IMPROVEMENTS IN COATING METALLIC SURFACES
Year: 1859

page_text: LETTERS PATENT to Alexander McDougall, of Manchester, in the County
of Lancaster, Chemist, for the Invention of "IMPROVEMENTS IN COATING
METALLIC SURFACES."
Sealed the 13th October 1859, and dated the 14th April 1859.
PROVISIONAL SPECIFICATION left by the said Alexander M°Dougall
at the Office of the Commissioners of Patents, with his Petition, on
the 14th April 1859.
I, ALEXANDER MCDOUGALL, of Manchester, in the County of Lancaster,
Chemist, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN COATING METALLIC SURFACES," to be as follows:-
My Invention consists in covering metallic surfaces with a preparation of
asphalte, pitch, or other bituminous substance mixed with sulphur. I take
asphalte or pitch and melt it in a suitable vessel, I then add sulphur dissolved
in oil of turpentine or other convenient solvent, and agitate until the materials.
are well mixed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander McDougall in the Great Seal Patent Office ou
the 14th October 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MCDOUGALL, of Manchester, in the County of Lancaster, Chemist, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of April, in the year of our
Lord One thousand eight hundred and fifty-nine, in the twenty-second year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Alexander McDougall, Her special license that I, the said
Alexander McDougall, my executors, administrators, and assigns, or such
others as I, the said Alexander McDougall, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time
and at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an Inven-
tion for "IMPROVEMENTS IN COATING METALLIC SURFACES," upon the condition
(amongst others) that I, the said Alexander McDougall, by an instrument in
writing under my hand and seal, should particularly describe and ascertain
the nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Alexander McDougall, do hereby
declare the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement, that is to say :-
My Invention of improvements in coating metallic surfaces relates more
particularly to a method of covering the surfaces of metallic pipes with a
preparation of asphalte, pitch, or other bituminous substance mixed with
sulphur, but the Invention may also be applied for coating other metallic
surfaces.
In carrying out my Invention, I take one part by weight of sulphur, and
dissolve it in two parts by weight of the heavy oil of tar or other convenient
solvent of sulphur, such as spirits of turpentine or rosin oil. In this solution
of sulphur, by the aid of heat, I dissolve five parts by weight of pitch or
asphaltum, and to this mixture I add a quantity of bees'-wax, the most suitable

page_text: proportion of which I have generally found to be five parts of bees'-wax to one
hundred parts of the bituminous mixture above mentioned. The above pro-
portions I have found to answer the purpose, but they may be varied as the
coating is desired to be of greater or less thickness, or, as in the case of sheet
lead, where a higher degree of elasticity is desired in the coating, in which
case I increase the proportion of bees'-wax.
The method in which I apply this mixture to the coating of metallic
surfaces is generally by the simple immersion of the metal to be coated in a
bath of the mixture. I prefer to have the mixture heated above the boiling
point of water, and the metal heated to about 400° Fahrenheit, although the
precise degree of heat is not essential.
In the application of my Invention to coating the interior of lead pipes
which it is not desired to coat on the exterior surface, I prefer to apply the
material during the operation of making the pipes, when such pipes are made
by the use of hydraulic pressure applied to the semi-molten metal, in the well
known manner.
When the pipe to be coated bas, by the application of the
hydraulic pressure, been forced through the die, and has risen a sufficient
height above the core, I pour into the pipe a quantity of the above-mentioned
bituminious mixture in a melted state. The quantity of the melted bituminious
mixture thus poured into the pipe must be sufficient to coat the interior
surface of the whole length of pipe intended to be made. The quantity
required of the bituminious mixture will of course vary with the character and
length of the pipe to be made. The manufacture of the pipe is then continued
by means of pressure as usual. In order to coat wrought or cast iron pipes
they should be first heated, and then either immersed in the melted bituminious
mixture, or the latter may be poured into the pipes so as to completely coat
their internal surfaces.
The coating of telegraph wires and other metallic surfaces is also effected
by passing the heated metal through a bath of the melted bituminious pre-
paration as will be well understood.
.
Having now described my Invention of improvements in coating metallic
surfaces, and having explained the manner of carrying the saine into effect, I
would here observe that the products of the distillation of coal tar have been
already applied to coat cast-iron pipes; I do not therefore claim, under the
present Patent the use of such materials for such purposes, except when used
in the manner, and in combination with the materials above named, or their
equivalents.
The peculiar feature of novelty in the above-described improvements, and
which I desire to claim as of my Invention, is the employment of sulphur and

page_text: bees'-wax in the preparation of the mixture to be used for the coating of cast-
iron pipes.
I claim also the application of the products of the distillation of coal tar, or
asphaltum derived from any other source, with or without the addition of
sulphur and bees'-wax, as above described, for the coating of sheet lead or
leaden pipes, or other metallic surfaces.
I claim the coating of telegraph and other wires with the above mixture of
the products of coal tar or natural asphaltum, in combination with sulphur
and bees'-wax, or either of them.
In witness whereof, I, the said Alexander McDougall, have hereunto set 1
my hand and seal, this Fourteenth day of October, in the year of our
Lord One thousand eight hundred and fifty-nine.
Witness,
J. W. MOFFatt,
66, Chancery Lane.
A. MCDOUGALL.
(L.S.)