IMPROVEMENTS IN THE MANUFACTURE OF SODA AND SULPHURIC ACID
Year: 1861

page_text: PROVISIONAL SPECIFICATION left by Emory McClintock at the Office of
the Commissioners of Patents, with his Petition, on the 28th October
1861.
I, EMORY MCCLINTOCK, of No. 200, Mulberry Street, New York, United
States of America, now staying at No. 100, Fleet Street, in the City of
London, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN THE MANUFACTURE OF SODA AND SULPHURIC ACID," to be as follows:-
These improvements consist partially in the substitution of copper or any
one of its compounds reducible by coal for carbonate of lime, as used in the
ordinary soda manufacture, with the exception of the proportions taken, the
process is in all respects similar to the said ordinary soda manufacture. The
furnace used, the mode of charging it, the phenomena of fluxing, the regulation
of the heat according to these phenomena, the withdrawing the mass from the
furnace, the cooling, the lixiviation of the "rough soda," and the evaporation of
the waters of lixiviation are all the same as in the usual and well-known pro-
cess. The residue of lixiviation is a sulphuret of copper instead of the ordi-
nary oxysulphuret of calcium. Instead of copper may be used suboxide or
oxide of copper, or carbonate of copper, or any mixture of these. The propor-
tions I use are such as to have two chemical equivalents of copper to each
equivalent of sulphate of soda, that is, by weight about six and one-half parts
of metallic copper, or eight parts of oxide of copper to every seven parts of
sulphate. If other reducible compounds of copper be used, the amount taken

page_text: must be determined in a similar manner. To complete the mixture, I add to
seven parts of sulphate of soda and eight parts of oxide of copper, as above,
three to three and one-half parts of coal slack, or an equivalent quantity of
any other carbonaceous material. If suboxide or metallic copper be used, the
amount of coal must be reduced about twenty or forty per cent. respectively.
The materials having been powdered are mixed and fluxed as usual, as herein-
before stated.
My improvements consist further in the reconversion of the residual sul-
phuret of copper obtained as herein-before stated, into oxide of copper, or
metallic copper, or suboxide, &c., as the case may be, at the same time saving
the sulphur for the manufacture of sulphuric acid or sulphate of soda. I effect
this by ordinary chemical means as follows:-I roast the sulphuret in an ordi-
nary muffle oven, either quickly and at a high temperature, or slowly and at a
low temperature. In the first case it is converted into oxide of copper evolving
sulphurous acid gas, which I lead into leaden chambers for the manufacture of
sulphuric acid, as in the ordinary manufacture. Instead of roasting completely,
I can also arrest the process when it is but half or three-quarters completed,
exclude the air, and raise the heat briskly, obtaining thus respectively metallic
copper or suboxide of copper, and evolving sulphurous acid gas, as before.
In the second case, the sulphuret is converted into a mixture of sulphate
and oxide of copper. This I either decompose by heating briskly, driving off
a mixture of 'sulphurous and sulphuric acids, which I lead into the leaden
chambers, as before, and leaving oxide of copper; or, I treat it with boiling
water to dissolve out the sulphate.
In the former case, if the roasting be but about four-fifths complete, only
sulphurous acid will be evolved; if but one-half or two-thirds complete before
heating briskly, the oxide 'obtained 'will contain a large proportion of suboxide
and of metallic copper.
I find that the admission of steam always assists the evolution of sulphurous
acid. In the latter case, I add to 'the 'solution of sulphate of copper an equi-
valent quantity of common salt, and evaporate till the sulphate of soda which
is formed is all deposited. This I decompose, as herein-before stated. The
solution contains chloride of copper, to which I add an equivalent amount of
slaked lime, or carbonate of lime, or metallic iron, obtaining a précipitate com-
posed respectively of oxide or carbonate of copper, or of metallic copper.
In any case I use the copper (or oxide, suboxide, or carbonate), so repro-
duced in the decomposition of sulphate of soda, as first above stated.
Thus, the same copper serves for an indefinite number of decompositions.
If impurities accumulate they may be removed by washing the sulphuret

page_text: before roasting, with dilute hydrochloric acid. The sulphuric acid produced
may also be used in the soda manufacture as in the ordinary process. In this
way the same sulphur would serve for repeated decompositions.
I claim as of my Invention,―
First, the fluxing of copper or any of its oxides or carbonates with sulphate
of soda and coal or other carbonaceous material, for the purpose aforesaid, and
in proportion and manner substantially as aforesaid.
Second, the treating this fused mass so as to obtain therefrom carbonate of
soda and a residual sulphuret of copper, substantially as described.
Third, the treating the residual sulphuret so obtained in such a way as to
produce oxide, or suboxide of copper, or metallic copper, and sulphurous and
sulphuric acids, or so as to produce sulphate of copper, substantially as
described.
And, fourth, the treating the sulphate of copper obtained from said
residual sulphuret in such a way as to produce sulphate of soda and copper, or
oxide or carbonate of copper, substantially as herein-before described.