape of
part of the ammonia (when an alum of that base is employed) of a double
alum, having a stannic base, which, in the presence of iron, for instance, dis-
solves a small part of that metal, and replaces it by the tin which was in
solution, therefore a residuum of an alum of iron is left in the liquor after
the operation is over instead of an alum of tin. The seventeen and a half
ounces of alum employed will last a long while, for this reason, that I can add
the tin salt in small quantities by degrees as soon as the bath begins to lessen.
This bath, which is of little importance as a tinning process, acquires how-
ever considerable value when employed as a means of scouring and cleaning,
for it answers admirably for preparing castings of iron and other rough articles
to receive the coating of tin obtained by the different processes herein after
described. I think it right
I think it right to observe, that the improvement herein-before
stated is the first that has been discovered of a chemical composition capable
of depositing tin in a state of white adherent layers on a metal without the
presence of a galvanic current. This bath also whitens zinc and analogous
of the processes I employ, and the theory which I lay down in this Speci-
fication, will fully explain the reason for which I denominate double affinity the
mode of covering all metals with tin, zinc however excepted. I will premise,
before describing the operation by offering an explanation of the said theory.
In commerce, the direct tinning of iron has never been performed, except for
the manufacture of sheet tin and block tin. It is obtained by plunging the
metal, properly scoured and prepared on purpose, in a bath of molten tin.
The present part of my Invention has nothing whatever to do with that
process, my improvement consisting in the direct application of tin upon iron.
or any other ordinary metal by means of a suitable solution, and by giving
rise to a double affinity, herein-after described. I combine by my process
facility of execution with considerable economy. Its application is more
especially important for iron, cast iron, and steel, which it preserves from
oxidation, and to which it gives a whiteness nearly equal to the color of
silvered articles. By this process tin is applicable to all metallic surfaces-
even when only partially cleansed, which means that the bath herein-after
described combines with its property of depositing the. tin combined in it
that of dissolving the metallic oxides on the surface of the articles immersed,
in a word, it scours before tinning. The coating of tin thus deposited is

page_text: so uniform that it does not in any way change the surface of the article tinned,
were it rough or smooth it would be the same after the operation. I
can also obtain a fine dead color, similar to that produced by the galvanic
deposit of silver. This uniformity of coating, which might appear to be an
inconvenience when applied to an instrument made of an unworked metal,
which by the common tinning would have all its cavities filled, becomes very
precious for finished, carved, engraved, or moulded articles; and thus this kind
of tinning is perfectly applicable to all smiths' work, to engraved plates, which
it preserves from oxidation without altering their details; taps, pullies, castors,
fire-arms, and batteries may also advantageously receive the application of
this mode of tinning. The following is the method I find the most advan-
tageous for producing commercial results:-I digest in a hot state in seventeen
and a half pints of soft or common water ten and a half ounces of bitartrate
of potash or soda (tartaric acid, or acidulated tartriate of potash or soda,
cream of tartar). I pour into it an aqueous solution, consisting of three-
fourth of an ounce of protochloride or other salt of tin. The liquid first
turns milky, then entirely clears up. The bath is then, and especially after a
few moments of ebullition, quite fit to produce a good tin coating upon the
articles, which I immerse in it simultaneously with a few pieces of zinc: I
would observe, that the proportion of zinc must be very small relatively to
that of the articles to be tinned; without this precaution the tin would pre-
cipitate too quickly, and the bath be impaired in quality. The cream of tartar
employed will last almost indefinitely; it is merely necessary when the bath
does not contain sufficient tin to add a fresh quantity of any salt of this metal
to enable me to repeat the operation. I may add, for the information of
manufacturers, that I can without any inconvenience employ this bath to tin
several different metals at a time, such as copper, brass, steel, iron, cast iron,
lead, &c. &c. Although I have only described, one formula, I can, however,
make use of a vast number of other salts, which under similar circumstances
produce the same effect, as I have obtained it with the borates, sulphates, but
principally with the pyrophosphates of an earthy or an alkaline base, when
soluble. All those salts, in fact, answer the same purpose as cream of tartar,
for like that agent they form with tin double decomposable salts by the simul-
taneous presence of zinc and another metal; but in general their price is
higher, and that is the reason why I use bitartrate preferably.
I will now lay down the theory on which I found this mode of tinning,
which is principally applicable to the formula herein-before described. The
chloride of tin is decomposed by its contact with the tartrate of potash, and
there is formed a quantity of chloride of potassium corresponding to the

page_text: stannic chloride employed, and the result is a double tartrate of potassium
and oxyde of tin, a salt which is analogous to the emetic, which consists really
of a double tartrate of potassium and oxide of antimony.
The following formula represents the composition of the bath before being
put in action:-
It is easy to understand, by inspecting this formula, that the second part of
the tartrate of potash is decomposed at the same time as the protochloride of
tin. The arrow A shows the combination of the chlorine with potassium to form
the chloride of potassium, which is inert in this bath; the arrow B indicates
the combination of oxygen and tin, which uniting (as indicated by the line F
which joins the braces E and D) with the tartaric acid of the decomposed
tartar, forms the tartrate of oxyde of tin, and this lastly combines, as shewn by
the brace K, with the decomposed tartrate of potass to form the bitartrate of
potass and oxyde of tin, which is the efficient part, that is to say, the double
salt in which the tinning must be- performed. If I plunge into that solution
iron alone, or iron and tin together, as is done for the tinning of brass or iron
with copper or other metals, which by their contact form a voltaic couple,
nothing at all is produced; but if I plunge in together iron and zinc, or one of
the metals analogous to the latter, that is to say, a metal that may be sub-
stituted for tin of the nature of the emetic (which the latter, namely the tin,
formed with the cream of tartar), the tinning is immediately obtained, which
fact I explain in the following manner:-Zinc, like antimony and tin, can
form, though at a much higher degree of temperature than these two latter,
with cream of tartar, an emetic or a double tartrate, consequently if I introduce
it into an emetic of tin it will displace the latter from its combination, be sub-
stituted for it, and finally-will force it to deposit in its native state on the other
metals, for which it has more or less affinity. I was therefore warranted to
have herein-before stated that the tinning by my process is obtained by means
of double affinity, since by one affinity zine displaces the tin, whilst by means
of the second affinity the tin is made to deposit in the form of white and
adhering layers on the iron or other metals which happen to be in the solution
at the same time.

page_text: Electro Tinning. This part of my Invention has for object electro tinning.
I am well aware that many chemists, on account of the difficulties to be sur-
mounted and the inefficiency of the mode employed, have considered electro
tinning as disadvantageous. Most of them have employed cyanide of potassium
or a solution of sulphate of tin with a single battery; but, beside the exorbitant
price of the first of those two agents, no advantage can practically accrue from
such proceedings, which only produce a crystalline or spongy tin and necessitate
the fusing of it. I have had, therefore, to discover, firstly, a solvent capable of
holding in a state of solution a considerable quantity of tin; secondly, to
deposit, by means of a feeble galvanic current, the tin on the metal, with which
I was to place it in contact in the form of white and adhering layers, having
the durability, and at a price duly proportionate with the cheapness of tin
itself. I have overcome all these difficulties by the following process, which
has answered my most sanguine expectations :-I prepare a solution composed
of seventeen and a half ounces of water deprived of alkine salts, eleven pounds
of pyrophosphate of potass or soda, and four pounds seven ounces of proto-
chloride of melted tin. I operate under the influence of the battery, either in
the cold or hot state, though I prefer the latter mode. The positive pole of
the battery is represented by an anode of tin, which is immersed in the bath,
and which ought not to touch the articles to be tinned. These last are hung
to the negative pole of the battery. This bath may likewise act with the
contact of zinc only, but then it is included in the second mode of operation,
herein-before described. I am enabled by this last process to tin admirably
well cast iron, zinc, copper, and any other metal, and I can regulate the
thickness of the layer of tin to be deposited, as I act under the influence
of an electric current. It is, I think, superfluous to lay down here all the
applications of my process, the usefulness of it will be easily demonstrated
by its commercial extent. I wish it to be observed that the metals and
their alloys before being tinned by the processes herein-before stated must
be cleansed as usual by means of hydrochloride, sulphuric, or azotic acid.
And having now described the nature of my Invention, and the manner
of carrying the same into effect, I wish it to be understood that what I
claim as my Invention, and intended to be protected by the said Letters
Patent, is,
Firstly, the coating of metals and alloys of metals by the direct super-
position of tin in a suitable stannic solution without double affinity or voltaic

page_text: current, and the application of the said process to scouring of metals and alloy
of metals intended to receive a future coating, as herein-before described.
Secondly, the application of the process of double affinity for tinning metals
and alloys of metals by means of the simultaneous presence of any metal, and
of zinc, or any analogous metal, in a solution purposely prepared as herein-
before described.
Thirdly, the application of the voltaic current to the decomposition of
suitable tin solutions for coating metals and alloys of metals, as herein-before
described.
In witness whereof, I, the said Alfred Guillaume Roseleur, have hereunto
set my hand and seal, this Twentieth day of September, in the year of
our Lord One thousand eight hundred and fifty.
This is the Specification marked A, referred to in the affidavit of William
Armand Gilbee, sworn this 23rd day of September 1850, before me,
HENRY MOWBRAY.
WLLIAM ARMAND GILBEE, of 4, South Street, Finsbury, in the County of
Middlesex, Gentleman, maketh oath and saith, that he is acquainted with the
manner and character of the handwriting of Thomas Pickford, Her Britannic
Majesty's Consul at Paris, in the Republic of France; and this deponent
further saith, that the signature "Thomas Pickford," set, subscribed, or written
in the margin of the Specification hereunto annexed, marked A, and dated the
Twentieth day of Séptember instant, and purporting to be executed by Alfred
Guillaume Roseleur, of Paris, whereby it is stated that the Specification was
acknowledged by him, the said Alfred Guillaume Roseleur, before the said
Thomas Pickford, on the said 20th day of September, at Paris, aforesaid, is of
the proper handwriting of the said Thomas Pickford.
W A GILDER

page_text: AND BE IT REMEMBERED, that on the oath of William Armand
Gilbee, the Specification aforesaid was enrolled, word for word, as above
written. And also the Specification aforesaid was stamped according to the
tenor of the Statute made for that purpose.
Enrolled the Twenty-third day of September, in the year of our Lord